.sqlx/query-0268f0c43abe34a3147f0a43f0e11bf302a3750ecadf28b1d6af62da62934f87.json

@@ -0,0 +1,27 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "UPDATE\n                        cqrs_billing_line_item_query\n                    SET\n                        version = $1,\n                        product_name = $2,\n                        product_id = $3,\n                        line_item_id = $4,\n                        quantity_minor_unit = $5,\n                        quantity_minor_number = $6,\n                        quantity_major_unit = $7,\n                        quantity_major_number = $8,\n                        created_time = $9,\n                        bill_id = $10,\n                        price_per_unit_minor = $11 ,\n                        price_per_unit_major = $12,\n                        price_per_unit_currency = $13,\n                            deleted = $14;",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int8",
+        "Text",
+        "Uuid",
+        "Uuid",
+        "Text",
+        "Int4",
+        "Text",
+        "Int4",
+        "Timestamptz",
+        "Uuid",
+        "Int4",
+        "Int4",
+        "Text",
+        "Bool"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "0268f0c43abe34a3147f0a43f0e11bf302a3750ecadf28b1d6af62da62934f87"
+}

.sqlx/query-03b31d653e96f3b28ff15c86ff5801fe319ba86a15c09aacc4990a7a58849081.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_billing_store_query\n                WHERE\n                    name = $1\n                AND\n                    deleted = false\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Text"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "03b31d653e96f3b28ff15c86ff5801fe319ba86a15c09aacc4990a7a58849081"
+}

.sqlx/query-0bf69e4af7657572bf84633ecf8e2649a7b5baa3fc3abbb6ee7f522fedf3062e.json

@@ -0,0 +1,28 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                store_id, version\n             FROM\n                cqrs_billing_store_query\n            WHERE\n                store_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "store_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 1,
+        "name": "version",
+        "type_info": "Int8"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      false
+    ]
+  },
+  "hash": "0bf69e4af7657572bf84633ecf8e2649a7b5baa3fc3abbb6ee7f522fedf3062e"
+}

.sqlx/query-0d6ba3039f3419dd34a609ae207ac7ca9cf88099aa273972271040852794caa5.json

@@ -0,0 +1,94 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                product_name,\n                product_id,\n                line_item_id,\n                quantity_minor_unit,\n                quantity_minor_number,\n                quantity_major_unit,\n                quantity_major_number,\n                created_time,\n                bill_id,\n                price_per_unit_minor,\n                price_per_unit_major,\n                price_per_unit_currency,\n                deleted\n             FROM\n                cqrs_billing_line_item_query\n            WHERE\n                line_item_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "product_name",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 1,
+        "name": "product_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 2,
+        "name": "line_item_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 3,
+        "name": "quantity_minor_unit",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 4,
+        "name": "quantity_minor_number",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 5,
+        "name": "quantity_major_unit",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 6,
+        "name": "quantity_major_number",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 7,
+        "name": "created_time",
+        "type_info": "Timestamptz"
+      },
+      {
+        "ordinal": 8,
+        "name": "bill_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 9,
+        "name": "price_per_unit_minor",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 10,
+        "name": "price_per_unit_major",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 11,
+        "name": "price_per_unit_currency",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 12,
+        "name": "deleted",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      false
+    ]
+  },
+  "hash": "0d6ba3039f3419dd34a609ae207ac7ca9cf88099aa273972271040852794caa5"
+}

.sqlx/query-0e4316d20c96a7fcfcb68a98865de8e3c0e33e22f2d2cd67fdd671b1f94ab8ea.json

@@ -0,0 +1,15 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "INSERT INTO cqrs_billing_bill_next_token_id\n                        (token_number, store_id)\n                    VALUES\n                        ($1, $2);",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int4",
+        "Uuid"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "0e4316d20c96a7fcfcb68a98865de8e3c0e33e22f2d2cd67fdd671b1f94ab8ea"
+}

.sqlx/query-2af9418499c040df68031e79f7bcbdaa293f1d363f06f5926adfd038783171c4.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_billing_bill_next_token_id\n                WHERE\n                    store_id = $1\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "2af9418499c040df68031e79f7bcbdaa293f1d363f06f5926adfd038783171c4"
+}

.sqlx/query-3811531518316435c32223582f9de6bdfefc19839129577407a1e4071f5c49f6.json

@@ -0,0 +1,19 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "UPDATE\n                        cqrs_billing_store_query\n                    SET\n                        version = $1,\n                        name = $2,\n                        address = $3,\n                        store_id = $4,\n                        owner = $5,\n                        deleted = $6;",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int8",
+        "Text",
+        "Text",
+        "Uuid",
+        "Uuid",
+        "Bool"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "3811531518316435c32223582f9de6bdfefc19839129577407a1e4071f5c49f6"
+}

.sqlx/query-6ac0c3c64749d1eb4a93f8727b56d6a2c9e9b1e49258b38ed1dbebf2f601e99e.json

@@ -0,0 +1,27 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "INSERT INTO cqrs_billing_line_item_query (\n                        version,\n                        product_name,\n                        product_id,\n                        line_item_id,\n                        quantity_minor_unit,\n                        quantity_minor_number,\n                        quantity_major_unit,\n                        quantity_major_number,\n                        created_time,\n                        bill_id,\n                        price_per_unit_minor,\n                        price_per_unit_major,\n                        price_per_unit_currency,\n                        deleted\n                    ) VALUES (\n                        $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14\n                    );",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int8",
+        "Text",
+        "Uuid",
+        "Uuid",
+        "Text",
+        "Int4",
+        "Text",
+        "Int4",
+        "Timestamptz",
+        "Uuid",
+        "Int4",
+        "Int4",
+        "Text",
+        "Bool"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "6ac0c3c64749d1eb4a93f8727b56d6a2c9e9b1e49258b38ed1dbebf2f601e99e"
+}

.sqlx/query-6d9b6f386f4425d45d6aa8f7c2331c44587f54c3583849d07d81e87e1f773c2b.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "INSERT INTO cqrs_billing_bill_query (\n                        version,\n                        created_time,\n                        store_id,\n                        bill_id,\n                        token_number,\n                        total_price_major,\n                        total_price_minor,\n                        total_price_currency,\n                        deleted\n\n                    ) VALUES (\n                        $1, $2, $3, $4, $5, $6, $7, $8, $9\n                    );",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int8",
+        "Timestamptz",
+        "Uuid",
+        "Uuid",
+        "Int4",
+        "Int4",
+        "Int4",
+        "Text",
+        "Bool"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "6d9b6f386f4425d45d6aa8f7c2331c44587f54c3583849d07d81e87e1f773c2b"
+}

.sqlx/query-78008f1b0d3f366937c72a181b19217cd9f28f1ebe73ddc081ec2f7bec5dc1b3.json

@@ -0,0 +1,19 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "INSERT INTO cqrs_billing_store_query (\n                        version, name, address, store_id, owner, deleted\n                    ) VALUES (\n                        $1, $2, $3, $4, $5, $6\n                    );",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int8",
+        "Text",
+        "Text",
+        "Uuid",
+        "Uuid",
+        "Bool"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "78008f1b0d3f366937c72a181b19217cd9f28f1ebe73ddc081ec2f7bec5dc1b3"
+}

.sqlx/query-835a3afa5e16c762d021c4ca889b8c9ce62cf39e4a516511f436cba04520fddd.json

@@ -0,0 +1,28 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                bill_id, version\n             FROM\n                cqrs_billing_bill_query\n            WHERE\n                bill_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "bill_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 1,
+        "name": "version",
+        "type_info": "Int8"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      false
+    ]
+  },
+  "hash": "835a3afa5e16c762d021c4ca889b8c9ce62cf39e4a516511f436cba04520fddd"
+}

.sqlx/query-859920462d8e008b34bfc7467140d382b164f80a255dfe805abcd12cd43e17f3.json

@@ -0,0 +1,14 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "DELETE FROM cqrs_billing_bill_next_token_id WHERE store_id = $1",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "859920462d8e008b34bfc7467140d382b164f80a255dfe805abcd12cd43e17f3"
+}

.sqlx/query-91a8472f079a5221a94cdf5bf1a4da078ac5fe27b022d41948ceb5d554b7f0fa.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_billing_bill_query\n                WHERE\n                    bill_id = $1\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "91a8472f079a5221a94cdf5bf1a4da078ac5fe27b022d41948ceb5d554b7f0fa"
+}

.sqlx/query-a80999e0bed9e7535187b20eb501258adf1c319543da07a8d79de67394b83eeb.json

@@ -0,0 +1,28 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                line_item_id, version\n             FROM\n                cqrs_billing_line_item_query\n            WHERE\n                line_item_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "line_item_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 1,
+        "name": "version",
+        "type_info": "Int8"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      false
+    ]
+  },
+  "hash": "a80999e0bed9e7535187b20eb501258adf1c319543da07a8d79de67394b83eeb"
+}

.sqlx/query-b0c2747901658847d7c765401de06cba772713dfdc11e30e92ad4842cbbb8a62.json

@@ -0,0 +1,64 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                created_time,\n                store_id,\n                bill_id,\n                token_number,\n                total_price_major,\n                total_price_minor,\n                total_price_currency,\n                deleted\n             FROM\n                cqrs_billing_bill_query\n            WHERE\n                bill_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "created_time",
+        "type_info": "Timestamptz"
+      },
+      {
+        "ordinal": 1,
+        "name": "store_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 2,
+        "name": "bill_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 3,
+        "name": "token_number",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 4,
+        "name": "total_price_major",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 5,
+        "name": "total_price_minor",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 6,
+        "name": "total_price_currency",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 7,
+        "name": "deleted",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      false,
+      false,
+      false,
+      true,
+      true,
+      true,
+      false
+    ]
+  },
+  "hash": "b0c2747901658847d7c765401de06cba772713dfdc11e30e92ad4842cbbb8a62"
+}

.sqlx/query-b335fc519289a42c707855b620a35433d3f8bd1e798772c05fc156494c036ef5.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "UPDATE\n                        cqrs_billing_bill_query\n                    SET\n                        version = $1,\n\n                        created_time = $2,\n                        store_id = $3,\n                        bill_id = $4,\n                        token_number = $5,\n                        total_price_major = $6,\n                        total_price_minor = $7,\n                        total_price_currency = $8,\n\n                        deleted = $9;",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int8",
+        "Timestamptz",
+        "Uuid",
+        "Uuid",
+        "Int4",
+        "Int4",
+        "Int4",
+        "Text",
+        "Bool"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "b335fc519289a42c707855b620a35433d3f8bd1e798772c05fc156494c036ef5"
+}

.sqlx/query-ba895b4310f182a73d88df08255dc89374f95ea0e3967124cb1e414c52d0428a.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_billing_store_query\n                WHERE\n                    store_id = $1\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "ba895b4310f182a73d88df08255dc89374f95ea0e3967124cb1e414c52d0428a"
+}

.sqlx/query-c1308bfe8d0d602e154a7d02df7e229e775326bf554e935b688585d0be253934.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_billing_line_item_query\n                WHERE\n                    line_item_id = $1\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "c1308bfe8d0d602e154a7d02df7e229e775326bf554e935b688585d0be253934"
+}

.sqlx/query-c3f26f3816104a510a4630d5d3d27178f9bcf4055cbf176b5e8fb2376a5972ba.json

@@ -0,0 +1,46 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                name, address, store_id, owner, deleted\n             FROM\n                cqrs_billing_store_query\n            WHERE\n                store_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "name",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 1,
+        "name": "address",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 2,
+        "name": "store_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 3,
+        "name": "owner",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 4,
+        "name": "deleted",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false,
+      true,
+      false,
+      false,
+      false
+    ]
+  },
+  "hash": "c3f26f3816104a510a4630d5d3d27178f9bcf4055cbf176b5e8fb2376a5972ba"
+}

.sqlx/query-dbd434995778eab99e753a8fcdce07612061f183c20028ea4995807de6e6fae0.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT\n                token_number\n              FROM\n                cqrs_billing_bill_next_token_id\n             WHERE\n                store_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "token_number",
+        "type_info": "Int4"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      false
+    ]
+  },
+  "hash": "dbd434995778eab99e753a8fcdce07612061f183c20028ea4995807de6e6fae0"
+}

.sqlx/query-df0fde518fdde267e2513fdd2c8d35cbdcf0ae01437b469f1acc93ed11702ce7.json

@@ -0,0 +1,15 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "UPDATE cqrs_billing_bill_next_token_id\n            SET\n                token_number = $1\n            WHERE\n                store_id = $2",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Int4",
+        "Uuid"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "df0fde518fdde267e2513fdd2c8d35cbdcf0ae01437b469f1acc93ed11702ce7"
+}

migrations/20240916121242_cqrs_billing_store_query.sql

@@ -0,0 +1,16 @@
+--- SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+--
+-- SPDX-License-Identifier: AGPL-3.0-or-later
+
+CREATE TABLE IF NOT EXISTS cqrs_billing_store_query
+(
+    version           bigint CHECK (version >= 0) NOT NULL,
+
+	name TEXT NOT NULL,
+	address TEXT,
+	owner UUID NOT NULL,
+	store_id UUID NOT NULL UNIQUE,
+	deleted BOOLEAN NOT NULL DEFAULT FALSE,
+
+    PRIMARY KEY (store_id)
+);

migrations/20240917082053_cqrs_billing_line_item_query.sql

@@ -0,0 +1,29 @@
+-- SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+--
+-- SPDX-License-Identifier: AGPL-3.0-or-later
+
+CREATE TABLE IF NOT EXISTS cqrs_billing_line_item_query
+(
+    version           bigint CHECK (version >= 0) NOT NULL,
+
+    created_time timestamp with time zone DEFAULT (CURRENT_TIMESTAMP) NOT NULL,
+	line_item_id UUID NOT NULL UNIQUE,
+
+	bill_id UUID NOT NULL,
+
+    product_name TEXT NOT NULL,
+	product_id UUID NOT NULL,
+
+    quantity_major_number INTEGER NOT NULL,
+    quantity_minor_number INTEGER NOT NULL,
+    quantity_major_unit TEXT NOT NULL,
+    quantity_minor_unit TEXT NOT NULL,
+
+    price_per_unit_minor INTEGER NOT NULL,
+    price_per_unit_major INTEGER NOT NULL,
+    price_per_unit_currency TEXT NOT NULL,
+
+	deleted BOOLEAN NOT NULL DEFAULT FALSE,
+
+    PRIMARY KEY (line_item_id)
+);

migrations/20240917094208_cqrs_billing_bill_query.sql

@@ -0,0 +1,31 @@
+-- SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+--
+-- SPDX-License-Identifier: AGPL-3.0-or-later
+
+CREATE TABLE IF NOT EXISTS cqrs_billing_bill_query
+(
+    version           bigint CHECK (version >= 0) NOT NULL,
+
+    created_time timestamp with time zone DEFAULT (CURRENT_TIMESTAMP) NOT NULL,
+	bill_id UUID NOT NULL UNIQUE,
+
+
+	store_id UUID NOT NULL,
+	token_number INTEGER NOT NULL,
+
+    total_price_minor INTEGER DEFAULT NULL,
+    total_price_major INTEGER DEFAULT NULL,
+    total_price_currency TEXT DEFAULT NULL,
+
+	deleted BOOLEAN NOT NULL DEFAULT FALSE,
+
+    PRIMARY KEY (bill_id)
+);
+
+CREATE TABLE IF NOT EXISTS cqrs_billing_bill_next_token_id
+(
+	store_id UUID NOT NULL,
+	token_number INTEGER NOT NULL DEFAULT 1,
+
+    PRIMARY KEY (store_id)
+);

src/billing/adapters/output/db/mod.rs

@@ -0,0 +1,4 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+mod postgres;

src/billing/adapters/output/db/postgres/bill_id_exists.rs

@@ -0,0 +1,83 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use uuid::Uuid;
+
+use super::BillingDBPostgresAdapter;
+use crate::billing::application::port::output::db::{bill_id_exists::*, errors::*};
+
+#[async_trait::async_trait]
+impl BillIDExistsDBPort for BillingDBPostgresAdapter {
+    async fn bill_id_exists(&self, bill_id: &Uuid) -> BillingDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_billing_bill_query
+                WHERE
+                    bill_id = $1
+            );",
+            bill_id
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+
+    use super::*;
+    //    use crate::billing::domain::add_product_command::tests::get_customizations;
+    use crate::billing::domain::bill_aggregate::*;
+
+    async fn create_dummy_bill(bill: &Bill, db: &BillingDBPostgresAdapter) {
+        sqlx::query!(
+            "INSERT INTO cqrs_billing_bill_query (
+                    version,
+                    store_id,
+                    bill_id,
+                    token_number,
+                    deleted
+                ) VALUES (
+                    $1, $2, $3, $4, $5
+                );",
+            1,
+            *bill.store_id(),
+            *bill.bill_id(),
+            *bill.token_number() as i32,
+            bill.deleted().clone(),
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+    }
+
+    #[actix_rt::test]
+    async fn test_postgres_product_exists() {
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::BillingDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let bill = Bill::default();
+
+        // state doesn't exist
+        assert!(!db.bill_id_exists(bill.bill_id()).await.unwrap());
+
+        create_dummy_bill(&bill, &db).await;
+
+        // state exists
+        assert!(db.bill_id_exists(bill.bill_id()).await.unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/billing/adapters/output/db/postgres/bill_view.rs

@@ -0,0 +1,371 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::persist::{PersistenceError, ViewContext, ViewRepository};
+use cqrs_es::{EventEnvelope, Query, View};
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use super::errors::*;
+use super::BillingDBPostgresAdapter;
+use crate::billing::domain::bill_aggregate::Bill;
+use crate::billing::domain::events::BillingEvent;
+use crate::utils::parse_aggregate_id::parse_aggregate_id;
+
+pub const NEW_BILL_NON_UUID: &str = "billing_new_bill_non_uuid-asdfa";
+
+// The view for a Bill query, for a standard http application this should
+// be designed to reflect the response dto that will be returned to a user.
+#[derive(Debug, Serialize, Deserialize)]
+pub struct BillView {
+    created_time: OffsetDateTime,
+    store_id: Uuid,
+    bill_id: Uuid,
+
+    token_number: i32,
+
+    total_price_minor: Option<i32>,
+    total_price_major: Option<i32>,
+    total_price_currency: Option<String>,
+
+    deleted: bool,
+}
+
+impl Default for BillView {
+    fn default() -> Self {
+        Self {
+            created_time: OffsetDateTime::now_utc(),
+            store_id: Default::default(),
+            bill_id: Default::default(),
+
+            token_number: Default::default(),
+
+            total_price_minor: Default::default(),
+            total_price_major: Default::default(),
+            total_price_currency: Default::default(),
+
+            deleted: false,
+        }
+    }
+}
+
+// This updates the view with events as they are committed.
+// The logic should be minimal here, e.g., don't calculate the account balance,
+// design the events to carry the balance information instead.
+impl View<Bill> for BillView {
+    fn update(&mut self, event: &EventEnvelope<Bill>) {
+        if let BillingEvent::BillAdded(val) = &event.payload {
+            self.created_time = val.bill().created_time().clone();
+            self.store_id = *val.bill().store_id();
+            self.bill_id = *val.bill().bill_id();
+
+            self.token_number = *val.bill().token_number() as i32;
+
+            self.total_price_minor = val.bill().total_price().as_ref().map(|t| *t.minor() as i32);
+            self.total_price_major = val.bill().total_price().as_ref().map(|t| *t.major() as i32);
+            self.total_price_currency = val
+                .bill()
+                .total_price()
+                .as_ref()
+                .map(|t| t.currency().to_string());
+
+            self.deleted = false;
+        }
+    }
+}
+
+#[async_trait]
+impl ViewRepository<BillView, Bill> for BillingDBPostgresAdapter {
+    async fn load(&self, bill_id: &str) -> Result<Option<BillView>, PersistenceError> {
+        let bill_id = match parse_aggregate_id(bill_id, NEW_BILL_NON_UUID)? {
+            Some((val, _)) => return Ok(Some(val)),
+            None => Uuid::parse_str(bill_id).unwrap(),
+        };
+
+        let res = sqlx::query_as!(
+            BillView,
+            "SELECT 
+                created_time,
+                store_id,
+                bill_id,
+                token_number,
+                total_price_major,
+                total_price_minor,
+                total_price_currency,
+                deleted
+             FROM
+                cqrs_billing_bill_query
+            WHERE
+                bill_id = $1;",
+            bill_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+        Ok(Some(res))
+    }
+
+    async fn load_with_context(
+        &self,
+        bill_id: &str,
+    ) -> Result<Option<(BillView, ViewContext)>, PersistenceError> {
+        let bill_id = match parse_aggregate_id(bill_id, NEW_BILL_NON_UUID)? {
+            Some(val) => return Ok(Some(val)),
+            None => Uuid::parse_str(bill_id).unwrap(),
+        };
+
+        let res = sqlx::query_as!(
+            BillView,
+            "SELECT 
+                created_time,
+                store_id,
+                bill_id,
+                token_number,
+                total_price_major,
+                total_price_minor,
+                total_price_currency,
+                deleted
+             FROM
+                cqrs_billing_bill_query
+            WHERE
+                bill_id = $1;",
+            &bill_id,
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        struct Context {
+            version: i64,
+            bill_id: Uuid,
+        }
+
+        let ctx = sqlx::query_as!(
+            Context,
+            "SELECT 
+                bill_id, version
+             FROM
+                cqrs_billing_bill_query
+            WHERE
+                bill_id = $1;",
+            bill_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        let view_context = ViewContext::new(ctx.bill_id.to_string(), ctx.version);
+        Ok(Some((res, view_context)))
+    }
+
+    async fn update_view(
+        &self,
+        view: BillView,
+        context: ViewContext,
+    ) -> Result<(), PersistenceError> {
+        match context.version {
+            0 => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "INSERT INTO cqrs_billing_bill_query (
+                        version,
+                        created_time,
+                        store_id,
+                        bill_id,
+                        token_number,
+                        total_price_major,
+                        total_price_minor,
+                        total_price_currency,
+                        deleted
+
+                    ) VALUES (
+                        $1, $2, $3, $4, $5, $6, $7, $8, $9
+                    );",
+                    version,
+                    view.created_time,
+                    view.store_id,
+                    view.bill_id,
+                    view.token_number,
+                    view.total_price_major,
+                    view.total_price_minor,
+                    view.total_price_currency,
+                    view.deleted,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+            _ => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "UPDATE
+                        cqrs_billing_bill_query
+                    SET
+                        version = $1,
+
+                        created_time = $2,
+                        store_id = $3,
+                        bill_id = $4,
+                        token_number = $5,
+                        total_price_major = $6,
+                        total_price_minor = $7,
+                        total_price_currency = $8,
+
+                        deleted = $9;",
+                    version,
+                    view.created_time,
+                    view.store_id,
+                    view.bill_id,
+                    view.token_number,
+                    view.total_price_major,
+                    view.total_price_minor,
+                    view.total_price_currency,
+                    view.deleted,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+pub struct SimpleLoggingQuery {}
+
+// Our simplest query, this is great for debugging but absolutely useless in production.
+// This query just pretty prints the events as they are processed.
+#[async_trait]
+impl Query<Bill> for SimpleLoggingQuery {
+    async fn dispatch(&self, aggregate_id: &str, events: &[EventEnvelope<Bill>]) {
+        for event in events {
+            let payload = serde_json::to_string_pretty(&event.payload).unwrap();
+            println!("{}-{}\n{}", aggregate_id, event.sequence, payload);
+        }
+    }
+}
+
+#[async_trait]
+impl Query<Bill> for BillingDBPostgresAdapter {
+    async fn dispatch(&self, bill_id: &str, events: &[EventEnvelope<Bill>]) {
+        let res = self
+            .load_with_context(bill_id)
+            .await
+            .unwrap_or_else(|_| Some((BillView::default(), ViewContext::new(bill_id.into(), 0))));
+        let (mut view, view_context): (BillView, ViewContext) = res.unwrap();
+        for event in events {
+            view.update(event);
+        }
+        self.update_view(view, view_context).await.unwrap();
+    }
+}
+
+// Our second query, this one will be handled with Postgres `GenericQuery`
+// which will serialize and persist our view after it is updated. It also
+// provides a `load` method to deserialize the view on request.
+//pub type BillQuery = GenericQuery<BillingDBPostgresAdapter, BillView, Bill>;
+//pub type BillQuery = Query<dyn BillingDBPostgresAdapter, BillView, Bill>;
+
+//#[cfg(test)]
+//mod tests {
+//    use super::*;
+//
+//    use postgres_es::PostgresCqrs;
+//
+//    use crate::{
+//        db::migrate::*,
+//        billing::{
+//            application::services::{
+//                add_category_service::tests::mock_add_category_service, add_customization_service::tests::mock_add_customization_service, add_line_item_service::tests::mock_add_line_item_service, add_product_service::tests::mock_add_product_service, add_bill_service::AddBillServiceBuilder, update_category_service::tests::mock_update_category_service, update_customization_service::tests::mock_update_customization_service, update_product_service::tests::mock_update_product_service, update_bill_service::tests::mock_update_bill_service, BillingServicesBuilder
+//            },
+//            domain::{
+//                add_category_command::AddCategoryCommand, add_customization_command,
+//                add_product_command::tests::get_command, add_bill_command::AddBillCommand,
+//                commands::BillingCommand,
+//                update_category_command::tests::get_update_category_command,
+//                update_customization_command::tests::get_update_customization_command,
+//                update_product_command, update_bill_command::tests::get_update_bill_cmd,
+//            },
+//        },
+//        tests::bdd::IS_NEVER_CALLED,
+//        utils::{random_string::GenerateRandomStringInterface, uuid::tests::UUID},
+//    };
+//    use std::sync::Arc;
+//
+//    #[actix_rt::test]
+//    async fn pg_query() {
+//        let settings = crate::settings::tests::get_settings().await;
+//        //let settings = crate::settings::Settings::new().unwrap();
+//        settings.create_db().await;
+//
+//        let db = crate::db::sqlx_postgres::Postgres::init(&settings.database.url).await;
+//        db.migrate().await;
+//        let db = BillingDBPostgresAdapter::new(db.pool.clone());
+//
+//        let simple_query = SimpleLoggingQuery {};
+//
+//        let queries: Vec<Box<dyn Query<Bill>>> =
+//            vec![Box::new(simple_query), Box::new(db.clone())];
+//
+//        let services = BillingServicesBuilder::default()
+//            .add_bill(Arc::new(
+//                AddBillServiceBuilder::default()
+//                    .db_bill_id_exists(Arc::new(db.clone()))
+//                    .db_bill_name_exists(Arc::new(db.clone()))
+//                    .get_uuid(Arc::new(crate::utils::uuid::GenerateUUID {}))
+//                    .build()
+//                    .unwrap(),
+//            ))
+//            .add_category(mock_add_category_service(
+//                IS_NEVER_CALLED,
+//                AddCategoryCommand::new("foo".into(), None, UUID, UUID).unwrap(),
+//            ))
+//            .add_product(mock_add_product_service(IS_NEVER_CALLED, get_command()))
+//            .add_customization(mock_add_customization_service(
+//                IS_NEVER_CALLED,
+//                add_customization_command::tests::get_command(),
+//            ))
+//            .update_product(mock_update_product_service(
+//                IS_NEVER_CALLED,
+//                update_product_command::tests::get_command(),
+//            ))
+//            .update_customization(mock_update_customization_service(
+//                IS_NEVER_CALLED,
+//                get_update_customization_command(),
+//            ))
+//            .update_category(mock_update_category_service(
+//                IS_NEVER_CALLED,
+//                get_update_category_command(),
+//            ))
+//            .update_bill(mock_update_bill_service(
+//                IS_NEVER_CALLED,
+//                get_update_bill_cmd(),
+//            ))
+//            .build()
+//            .unwrap();
+//
+//        let (cqrs, _bill_query): (
+//            Arc<PostgresCqrs<Bill>>,
+//            Arc<dyn ViewRepository<BillView, Bill>>,
+//        ) = (
+//            Arc::new(postgres_es::postgres_cqrs(
+//                db.pool.clone(),
+//                queries,
+//                Arc::new(services),
+//            )),
+//            Arc::new(db.clone()),
+//        );
+//
+//        let rand = crate::utils::random_string::GenerateRandomString {};
+//        let cmd = AddBillCommand::new(rand.get_random(10), None, UUID).unwrap();
+//        cqrs.execute("", BillingCommand::AddBill(cmd.clone()))
+//            .await
+//            .unwrap();
+//
+//        settings.drop_db().await;
+//    }
+//}

src/billing/adapters/output/db/postgres/errors.rs

@@ -0,0 +1,79 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::borrow::Cow;
+
+use cqrs_es::persist::PersistenceError;
+use sqlx::Error as SqlxError;
+
+use crate::billing::application::port::output::db::errors::BillingDBError;
+
+impl From<SqlxError> for BillingDBError {
+    fn from(e: SqlxError) -> Self {
+        log::error!("[postgres] err: {}", e);
+        if let SqlxError::Database(err) = e {
+            if err.code() == Some(Cow::from("23505")) {
+                let msg = err.message();
+                if msg.contains("cqrs_inventory_store_query_store_id_key") {
+                    return Self::DuplicateStoreID;
+                } else {
+                    println!("{msg}");
+                }
+            }
+        }
+        Self::InternalError
+    }
+}
+
+/// map custom row not found error to DB error
+pub fn map_row_not_found_err(e: SqlxError, row_not_found: BillingDBError) -> BillingDBError {
+    if let SqlxError::RowNotFound = e {
+        row_not_found
+    } else {
+        e.into()
+    }
+}
+
+#[derive(Debug)]
+pub enum PostgresAggregateError {
+    OptimisticLock,
+    ConnectionError(Box<dyn std::error::Error + Send + Sync + 'static>),
+    DeserializationError(Box<dyn std::error::Error + Send + Sync + 'static>),
+    UnknownError(Box<dyn std::error::Error + Send + Sync + 'static>),
+}
+
+impl From<SqlxError> for PostgresAggregateError {
+    fn from(err: SqlxError) -> Self {
+        // TODO: improve error handling
+        match &err {
+            SqlxError::Database(database_error) => {
+                if let Some(code) = database_error.code() {
+                    if code.as_ref() == "23505" {
+                        return PostgresAggregateError::OptimisticLock;
+                    }
+                }
+                PostgresAggregateError::UnknownError(Box::new(err))
+            }
+            SqlxError::Io(_) | SqlxError::Tls(_) => {
+                PostgresAggregateError::ConnectionError(Box::new(err))
+            }
+            _ => PostgresAggregateError::UnknownError(Box::new(err)),
+        }
+    }
+}
+
+impl From<PostgresAggregateError> for PersistenceError {
+    fn from(err: PostgresAggregateError) -> Self {
+        match err {
+            PostgresAggregateError::OptimisticLock => PersistenceError::OptimisticLockError,
+            PostgresAggregateError::ConnectionError(error) => {
+                PersistenceError::ConnectionError(error)
+            }
+            PostgresAggregateError::DeserializationError(error) => {
+                PersistenceError::UnknownError(error)
+            }
+            PostgresAggregateError::UnknownError(error) => PersistenceError::UnknownError(error),
+        }
+    }
+}

src/billing/adapters/output/db/postgres/line_item_id_exists.rs

@@ -0,0 +1,109 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use uuid::Uuid;
+
+use super::BillingDBPostgresAdapter;
+use crate::billing::application::port::output::db::{errors::*, line_item_id_exists::*};
+
+#[async_trait::async_trait]
+impl LineItemIDExistsDBPort for BillingDBPostgresAdapter {
+    async fn line_item_id_exists(&self, line_item_id: &Uuid) -> BillingDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_billing_line_item_query
+                WHERE
+                    line_item_id = $1
+            );",
+            line_item_id
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+
+    use super::*;
+    //    use crate::billing::domain::add_product_command::tests::get_customizations;
+    use crate::billing::domain::line_item_aggregate::*;
+
+    async fn create_dummy_line_item(line_item: &LineItem, db: &BillingDBPostgresAdapter) {
+        sqlx::query!(
+            "INSERT INTO cqrs_billing_line_item_query (
+                    version,
+                    product_name,
+                    product_id,
+                    line_item_id,
+                    quantity_minor_unit,
+                    quantity_minor_number,
+                    quantity_major_unit,
+                    quantity_major_number,
+
+                    bill_id,
+
+                price_per_unit_minor,
+                price_per_unit_major,
+                price_per_unit_currency,
+
+
+                    deleted
+                ) VALUES (
+                    $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13
+                );",
+            1,
+            line_item.product_name(),
+            line_item.product_id(),
+            line_item.line_item_id(),
+            line_item.quantity().major().unit().to_string(),
+            line_item.quantity().major().number().clone() as i32,
+            line_item.quantity().minor().unit().to_string(),
+            line_item.quantity().minor().number().clone() as i32,
+            line_item.bill_id(),
+            *line_item.price_per_unit().minor() as i32,
+            *line_item.price_per_unit().major() as i32,
+            line_item.price_per_unit().currency().to_string(),
+            line_item.deleted().clone(),
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+    }
+
+    #[actix_rt::test]
+    async fn test_postgres_product_exists() {
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::BillingDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let line_item = LineItem::default();
+
+        // state doesn't exist
+        assert!(!db
+            .line_item_id_exists(line_item.line_item_id())
+            .await
+            .unwrap());
+
+        create_dummy_line_item(&line_item, &db).await;
+
+        // state exists
+        assert!(db
+            .line_item_id_exists(line_item.product_id())
+            .await
+            .unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/billing/adapters/output/db/postgres/line_item_view.rs

@@ -0,0 +1,347 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::str::FromStr;
+
+use async_trait::async_trait;
+use cqrs_es::persist::{PersistenceError, ViewContext, ViewRepository};
+use cqrs_es::{EventEnvelope, Query, View};
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use super::errors::*;
+use super::BillingDBPostgresAdapter;
+use crate::billing::domain::events::BillingEvent;
+use crate::billing::domain::line_item_aggregate::*;
+use crate::types::currency::*;
+use crate::types::quantity::*;
+use crate::utils::parse_aggregate_id::parse_aggregate_id;
+
+pub const NEW_LINE_ITEM_NON_UUID: &str = "new_line_item_non_uuid-asdfa-billing";
+
+// The view for a LineItem query, for a standard http application this should
+// be designed to reflect the response dto that will be returned to a user.
+#[derive(Debug, Serialize, Deserialize)]
+pub struct LineItemView {
+    product_name: String,
+    product_id: Uuid,
+    bill_id: Uuid,
+    created_time: OffsetDateTime,
+
+    line_item_id: Uuid,
+
+    quantity_major_number: i32,
+    quantity_minor_number: i32,
+    quantity_major_unit: String,
+    quantity_minor_unit: String,
+
+    price_per_unit_major: i32,
+    price_per_unit_minor: i32,
+    price_per_unit_currency: String,
+
+    deleted: bool,
+}
+
+impl Default for LineItemView {
+    fn default() -> Self {
+        Self {
+            created_time: OffsetDateTime::now_utc(),
+            product_name: Default::default(),
+            product_id: Default::default(),
+            bill_id: Default::default(),
+
+            line_item_id: Default::default(),
+
+            price_per_unit_minor: Default::default(),
+            price_per_unit_major: Default::default(),
+            price_per_unit_currency: Default::default(),
+
+            quantity_major_number: Default::default(),
+            quantity_minor_number: Default::default(),
+            quantity_major_unit: Default::default(),
+            quantity_minor_unit: Default::default(),
+            deleted: false,
+        }
+    }
+}
+
+impl From<LineItemView> for LineItem {
+    fn from(v: LineItemView) -> Self {
+        let quantity = QuantityBuilder::default()
+            .minor(
+                QuantityPartBuilder::default()
+                    .number(v.quantity_minor_number as usize)
+                    .unit(QuantityUnit::from_str(&v.quantity_minor_unit).unwrap())
+                    .build()
+                    .unwrap(),
+            )
+            .major(
+                QuantityPartBuilder::default()
+                    .number(v.quantity_major_number as usize)
+                    .unit(QuantityUnit::from_str(&v.quantity_major_unit).unwrap())
+                    .build()
+                    .unwrap(),
+            )
+            .build()
+            .unwrap();
+
+        let price_per_unit = PriceBuilder::default()
+            .minor(v.price_per_unit_minor as usize)
+            .major(v.price_per_unit_major as usize)
+            .currency(Currency::from_str(&v.price_per_unit_currency).unwrap())
+            .build()
+            .unwrap();
+
+        LineItemBuilder::default()
+            .product_name(v.product_name)
+            .line_item_id(v.line_item_id)
+            .quantity(quantity)
+            .created_time(v.created_time)
+            .product_id(v.product_id)
+            .price_per_unit(price_per_unit)
+            .bill_id(v.bill_id)
+            .deleted(v.deleted)
+            .build()
+            .unwrap()
+    }
+}
+
+// This updates the view with events as they are committed.
+// The logic should be minimal here, e.g., don't calculate the account balance,
+// design the events to carry the balance information instead.
+impl View<LineItem> for LineItemView {
+    fn update(&mut self, event: &EventEnvelope<LineItem>) {
+        match &event.payload {
+            BillingEvent::LineItemAdded(val) => {
+                self.product_name = val.line_item().product_name().into();
+                self.product_id = *val.line_item().product_id();
+                self.line_item_id = *val.line_item().line_item_id();
+
+                self.quantity_major_number = *val.line_item().quantity().major().number() as i32;
+                self.quantity_minor_number = *val.line_item().quantity().minor().number() as i32;
+                self.quantity_major_unit = val.line_item().quantity().major().unit().to_string();
+                self.quantity_minor_unit = val.line_item().quantity().minor().unit().to_string();
+
+                self.price_per_unit_major = *val.line_item().price_per_unit().major() as i32;
+                self.price_per_unit_minor = *val.line_item().price_per_unit().minor() as i32;
+                self.price_per_unit_currency =
+                    val.line_item().price_per_unit().currency().to_string();
+
+                self.created_time = val.line_item().created_time().clone();
+                self.bill_id = *val.line_item().bill_id();
+
+                self.deleted = false;
+            }
+            _ => (),
+        }
+    }
+}
+
+#[async_trait]
+impl ViewRepository<LineItemView, LineItem> for BillingDBPostgresAdapter {
+    async fn load(&self, line_item_id: &str) -> Result<Option<LineItemView>, PersistenceError> {
+        let line_item_id = match parse_aggregate_id(line_item_id, NEW_LINE_ITEM_NON_UUID)? {
+            Some((val, _)) => return Ok(Some(val)),
+            None => Uuid::parse_str(line_item_id).unwrap(),
+        };
+
+        let res = sqlx::query_as!(
+            LineItemView,
+            "SELECT 
+                product_name,
+                product_id,
+                line_item_id,
+                quantity_minor_unit,
+                quantity_minor_number,
+                quantity_major_unit,
+                quantity_major_number,
+                created_time,
+                bill_id,
+                price_per_unit_minor,
+                price_per_unit_major,
+                price_per_unit_currency,
+                deleted
+             FROM
+                cqrs_billing_line_item_query
+            WHERE
+                line_item_id = $1;",
+            line_item_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        Ok(Some(res))
+    }
+
+    async fn load_with_context(
+        &self,
+        line_item_id: &str,
+    ) -> Result<Option<(LineItemView, ViewContext)>, PersistenceError> {
+        let line_item_id = match parse_aggregate_id(line_item_id, NEW_LINE_ITEM_NON_UUID)? {
+            Some(val) => return Ok(Some(val)),
+            None => Uuid::parse_str(line_item_id).unwrap(),
+        };
+
+        let res = sqlx::query_as!(
+            LineItemView,
+            "SELECT 
+                product_name,
+                product_id,
+                line_item_id,
+                quantity_minor_unit,
+                quantity_minor_number,
+                quantity_major_unit,
+                quantity_major_number,
+                created_time,
+                bill_id,
+                price_per_unit_minor,
+                price_per_unit_major,
+                price_per_unit_currency,
+                deleted
+             FROM
+                cqrs_billing_line_item_query
+            WHERE
+                line_item_id = $1;",
+            line_item_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        struct Context {
+            version: i64,
+            line_item_id: Uuid,
+        }
+
+        let ctx = sqlx::query_as!(
+            Context,
+            "SELECT 
+                line_item_id, version
+             FROM
+                cqrs_billing_line_item_query
+            WHERE
+                line_item_id = $1;",
+            line_item_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        let view_context = ViewContext::new(ctx.line_item_id.to_string(), ctx.version);
+        Ok(Some((res, view_context)))
+    }
+
+    async fn update_view(
+        &self,
+        view: LineItemView,
+        context: ViewContext,
+    ) -> Result<(), PersistenceError> {
+        match context.version {
+            0 => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "INSERT INTO cqrs_billing_line_item_query (
+                        version,
+                        product_name,
+                        product_id,
+                        line_item_id,
+                        quantity_minor_unit,
+                        quantity_minor_number,
+                        quantity_major_unit,
+                        quantity_major_number,
+                        created_time,
+                        bill_id,
+                        price_per_unit_minor,
+                        price_per_unit_major,
+                        price_per_unit_currency,
+                        deleted
+                    ) VALUES (
+                        $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14
+                    );",
+                    version,
+                    view.product_name,
+                    view.product_id,
+                    view.line_item_id,
+                    view.quantity_minor_unit,
+                    view.quantity_minor_number,
+                    view.quantity_major_unit,
+                    view.quantity_major_number,
+                    view.created_time,
+                    view.bill_id,
+                    view.price_per_unit_minor,
+                    view.price_per_unit_major,
+                    view.price_per_unit_currency,
+                    view.deleted,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+
+            _ => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "UPDATE
+                        cqrs_billing_line_item_query
+                    SET
+                        version = $1,
+                        product_name = $2,
+                        product_id = $3,
+                        line_item_id = $4,
+                        quantity_minor_unit = $5,
+                        quantity_minor_number = $6,
+                        quantity_major_unit = $7,
+                        quantity_major_number = $8,
+                        created_time = $9,
+                        bill_id = $10,
+                        price_per_unit_minor = $11 ,
+                        price_per_unit_major = $12,
+                        price_per_unit_currency = $13,
+                            deleted = $14;",
+                    version,
+                    view.product_name,
+                    view.product_id,
+                    view.line_item_id,
+                    view.quantity_minor_unit,
+                    view.quantity_minor_number,
+                    view.quantity_major_unit,
+                    view.quantity_major_number,
+                    view.created_time,
+                    view.bill_id,
+                    view.price_per_unit_minor,
+                    view.price_per_unit_major,
+                    view.price_per_unit_currency,
+                    view.deleted,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+#[async_trait]
+impl Query<LineItem> for BillingDBPostgresAdapter {
+    async fn dispatch(&self, line_item_id: &str, events: &[EventEnvelope<LineItem>]) {
+        let res = self
+            .load_with_context(line_item_id)
+            .await
+            .unwrap_or_else(|_| {
+                Some((
+                    LineItemView::default(),
+                    ViewContext::new(line_item_id.into(), 0),
+                ))
+            });
+        let (mut view, view_context): (LineItemView, ViewContext) = res.unwrap();
+        for event in events {
+            view.update(event);
+        }
+        self.update_view(view, view_context).await.unwrap();
+    }
+}

src/billing/adapters/output/db/postgres/mod.rs

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+use std::sync::Arc;
+
+use sqlx::postgres::PgPool;
+
+use crate::db::{migrate::RunMigrations, sqlx_postgres::Postgres};
+
+mod bill_id_exists;
+mod bill_view;
+mod errors;
+mod line_item_id_exists;
+mod line_item_view;
+mod next_token_id;
+mod store_id_exists;
+mod store_name_exists;
+mod store_view;
+
+#[derive(Clone)]
+pub struct BillingDBPostgresAdapter {
+    pool: PgPool,
+}
+
+impl BillingDBPostgresAdapter {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+
+    pub fn migratable(&self) -> Arc<dyn RunMigrations> {
+        Arc::new(Postgres::new(self.pool.clone()))
+    }
+}

src/billing/adapters/output/db/postgres/next_token_id.rs

@@ -0,0 +1,111 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use uuid::Uuid;
+
+use super::BillingDBPostgresAdapter;
+use crate::billing::application::port::output::db::{errors::*, next_token_id::*};
+
+struct TokenNumber {
+    token_number: i32,
+}
+
+#[async_trait::async_trait]
+impl NextTokenIDDBPort for BillingDBPostgresAdapter {
+    /// delete record for store_id, so that when next_token_id is called, it'll create and set it
+    /// to 1
+    async fn reset(&self, store_id: &Uuid) -> BillingDBResult<()> {
+        sqlx::query!(
+            "DELETE FROM cqrs_billing_bill_next_token_id WHERE store_id = $1",
+            store_id
+        )
+        .execute(&self.pool)
+        .await?;
+        Ok(())
+    }
+
+    /// increment token ID and return pre-increment value
+    async fn next_token_id(&self, store_id: &Uuid) -> BillingDBResult<usize> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_billing_bill_next_token_id
+                WHERE
+                    store_id = $1
+            );",
+            store_id
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(true) = res.exists {
+            let res = sqlx::query_as!(
+                TokenNumber,
+                "SELECT
+                token_number
+              FROM
+                cqrs_billing_bill_next_token_id
+             WHERE
+                store_id = $1;",
+                store_id
+            )
+            .fetch_one(&self.pool)
+            .await?;
+
+            sqlx::query!(
+                "UPDATE cqrs_billing_bill_next_token_id
+            SET
+                token_number = $1
+            WHERE
+                store_id = $2",
+                res.token_number + 1,
+                store_id
+            )
+            .execute(&self.pool)
+            .await?;
+
+            Ok(res.token_number as usize + 1)
+        } else {
+            sqlx::query!(
+                "INSERT INTO cqrs_billing_bill_next_token_id
+                        (token_number, store_id)
+                    VALUES
+                        ($1, $2);",
+                1,
+                store_id
+            )
+            .execute(&self.pool)
+            .await?;
+
+            Ok(1)
+        }
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+
+    use super::*;
+    //    use crate::billing::domain::add_product_command::tests::get_customizations;
+    use crate::{billing::domain::bill_aggregate::*, utils::uuid::tests::UUID};
+
+    #[actix_rt::test]
+    async fn test_postgres_next_token_id() {
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::BillingDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let store_id = UUID;
+
+        assert_eq!(db.next_token_id(&store_id).await.unwrap(), 1);
+        assert_eq!(db.next_token_id(&store_id).await.unwrap(), 2);
+        assert!(db.reset(&store_id).await.is_ok());
+        assert_eq!(db.next_token_id(&store_id).await.unwrap(), 1);
+
+        settings.drop_db().await;
+    }
+}

src/billing/adapters/output/db/postgres/store_id_exists.rs

@@ -0,0 +1,87 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use uuid::Uuid;
+
+use super::BillingDBPostgresAdapter;
+use crate::billing::application::port::output::db::{errors::*, store_id_exists::*};
+use crate::billing::domain::store_aggregate::*;
+
+#[async_trait::async_trait]
+impl StoreIDExistsDBPort for BillingDBPostgresAdapter {
+    async fn store_id_exists(&self, store_id: &Uuid) -> BillingDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_billing_store_query
+                WHERE
+                    store_id = $1
+            );",
+            store_id
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use uuid::Uuid;
+
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    pub async fn create_dummy_store_record(s: &Store, db: &BillingDBPostgresAdapter) {
+        sqlx::query!(
+            "INSERT INTO cqrs_billing_store_query
+                (version, name, address, store_id, owner, deleted)
+            VALUES ($1, $2, $3, $4, $5 ,$6);",
+            1,
+            s.name(),
+            s.address().as_ref().unwrap(),
+            s.store_id(),
+            s.owner(),
+            false
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+    }
+
+    #[actix_rt::test]
+    async fn test_postgres_store_exists() {
+        let store_id = Uuid::new_v4();
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::BillingDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let store = StoreBuilder::default()
+            .name("store_name".into())
+            .owner(UUID)
+            .address(Some("store_address".into()))
+            .store_id(store_id)
+            .build()
+            .unwrap();
+
+        // state doesn't exist
+        assert!(!db.store_id_exists(store.store_id()).await.unwrap());
+
+        create_dummy_store_record(&store, &db).await;
+
+        // state exists
+        assert!(db.store_id_exists(store.store_id()).await.unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/billing/adapters/output/db/postgres/store_name_exists.rs

@@ -0,0 +1,81 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use super::BillingDBPostgresAdapter;
+use crate::billing::application::port::output::db::{errors::*, store_name_exists::*};
+use crate::billing::domain::store_aggregate::*;
+
+#[async_trait::async_trait]
+impl StoreNameExistsDBPort for BillingDBPostgresAdapter {
+    async fn store_name_exists(&self, s: &Store) -> BillingDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_billing_store_query
+                WHERE
+                    name = $1
+                AND
+                    deleted = false
+            );",
+            s.name(),
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use uuid::Uuid;
+
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+    use crate::billing::adapters::output::db::postgres::store_id_exists::tests::create_dummy_store_record;
+
+    #[actix_rt::test]
+    async fn test_postgres_store_exists() {
+        let store_id = Uuid::new_v4();
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::BillingDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let store = StoreBuilder::default()
+            .name("store_name".into())
+            .owner(UUID)
+            .address(Some("store_address".into()))
+            .store_id(store_id)
+            .build()
+            .unwrap();
+
+        // state doesn't exist
+        assert!(!db.store_name_exists(&store).await.unwrap());
+
+        create_dummy_store_record(&store, &db).await;
+
+        // state exists
+        assert!(db.store_name_exists(&store).await.unwrap());
+
+        // Set store.deleted = true; now db.store_name_exists must return false
+        sqlx::query!(
+            "UPDATE cqrs_billing_store_query SET deleted = true WHERE store_id = $1;",
+            store.store_id()
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+        assert!(!db.store_name_exists(&store).await.unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/billing/adapters/output/db/postgres/store_view.rs

@@ -0,0 +1,302 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::persist::{PersistenceError, ViewContext, ViewRepository};
+use cqrs_es::{EventEnvelope, Query, View};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::errors::*;
+use super::BillingDBPostgresAdapter;
+use crate::billing::domain::events::BillingEvent;
+use crate::billing::domain::store_aggregate::Store;
+use crate::utils::parse_aggregate_id::parse_aggregate_id;
+
+pub const NEW_STORE_NON_UUID: &str = "billing_new_store_non_uuid-asdfa";
+
+// The view for a Store query, for a standard http application this should
+// be designed to reflect the response dto that will be returned to a user.
+#[derive(Debug, Default, Serialize, Deserialize)]
+pub struct StoreView {
+    name: String,
+    address: Option<String>,
+    store_id: Uuid,
+    owner: Uuid,
+    deleted: bool,
+}
+
+// This updates the view with events as they are committed.
+// The logic should be minimal here, e.g., don't calculate the account balance,
+// design the events to carry the balance information instead.
+impl View<Store> for StoreView {
+    fn update(&mut self, event: &EventEnvelope<Store>) {
+        if let BillingEvent::StoreAdded(val) = &event.payload {
+            self.name = val.name().into();
+            self.address = val.address().clone();
+            self.store_id = *val.store_id();
+            self.owner = *val.owner();
+            self.deleted = false;
+        }
+    }
+}
+
+#[async_trait]
+impl ViewRepository<StoreView, Store> for BillingDBPostgresAdapter {
+    async fn load(&self, store_id: &str) -> Result<Option<StoreView>, PersistenceError> {
+        let store_id = match parse_aggregate_id(store_id, NEW_STORE_NON_UUID)? {
+            Some((val, _)) => return Ok(Some(val)),
+            None => Uuid::parse_str(store_id).unwrap(),
+        };
+
+        let res = sqlx::query_as!(
+            StoreView,
+            "SELECT 
+                name, address, store_id, owner, deleted
+             FROM
+                cqrs_billing_store_query
+            WHERE
+                store_id = $1;",
+            store_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+        Ok(Some(res))
+    }
+
+    async fn load_with_context(
+        &self,
+        store_id: &str,
+    ) -> Result<Option<(StoreView, ViewContext)>, PersistenceError> {
+        let store_id = match parse_aggregate_id(store_id, NEW_STORE_NON_UUID)? {
+            Some(val) => return Ok(Some(val)),
+            None => Uuid::parse_str(store_id).unwrap(),
+        };
+
+        let res = sqlx::query_as!(
+            StoreView,
+            "SELECT 
+                name, address, store_id, owner, deleted
+             FROM
+                cqrs_billing_store_query
+            WHERE
+                store_id = $1;",
+            &store_id,
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        struct Context {
+            version: i64,
+            store_id: Uuid,
+        }
+
+        let ctx = sqlx::query_as!(
+            Context,
+            "SELECT 
+                store_id, version
+             FROM
+                cqrs_billing_store_query
+            WHERE
+                store_id = $1;",
+            store_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        let view_context = ViewContext::new(ctx.store_id.to_string(), ctx.version);
+        Ok(Some((res, view_context)))
+    }
+
+    async fn update_view(
+        &self,
+        view: StoreView,
+        context: ViewContext,
+    ) -> Result<(), PersistenceError> {
+        match context.version {
+            0 => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "INSERT INTO cqrs_billing_store_query (
+                        version, name, address, store_id, owner, deleted
+                    ) VALUES (
+                        $1, $2, $3, $4, $5, $6
+                    );",
+                    version,
+                    view.name,
+                    view.address,
+                    view.store_id,
+                    view.owner,
+                    view.deleted,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+            _ => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "UPDATE
+                        cqrs_billing_store_query
+                    SET
+                        version = $1,
+                        name = $2,
+                        address = $3,
+                        store_id = $4,
+                        owner = $5,
+                        deleted = $6;",
+                    version,
+                    view.name,
+                    view.address,
+                    view.store_id,
+                    view.owner,
+                    view.deleted,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+pub struct SimpleLoggingQuery {}
+
+// Our simplest query, this is great for debugging but absolutely useless in production.
+// This query just pretty prints the events as they are processed.
+#[async_trait]
+impl Query<Store> for SimpleLoggingQuery {
+    async fn dispatch(&self, aggregate_id: &str, events: &[EventEnvelope<Store>]) {
+        for event in events {
+            let payload = serde_json::to_string_pretty(&event.payload).unwrap();
+            println!("{}-{}\n{}", aggregate_id, event.sequence, payload);
+        }
+    }
+}
+
+#[async_trait]
+impl Query<Store> for BillingDBPostgresAdapter {
+    async fn dispatch(&self, store_id: &str, events: &[EventEnvelope<Store>]) {
+        let res = self
+            .load_with_context(store_id)
+            .await
+            .unwrap_or_else(|_| Some((StoreView::default(), ViewContext::new(store_id.into(), 0))));
+        let (mut view, view_context): (StoreView, ViewContext) = res.unwrap();
+        for event in events {
+            view.update(event);
+        }
+        self.update_view(view, view_context).await.unwrap();
+    }
+}
+
+// Our second query, this one will be handled with Postgres `GenericQuery`
+// which will serialize and persist our view after it is updated. It also
+// provides a `load` method to deserialize the view on request.
+//pub type StoreQuery = GenericQuery<BillingDBPostgresAdapter, StoreView, Store>;
+//pub type StoreQuery = Query<dyn BillingDBPostgresAdapter, StoreView, Store>;
+
+//#[cfg(test)]
+//mod tests {
+//    use super::*;
+//
+//    use postgres_es::PostgresCqrs;
+//
+//    use crate::{
+//        db::migrate::*,
+//        billing::{
+//            application::services::{
+//                add_category_service::tests::mock_add_category_service, add_customization_service::tests::mock_add_customization_service, add_line_item_service::tests::mock_add_line_item_service, add_product_service::tests::mock_add_product_service, add_store_service::AddStoreServiceBuilder, update_category_service::tests::mock_update_category_service, update_customization_service::tests::mock_update_customization_service, update_product_service::tests::mock_update_product_service, update_store_service::tests::mock_update_store_service, BillingServicesBuilder
+//            },
+//            domain::{
+//                add_category_command::AddCategoryCommand, add_customization_command,
+//                add_product_command::tests::get_command, add_store_command::AddStoreCommand,
+//                commands::BillingCommand,
+//                update_category_command::tests::get_update_category_command,
+//                update_customization_command::tests::get_update_customization_command,
+//                update_product_command, update_store_command::tests::get_update_store_cmd,
+//            },
+//        },
+//        tests::bdd::IS_NEVER_CALLED,
+//        utils::{random_string::GenerateRandomStringInterface, uuid::tests::UUID},
+//    };
+//    use std::sync::Arc;
+//
+//    #[actix_rt::test]
+//    async fn pg_query() {
+//        let settings = crate::settings::tests::get_settings().await;
+//        //let settings = crate::settings::Settings::new().unwrap();
+//        settings.create_db().await;
+//
+//        let db = crate::db::sqlx_postgres::Postgres::init(&settings.database.url).await;
+//        db.migrate().await;
+//        let db = BillingDBPostgresAdapter::new(db.pool.clone());
+//
+//        let simple_query = SimpleLoggingQuery {};
+//
+//        let queries: Vec<Box<dyn Query<Store>>> =
+//            vec![Box::new(simple_query), Box::new(db.clone())];
+//
+//        let services = BillingServicesBuilder::default()
+//            .add_store(Arc::new(
+//                AddStoreServiceBuilder::default()
+//                    .db_store_id_exists(Arc::new(db.clone()))
+//                    .db_store_name_exists(Arc::new(db.clone()))
+//                    .get_uuid(Arc::new(crate::utils::uuid::GenerateUUID {}))
+//                    .build()
+//                    .unwrap(),
+//            ))
+//            .add_category(mock_add_category_service(
+//                IS_NEVER_CALLED,
+//                AddCategoryCommand::new("foo".into(), None, UUID, UUID).unwrap(),
+//            ))
+//            .add_product(mock_add_product_service(IS_NEVER_CALLED, get_command()))
+//            .add_customization(mock_add_customization_service(
+//                IS_NEVER_CALLED,
+//                add_customization_command::tests::get_command(),
+//            ))
+//            .update_product(mock_update_product_service(
+//                IS_NEVER_CALLED,
+//                update_product_command::tests::get_command(),
+//            ))
+//            .update_customization(mock_update_customization_service(
+//                IS_NEVER_CALLED,
+//                get_update_customization_command(),
+//            ))
+//            .update_category(mock_update_category_service(
+//                IS_NEVER_CALLED,
+//                get_update_category_command(),
+//            ))
+//            .update_store(mock_update_store_service(
+//                IS_NEVER_CALLED,
+//                get_update_store_cmd(),
+//            ))
+//            .build()
+//            .unwrap();
+//
+//        let (cqrs, _store_query): (
+//            Arc<PostgresCqrs<Store>>,
+//            Arc<dyn ViewRepository<StoreView, Store>>,
+//        ) = (
+//            Arc::new(postgres_es::postgres_cqrs(
+//                db.pool.clone(),
+//                queries,
+//                Arc::new(services),
+//            )),
+//            Arc::new(db.clone()),
+//        );
+//
+//        let rand = crate::utils::random_string::GenerateRandomString {};
+//        let cmd = AddStoreCommand::new(rand.get_random(10), None, UUID).unwrap();
+//        cqrs.execute("", BillingCommand::AddStore(cmd.clone()))
+//            .await
+//            .unwrap();
+//
+//        settings.drop_db().await;
+//    }
+//}

src/billing/adapters/output/mod.rs

@@ -1,3 +1,4 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+mod db;

src/billing/application/mod.rs

@@ -2,5 +2,5 @@
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
-mod port;
-mod services;
+pub mod port;
+pub mod services;

src/billing/application/port/mod.rs

@@ -2,5 +2,5 @@
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
-mod input;
-mod output;
+pub mod input;
+pub mod output;

src/billing/application/port/output/db/bill_id_exists.rs

@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+use uuid::Uuid;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait BillIDExistsDBPort: Send + Sync {
+    async fn bill_id_exists(&self, c: &Uuid) -> BillingDBResult<bool>;
+}
+
+pub type BillIDExistsDBPortObj = std::sync::Arc<dyn BillIDExistsDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_bill_id_exists_db_port_false(times: Option<usize>) -> BillIDExistsDBPortObj {
+        let mut m = MockBillIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_bill_id_exists()
+                .times(times)
+                .returning(|_| Ok(false));
+        } else {
+            m.expect_bill_id_exists().returning(|_| Ok(false));
+        }
+
+        Arc::new(m)
+    }
+
+    pub fn mock_bill_id_exists_db_port_true(times: Option<usize>) -> BillIDExistsDBPortObj {
+        let mut m = MockBillIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_bill_id_exists()
+                .times(times)
+                .returning(|_| Ok(true));
+        } else {
+            m.expect_bill_id_exists().returning(|_| Ok(true));
+        }
+
+        Arc::new(m)
+    }
+}

src/billing/application/port/output/db/errors.rs

@@ -0,0 +1,19 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_more::Display;
+use serde::{Deserialize, Serialize};
+
+pub type BillingDBResult<V> = Result<V, BillingDBError>;
+
+#[derive(Debug, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum BillingDBError {
+    DuplicateBillID,
+    DuplicateStoreName,
+    DuplicateStoreID,
+    StoreIDNotFound,
+    DuplicateLineItemID,
+    LineItemIDNotFound,
+    InternalError,
+}

src/billing/application/port/output/db/line_item_id_exists.rs

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+use uuid::Uuid;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait LineItemIDExistsDBPort: Send + Sync {
+    async fn line_item_id_exists(&self, line_item_id: &Uuid) -> BillingDBResult<bool>;
+}
+
+pub type LineItemIDExistsDBPortObj = std::sync::Arc<dyn LineItemIDExistsDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_line_item_id_exists_db_port_false(
+        times: Option<usize>,
+    ) -> LineItemIDExistsDBPortObj {
+        let mut m = MockLineItemIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_line_item_id_exists()
+                .times(times)
+                .returning(|_| Ok(false));
+        } else {
+            m.expect_line_item_id_exists().returning(|_| Ok(false));
+        }
+
+        Arc::new(m)
+    }
+
+    pub fn mock_line_item_id_exists_db_port_true(
+        times: Option<usize>,
+    ) -> LineItemIDExistsDBPortObj {
+        let mut m = MockLineItemIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_line_item_id_exists()
+                .times(times)
+                .returning(|_| Ok(true));
+        } else {
+            m.expect_line_item_id_exists().returning(|_| Ok(true));
+        }
+
+        Arc::new(m)
+    }
+}

src/billing/application/port/output/db/mod.rs

@@ -0,0 +1,9 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+pub mod bill_id_exists;
+pub mod errors;
+pub mod line_item_id_exists;
+pub mod next_token_id;
+pub mod store_id_exists;
+pub mod store_name_exists;

src/billing/application/port/output/db/next_token_id.rs

@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+use uuid::Uuid;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait NextTokenIDDBPort: Send + Sync {
+    /// delete record for store_id, so that when next_token_id is called, it'll create and set it
+    /// to 1
+    async fn reset(&self, store_id: &Uuid) -> BillingDBResult<()>;
+
+    /// increment token ID and return pre-increment value
+    async fn next_token_id(&self, store_id: &Uuid) -> BillingDBResult<usize>;
+}
+
+pub type NextTokenIDDBPortObj = std::sync::Arc<dyn NextTokenIDDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_next_token_id_db_port(times: Option<usize>) -> NextTokenIDDBPortObj {
+        let mut m = MockNextTokenIDDBPort::new();
+        if let Some(times) = times {
+            m.expect_next_token_id().times(times).returning(|_| Ok(1));
+        } else {
+            m.expect_next_token_id().returning(|_| Ok(1));
+        }
+
+        Arc::new(m)
+    }
+}

src/billing/application/port/output/db/store_id_exists.rs

@@ -0,0 +1,55 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+use uuid::Uuid;
+
+use crate::billing::domain::store_aggregate::Store;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait StoreIDExistsDBPort: Send + Sync {
+    async fn store_id_exists(&self, store_id: &Uuid) -> BillingDBResult<bool>;
+}
+
+pub type StoreIDExistsDBPortObj = std::sync::Arc<dyn StoreIDExistsDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_store_id_exists_db_port_false(times: Option<usize>) -> StoreIDExistsDBPortObj {
+        let mut m = MockStoreIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_store_id_exists()
+                .times(times)
+                .returning(|_| Ok(false));
+        } else {
+            m.expect_store_id_exists().returning(|_| Ok(false));
+        }
+
+        Arc::new(m)
+    }
+
+    pub fn mock_store_id_exists_db_port_true(times: Option<usize>) -> StoreIDExistsDBPortObj {
+        let mut m = MockStoreIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_store_id_exists()
+                .times(times)
+                .returning(|_| Ok(true));
+        } else {
+            m.expect_store_id_exists().returning(|_| Ok(true));
+        }
+
+        Arc::new(m)
+    }
+}

src/billing/application/port/output/db/store_name_exists.rs

@@ -0,0 +1,54 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+
+use crate::billing::domain::store_aggregate::Store;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait StoreNameExistsDBPort: Send + Sync {
+    async fn store_name_exists(&self, s: &Store) -> BillingDBResult<bool>;
+}
+
+pub type StoreNameExistsDBPortObj = std::sync::Arc<dyn StoreNameExistsDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_store_name_exists_db_port_false(times: Option<usize>) -> StoreNameExistsDBPortObj {
+        let mut m = MockStoreNameExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_store_name_exists()
+                .times(times)
+                .returning(|_| Ok(false));
+        } else {
+            m.expect_store_name_exists().returning(|_| Ok(false));
+        }
+
+        Arc::new(m)
+    }
+
+    pub fn mock_store_name_exists_db_port_true(times: Option<usize>) -> StoreNameExistsDBPortObj {
+        let mut m = MockStoreNameExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_store_name_exists()
+                .times(times)
+                .returning(|_| Ok(true));
+        } else {
+            m.expect_store_name_exists().returning(|_| Ok(true));
+        }
+
+        Arc::new(m)
+    }
+}

src/billing/application/port/output/mod.rs

@@ -1,3 +1,4 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+pub mod db;

src/billing/application/services/add_bill_service.rs

@@ -0,0 +1,125 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::{bill_id_exists::*, next_token_id::*},
+    domain::{
+        add_bill_command::AddBillCommand,
+        bill_added_event::{BillAddedEvent, BillAddedEventBuilder},
+        bill_aggregate::*,
+    },
+};
+use crate::utils::uuid::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait AddBillUseCase: Send + Sync {
+    async fn add_bill(&self, cmd: AddBillCommand) -> BillingResult<BillAddedEvent>;
+}
+
+pub type AddBillServiceObj = Arc<dyn AddBillUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct AddBillService {
+    db_bill_id_exists: BillIDExistsDBPortObj,
+    db_next_token_id: NextTokenIDDBPortObj,
+    get_uuid: GetUUIDInterfaceObj,
+}
+
+#[async_trait::async_trait]
+impl AddBillUseCase for AddBillService {
+    async fn add_bill(&self, cmd: AddBillCommand) -> BillingResult<BillAddedEvent> {
+        let mut bill_id = self.get_uuid.get_uuid();
+
+        loop {
+            if self.db_bill_id_exists.bill_id_exists(&bill_id).await? {
+                bill_id = self.get_uuid.get_uuid();
+                continue;
+            } else {
+                break;
+            }
+        }
+
+        let token_number = self.db_next_token_id.next_token_id(cmd.store_id()).await?;
+
+        let bill = BillBuilder::default()
+            .bill_id(bill_id)
+            .token_number(token_number)
+            .created_time(cmd.created_time().clone())
+            .store_id(*cmd.store_id())
+            .total_price(None)
+            .deleted(false)
+            .build()
+            .unwrap();
+
+        Ok(BillAddedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .bill(bill)
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    //    use crate::billing::domain::add_bill_command::tests::get_command;
+    use crate::utils::uuid::tests::UUID;
+    use crate::{tests::bdd::*, utils::uuid::tests::mock_get_uuid};
+
+    pub fn mock_add_bill_service(times: Option<usize>, cmd: AddBillCommand) -> AddBillServiceObj {
+        let mut m = MockAddBillUseCase::new();
+
+        let bill = BillBuilder::default()
+            .bill_id(UUID)
+            .token_number(1)
+            .total_price(None)
+            .created_time(cmd.created_time().clone())
+            .store_id(*cmd.store_id())
+            .deleted(false)
+            .build()
+            .unwrap();
+
+        let res = BillAddedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .bill(bill)
+            .build()
+            .unwrap();
+
+        if let Some(times) = times {
+            m.expect_add_bill()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_add_bill().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service_bill_doesnt_exist() {
+        let cmd = AddBillCommand::get_cmd();
+
+        let s = AddBillServiceBuilder::default()
+            .db_bill_id_exists(mock_bill_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .db_next_token_id(mock_next_token_id_db_port(IS_CALLED_ONLY_ONCE))
+            .get_uuid(mock_get_uuid(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.add_bill(cmd.clone()).await.unwrap();
+        assert_eq!(res.bill().created_time(), cmd.created_time());
+        assert_eq!(res.bill().store_id(), cmd.store_id());
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+}

src/billing/application/services/add_line_item_service.rs

@@ -0,0 +1,141 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+use time::OffsetDateTime;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::bill_id_exists::*,
+    application::port::output::db::line_item_id_exists::*,
+    domain::{add_line_item_command::*, line_item_added_event::*, line_item_aggregate::*},
+};
+use crate::utils::uuid::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait AddLineItemUseCase: Send + Sync {
+    async fn add_line_item(&self, cmd: AddLineItemCommand) -> BillingResult<LineItemAddedEvent>;
+}
+
+pub type AddLineItemServiceObj = Arc<dyn AddLineItemUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct AddLineItemService {
+    db_line_item_id_exists: LineItemIDExistsDBPortObj,
+    db_bill_id_exists: BillIDExistsDBPortObj,
+    get_uuid: GetUUIDInterfaceObj,
+}
+
+#[async_trait::async_trait]
+impl AddLineItemUseCase for AddLineItemService {
+    async fn add_line_item(&self, cmd: AddLineItemCommand) -> BillingResult<LineItemAddedEvent> {
+        if !self.db_bill_id_exists.bill_id_exists(cmd.bill_id()).await? {
+            return Err(BillingError::BillIDNotFound);
+        }
+
+        let mut line_item_id = self.get_uuid.get_uuid();
+
+        loop {
+            if self
+                .db_line_item_id_exists
+                .line_item_id_exists(&line_item_id)
+                .await?
+            {
+                line_item_id = self.get_uuid.get_uuid();
+                continue;
+            } else {
+                break;
+            }
+        }
+
+        let line_item = LineItemBuilder::default()
+            .created_time(cmd.created_time().clone())
+            .product_name(cmd.product_name().into())
+            .product_id(*cmd.product_id())
+            .bill_id(*cmd.bill_id())
+            .line_item_id(line_item_id)
+            .quantity(cmd.quantity().clone())
+            .price_per_unit(cmd.price_per_unit().clone())
+            .deleted(false)
+            .build()
+            .unwrap();
+
+        Ok(LineItemAddedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .line_item(line_item)
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::billing::domain::line_item_added_event::tests::get_added_line_item_event_from_command;
+    use crate::utils::uuid::tests::UUID;
+    use crate::{tests::bdd::*, utils::uuid::tests::mock_get_uuid};
+
+    pub fn mock_add_line_item_service(
+        times: Option<usize>,
+        cmd: AddLineItemCommand,
+    ) -> AddLineItemServiceObj {
+        let mut m = MockAddLineItemUseCase::new();
+
+        let res = get_added_line_item_event_from_command(&cmd);
+        if let Some(times) = times {
+            m.expect_add_line_item()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_add_line_item().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service() {
+        let cmd = AddLineItemCommand::get_cmd();
+
+        let s = AddLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .db_bill_id_exists(mock_bill_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .get_uuid(mock_get_uuid(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.add_line_item(cmd.clone()).await.unwrap();
+        assert_eq!(res.line_item().product_name(), cmd.product_name());
+        assert_eq!(res.line_item().product_id(), cmd.product_id());
+        assert_eq!(res.line_item().bill_id(), cmd.bill_id());
+        assert_eq!(res.line_item().quantity(), cmd.quantity());
+        assert_eq!(res.line_item().quantity(), cmd.quantity());
+        assert_eq!(res.line_item().created_time(), cmd.created_time());
+        assert!(!res.line_item().deleted());
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+
+    #[actix_rt::test]
+    async fn test_service_bill_id_doesnt_exist() {
+        let cmd = AddLineItemCommand::get_cmd();
+
+        let s = AddLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_false(IS_NEVER_CALLED))
+            .db_bill_id_exists(mock_bill_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .get_uuid(mock_get_uuid(IS_NEVER_CALLED))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.add_line_item(cmd.clone()).await,
+            Err(BillingError::BillIDNotFound)
+        );
+    }
+}

src/billing/application/services/add_store_service.rs

@@ -0,0 +1,149 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::{store_id_exists::*, store_name_exists::*},
+    domain::{
+        add_store_command::AddStoreCommand,
+        store_added_event::{StoreAddedEvent, StoreAddedEventBuilder},
+        store_aggregate::*,
+    },
+};
+use crate::utils::uuid::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait AddStoreUseCase: Send + Sync {
+    async fn add_store(&self, cmd: AddStoreCommand) -> BillingResult<StoreAddedEvent>;
+}
+
+pub type AddStoreServiceObj = Arc<dyn AddStoreUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct AddStoreService {
+    db_store_id_exists: StoreIDExistsDBPortObj,
+    db_store_name_exists: StoreNameExistsDBPortObj,
+    get_uuid: GetUUIDInterfaceObj,
+}
+
+#[async_trait::async_trait]
+impl AddStoreUseCase for AddStoreService {
+    async fn add_store(&self, cmd: AddStoreCommand) -> BillingResult<StoreAddedEvent> {
+        let mut store_id = self.get_uuid.get_uuid();
+
+        loop {
+            if self.db_store_id_exists.store_id_exists(&store_id).await? {
+                store_id = self.get_uuid.get_uuid();
+                continue;
+            } else {
+                break;
+            }
+        }
+
+        let store = StoreBuilder::default()
+            .name(cmd.name().into())
+            .address(cmd.address().as_ref().map(|s| s.to_string()))
+            .owner(*cmd.owner())
+            .store_id(store_id)
+            .build()
+            .unwrap();
+
+        if self.db_store_name_exists.store_name_exists(&store).await? {
+            return Err(BillingError::DuplicateStoreName);
+        }
+
+        Ok(StoreAddedEventBuilder::default()
+            .name(store.name().into())
+            .address(store.address().as_ref().map(|s| s.to_string()))
+            .owner(*cmd.owner())
+            .store_id(store_id)
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::tests::bdd::*;
+    use crate::utils::uuid::tests::*;
+
+    pub fn mock_add_store_service(
+        times: Option<usize>,
+        cmd: AddStoreCommand,
+    ) -> AddStoreServiceObj {
+        let mut m = MockAddStoreUseCase::new();
+
+        let res = StoreAddedEventBuilder::default()
+            .name(cmd.name().into())
+            .address(cmd.address().as_ref().map(|s| s.to_string()))
+            .owner(*cmd.owner())
+            .store_id(UUID)
+            .build()
+            .unwrap();
+
+        if let Some(times) = times {
+            m.expect_add_store()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_add_store().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service_store_id_doesnt_exist() {
+        let name = "foo";
+        let address = "bar";
+        let owner = UUID;
+
+        // address = None
+        let cmd = AddStoreCommand::new(name.into(), Some(address.into()), owner).unwrap();
+
+        let s = AddStoreServiceBuilder::default()
+            .db_store_id_exists(mock_store_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .db_store_name_exists(mock_store_name_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .get_uuid(mock_get_uuid(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.add_store(cmd.clone()).await.unwrap();
+        assert_eq!(res.name(), cmd.name());
+        assert_eq!(res.address(), cmd.address());
+        assert_eq!(res.owner(), cmd.owner());
+        assert_eq!(res.store_id(), &UUID);
+    }
+
+    #[actix_rt::test]
+    async fn test_service_store_name_exists() {
+        let name = "foo";
+        let address = "bar";
+        let owner = UUID;
+
+        // address = None
+        let cmd = AddStoreCommand::new(name.into(), Some(address.into()), owner).unwrap();
+
+        let s = AddStoreServiceBuilder::default()
+            .db_store_id_exists(mock_store_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .db_store_name_exists(mock_store_name_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .get_uuid(mock_get_uuid(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.add_store(cmd.clone()).await,
+            Err(BillingError::DuplicateStoreName)
+        );
+    }
+}

src/billing/application/services/delete_bill_service.rs

@@ -0,0 +1,103 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::bill_id_exists::*,
+    domain::{bill_deleted_event::*, delete_bill_command::DeleteBillCommand},
+};
+
+#[automock]
+#[async_trait::async_trait]
+pub trait DeleteBillUseCase: Send + Sync {
+    async fn delete_bill(&self, cmd: DeleteBillCommand) -> BillingResult<BillDeletedEvent>;
+}
+
+pub type DeleteBillServiceObj = Arc<dyn DeleteBillUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct DeleteBillService {
+    db_bill_id_exists: BillIDExistsDBPortObj,
+}
+
+#[async_trait::async_trait]
+impl DeleteBillUseCase for DeleteBillService {
+    async fn delete_bill(&self, cmd: DeleteBillCommand) -> BillingResult<BillDeletedEvent> {
+        if !self
+            .db_bill_id_exists
+            .bill_id_exists(cmd.bill().bill_id())
+            .await?
+        {
+            return Err(BillingError::BillIDNotFound);
+        }
+
+        Ok(BillDeletedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .bill(cmd.bill().clone())
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::billing::domain::bill_deleted_event::tests::get_deleted_bill_event_from_command;
+    use crate::tests::bdd::*;
+
+    pub fn mock_delete_bill_service(
+        times: Option<usize>,
+        cmd: DeleteBillCommand,
+    ) -> DeleteBillServiceObj {
+        let mut m = MockDeleteBillUseCase::new();
+
+        let res = get_deleted_bill_event_from_command(&cmd);
+
+        if let Some(times) = times {
+            m.expect_delete_bill()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_delete_bill().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service() {
+        let cmd = DeleteBillCommand::get_cmd();
+
+        let s = DeleteBillServiceBuilder::default()
+            .db_bill_id_exists(mock_bill_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.delete_bill(cmd.clone()).await.unwrap();
+        assert_eq!(res.bill(), cmd.bill());
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+
+    #[actix_rt::test]
+    async fn test_service_bill_id_doesnt_exist() {
+        let cmd = DeleteBillCommand::get_cmd();
+
+        let s = DeleteBillServiceBuilder::default()
+            .db_bill_id_exists(mock_bill_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.delete_bill(cmd.clone()).await,
+            Err(BillingError::BillIDNotFound)
+        );
+    }
+}

src/billing/application/services/delete_line_item_service.rs

@@ -0,0 +1,135 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+use time::OffsetDateTime;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::line_item_id_exists::*,
+    domain::{delete_line_item_command::*, line_item_aggregate::*, line_item_deleted_event::*},
+};
+use crate::utils::uuid::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait DeleteLineItemUseCase: Send + Sync {
+    async fn delete_line_item(
+        &self,
+        cmd: DeleteLineItemCommand,
+    ) -> BillingResult<LineItemDeletedEvent>;
+}
+
+pub type DeleteLineItemServiceObj = Arc<dyn DeleteLineItemUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct DeleteLineItemService {
+    db_line_item_id_exists: LineItemIDExistsDBPortObj,
+}
+
+#[async_trait::async_trait]
+impl DeleteLineItemUseCase for DeleteLineItemService {
+    async fn delete_line_item(
+        &self,
+        cmd: DeleteLineItemCommand,
+    ) -> BillingResult<LineItemDeletedEvent> {
+        if !self
+            .db_line_item_id_exists
+            .line_item_id_exists(cmd.line_item().line_item_id())
+            .await?
+        {
+            return Err(BillingError::LineItemIDNotFound);
+        }
+
+        let deleted_line_item = LineItemBuilder::default()
+            .created_time(cmd.line_item().created_time().clone())
+            .product_name(cmd.line_item().product_name().into())
+            .product_id(*cmd.line_item().product_id())
+            .line_item_id(*cmd.line_item().line_item_id())
+            .bill_id(*cmd.line_item().bill_id())
+            .quantity(cmd.line_item().quantity().clone())
+            .price_per_unit(cmd.line_item().price_per_unit().clone())
+            .deleted(true)
+            .build()
+            .unwrap();
+
+        Ok(LineItemDeletedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .line_item(deleted_line_item)
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::billing::domain::line_item_deleted_event::tests::get_deleted_line_item_event_from_command;
+    use crate::tests::bdd::*;
+
+    pub fn mock_delete_line_item_service(
+        times: Option<usize>,
+        cmd: DeleteLineItemCommand,
+    ) -> DeleteLineItemServiceObj {
+        let mut m = MockDeleteLineItemUseCase::new();
+
+        let res = get_deleted_line_item_event_from_command(&cmd);
+        if let Some(times) = times {
+            m.expect_delete_line_item()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_delete_line_item()
+                .returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service() {
+        let cmd = DeleteLineItemCommand::get_cmd();
+
+        let s = DeleteLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.delete_line_item(cmd.clone()).await.unwrap();
+        assert_eq!(
+            res.line_item().product_name(),
+            cmd.line_item().product_name()
+        );
+        assert_eq!(res.line_item().product_id(), cmd.line_item().product_id());
+        assert_eq!(res.line_item().quantity(), cmd.line_item().quantity());
+        assert_eq!(
+            res.line_item().line_item_id(),
+            cmd.line_item().line_item_id()
+        );
+        assert_eq!(res.line_item().bill_id(), cmd.line_item().bill_id());
+        assert!(res.line_item().deleted());
+
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+
+    #[actix_rt::test]
+    async fn test_service_line_item_id_doesnt_exist() {
+        let cmd = DeleteLineItemCommand::get_cmd();
+
+        let s = DeleteLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.delete_line_item(cmd.clone()).await,
+            Err(BillingError::LineItemIDNotFound)
+        );
+    }
+}

src/billing/application/services/errors.rs

@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_more::{Display, Error};
+use log::error;
+use serde::{Deserialize, Serialize};
+
+use crate::billing::application::port::output::db::errors::BillingDBError;
+
+pub type BillingResult<V> = Result<V, BillingError>;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum BillingError {
+    BillIDNotFound,
+    InternalError,
+    DuplicateStoreName,
+    StoreIDNotFound,
+    LineItemIDNotFound,
+}
+
+impl From<BillingDBError> for BillingError {
+    fn from(value: BillingDBError) -> Self {
+        match value {
+            BillingDBError::DuplicateBillID => {
+                error!("DuplicateBillID");
+                Self::InternalError
+            }
+            BillingDBError::DuplicateStoreName => Self::DuplicateStoreName,
+            BillingDBError::DuplicateStoreID => {
+                error!("DuplicateStoreID");
+                Self::InternalError
+            }
+            BillingDBError::StoreIDNotFound => BillingError::StoreIDNotFound,
+            BillingDBError::InternalError => BillingError::InternalError,
+            BillingDBError::DuplicateLineItemID => {
+                error!("DuplicateLineItemID");
+                Self::InternalError
+            }
+            BillingDBError::LineItemIDNotFound => BillingError::LineItemIDNotFound,
+        }
+    }
+}

src/billing/application/services/mod.rs

@@ -1,3 +1,71 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+
+pub mod errors;
+
+// services
+pub mod add_bill_service;
+pub mod add_line_item_service;
+pub mod add_store_service;
+pub mod delete_bill_service;
+pub mod delete_line_item_service;
+pub mod update_bill_service;
+pub mod update_line_item_service;
+pub mod update_store_service;
+
+#[automock]
+pub trait BillingServicesInterface: Send + Sync {
+    fn add_bill(&self) -> add_bill_service::AddBillServiceObj;
+    fn update_bill(&self) -> update_bill_service::UpdateBillServiceObj;
+    fn delete_bill(&self) -> delete_bill_service::DeleteBillServiceObj;
+    fn add_store(&self) -> add_store_service::AddStoreServiceObj;
+    fn update_store(&self) -> update_store_service::UpdateStoreServiceObj;
+    fn add_line_item(&self) -> add_line_item_service::AddLineItemServiceObj;
+    fn update_line_item(&self) -> update_line_item_service::UpdateLineItemServiceObj;
+    fn delete_line_item(&self) -> delete_line_item_service::DeleteLineItemServiceObj;
+}
+
+#[derive(Clone, Builder)]
+pub struct BillingServices {
+    add_bill: add_bill_service::AddBillServiceObj,
+    add_store: add_store_service::AddStoreServiceObj,
+    update_store: update_store_service::UpdateStoreServiceObj,
+    add_line_item: add_line_item_service::AddLineItemServiceObj,
+    update_line_item: update_line_item_service::UpdateLineItemServiceObj,
+    delete_line_item: delete_line_item_service::DeleteLineItemServiceObj,
+    update_bill: update_bill_service::UpdateBillServiceObj,
+    delete_bill: delete_bill_service::DeleteBillServiceObj,
+}
+
+impl BillingServicesInterface for BillingServices {
+    fn add_bill(&self) -> add_bill_service::AddBillServiceObj {
+        self.add_bill.clone()
+    }
+    fn update_bill(&self) -> update_bill_service::UpdateBillServiceObj {
+        self.update_bill.clone()
+    }
+    fn delete_bill(&self) -> delete_bill_service::DeleteBillServiceObj {
+        self.delete_bill.clone()
+    }
+
+    fn add_store(&self) -> add_store_service::AddStoreServiceObj {
+        self.add_store.clone()
+    }
+    fn update_store(&self) -> update_store_service::UpdateStoreServiceObj {
+        self.update_store.clone()
+    }
+    fn add_line_item(&self) -> add_line_item_service::AddLineItemServiceObj {
+        self.add_line_item.clone()
+    }
+    fn update_line_item(&self) -> update_line_item_service::UpdateLineItemServiceObj {
+        self.update_line_item.clone()
+    }
+    fn delete_line_item(&self) -> delete_line_item_service::DeleteLineItemServiceObj {
+        self.delete_line_item.clone()
+    }
+}

src/billing/application/services/update_bill_service.rs

@@ -0,0 +1,116 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::bill_id_exists::*,
+    domain::{bill_aggregate::*, bill_updated_event::*, update_bill_command::UpdateBillCommand},
+};
+
+#[automock]
+#[async_trait::async_trait]
+pub trait UpdateBillUseCase: Send + Sync {
+    async fn update_bill(&self, cmd: UpdateBillCommand) -> BillingResult<BillUpdatedEvent>;
+}
+
+pub type UpdateBillServiceObj = Arc<dyn UpdateBillUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct UpdateBillService {
+    db_bill_id_exists: BillIDExistsDBPortObj,
+}
+
+#[async_trait::async_trait]
+impl UpdateBillUseCase for UpdateBillService {
+    async fn update_bill(&self, cmd: UpdateBillCommand) -> BillingResult<BillUpdatedEvent> {
+        if !self
+            .db_bill_id_exists
+            .bill_id_exists(cmd.old_bill().bill_id())
+            .await?
+        {
+            return Err(BillingError::BillIDNotFound);
+        }
+
+        let bill = BillBuilder::default()
+            .bill_id(*cmd.old_bill().bill_id())
+            .token_number(*cmd.old_bill().token_number())
+            .total_price(cmd.total_price().clone())
+            .store_id(*cmd.store_id())
+            .deleted(false)
+            .build()
+            .unwrap();
+
+        Ok(BillUpdatedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .new_bill(bill)
+            .old_bill(cmd.old_bill().clone())
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::billing::domain::bill_updated_event::tests::get_updated_bill_event_from_command;
+    use crate::tests::bdd::*;
+    use crate::utils::uuid::tests::*;
+
+    pub fn mock_update_bill_service(
+        times: Option<usize>,
+        cmd: UpdateBillCommand,
+    ) -> UpdateBillServiceObj {
+        let mut m = MockUpdateBillUseCase::new();
+
+        let res = get_updated_bill_event_from_command(&cmd);
+
+        if let Some(times) = times {
+            m.expect_update_bill()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_update_bill().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service() {
+        let cmd = UpdateBillCommand::get_cmd();
+
+        let s = UpdateBillServiceBuilder::default()
+            .db_bill_id_exists(mock_bill_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.update_bill(cmd.clone()).await.unwrap();
+        assert_eq!(res.new_bill().total_price(), cmd.total_price());
+        assert_eq!(res.new_bill().bill_id(), cmd.old_bill().bill_id());
+        assert_eq!(res.old_bill(), cmd.old_bill());
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+
+    #[actix_rt::test]
+    async fn test_service_bill_id_doesnt_exist() {
+        let cmd = UpdateBillCommand::get_cmd();
+
+        let s = UpdateBillServiceBuilder::default()
+            .db_bill_id_exists(mock_bill_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.update_bill(cmd.clone()).await,
+            Err(BillingError::BillIDNotFound)
+        );
+    }
+}

src/billing/application/services/update_line_item_service.rs

@@ -0,0 +1,161 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+use time::OffsetDateTime;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::bill_id_exists::*,
+    application::port::output::db::line_item_id_exists::*,
+    domain::{line_item_aggregate::*, line_item_updated_event::*, update_line_item_command::*},
+};
+use crate::utils::uuid::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait UpdateLineItemUseCase: Send + Sync {
+    async fn update_line_item(
+        &self,
+        cmd: UpdateLineItemCommand,
+    ) -> BillingResult<LineItemUpdatedEvent>;
+}
+
+pub type UpdateLineItemServiceObj = Arc<dyn UpdateLineItemUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct UpdateLineItemService {
+    db_line_item_id_exists: LineItemIDExistsDBPortObj,
+    db_bill_id_exists: BillIDExistsDBPortObj,
+}
+
+#[async_trait::async_trait]
+impl UpdateLineItemUseCase for UpdateLineItemService {
+    async fn update_line_item(
+        &self,
+        cmd: UpdateLineItemCommand,
+    ) -> BillingResult<LineItemUpdatedEvent> {
+        if !self
+            .db_line_item_id_exists
+            .line_item_id_exists(cmd.old_line_item().line_item_id())
+            .await?
+        {
+            return Err(BillingError::LineItemIDNotFound);
+        }
+
+        if !self.db_bill_id_exists.bill_id_exists(cmd.bill_id()).await? {
+            return Err(BillingError::BillIDNotFound);
+        }
+
+        let new_line_item = LineItemBuilder::default()
+            .created_time(cmd.created_time().clone())
+            .product_name(cmd.product_name().into())
+            .product_id(*cmd.product_id())
+            .line_item_id(*cmd.old_line_item().line_item_id())
+            .bill_id(*cmd.bill_id())
+            .quantity(cmd.quantity().clone())
+            .price_per_unit(cmd.price_per_unit().clone())
+            .deleted(false)
+            .build()
+            .unwrap();
+
+        Ok(LineItemUpdatedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .new_line_item(new_line_item)
+            .old_line_item(cmd.old_line_item().clone())
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::billing::domain::line_item_updated_event::tests::get_updated_line_item_event_from_command;
+    use crate::utils::uuid::tests::UUID;
+    use crate::{tests::bdd::*, utils::uuid::tests::mock_get_uuid};
+
+    pub fn mock_update_line_item_service(
+        times: Option<usize>,
+        cmd: UpdateLineItemCommand,
+    ) -> UpdateLineItemServiceObj {
+        let mut m = MockUpdateLineItemUseCase::new();
+
+        let res = get_updated_line_item_event_from_command(&cmd);
+        if let Some(times) = times {
+            m.expect_update_line_item()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_update_line_item()
+                .returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service() {
+        let cmd = UpdateLineItemCommand::get_cmd();
+
+        let s = UpdateLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .db_bill_id_exists(mock_bill_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.update_line_item(cmd.clone()).await.unwrap();
+        assert_eq!(res.new_line_item().product_name(), cmd.product_name());
+        assert_eq!(res.new_line_item().product_id(), cmd.product_id());
+        assert_eq!(res.new_line_item().quantity(), cmd.quantity());
+        assert_eq!(
+            res.new_line_item().line_item_id(),
+            cmd.old_line_item().line_item_id()
+        );
+        assert_eq!(res.new_line_item().bill_id(), cmd.old_line_item().bill_id());
+
+        assert!(!res.new_line_item().deleted());
+
+        assert_eq!(res.old_line_item(), cmd.old_line_item());
+
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+
+    #[actix_rt::test]
+    async fn test_service_line_item_id_doesnt_exist() {
+        let cmd = UpdateLineItemCommand::get_cmd();
+
+        let s = UpdateLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .db_bill_id_exists(mock_bill_id_exists_db_port_true(IS_NEVER_CALLED))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.update_line_item(cmd.clone()).await,
+            Err(BillingError::LineItemIDNotFound)
+        );
+    }
+
+    #[actix_rt::test]
+    async fn test_service_bill_id_doesnt_exist() {
+        let cmd = UpdateLineItemCommand::get_cmd();
+
+        let s = UpdateLineItemServiceBuilder::default()
+            .db_line_item_id_exists(mock_line_item_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .db_bill_id_exists(mock_bill_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.update_line_item(cmd.clone()).await,
+            Err(BillingError::BillIDNotFound)
+        );
+    }
+}

src/billing/application/services/update_store_service.rs

@@ -0,0 +1,146 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::sync::Arc;
+
+use derive_builder::Builder;
+use mockall::predicate::*;
+use mockall::*;
+
+use super::errors::*;
+use crate::billing::{
+    application::port::output::db::{store_id_exists::*, store_name_exists::*},
+    domain::{
+        store_aggregate::*, store_updated_event::*, update_store_command::UpdateStoreCommand,
+    },
+};
+use crate::utils::uuid::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait UpdateStoreUseCase: Send + Sync {
+    async fn update_store(&self, cmd: UpdateStoreCommand) -> BillingResult<StoreUpdatedEvent>;
+}
+
+pub type UpdateStoreServiceObj = Arc<dyn UpdateStoreUseCase>;
+
+#[derive(Clone, Builder)]
+pub struct UpdateStoreService {
+    db_store_id_exists: StoreIDExistsDBPortObj,
+    db_store_name_exists: StoreNameExistsDBPortObj,
+}
+
+#[async_trait::async_trait]
+impl UpdateStoreUseCase for UpdateStoreService {
+    async fn update_store(&self, cmd: UpdateStoreCommand) -> BillingResult<StoreUpdatedEvent> {
+        if !self
+            .db_store_id_exists
+            .store_id_exists(cmd.old_store().store_id())
+            .await?
+        {
+            return Err(BillingError::StoreIDNotFound);
+        }
+
+        let store = StoreBuilder::default()
+            .name(cmd.name().into())
+            .address(cmd.address().as_ref().map(|s| s.to_string()))
+            .owner(*cmd.owner())
+            .store_id(*cmd.old_store().store_id())
+            .build()
+            .unwrap();
+
+        if cmd.name() != cmd.old_store().name() {
+            if self.db_store_name_exists.store_name_exists(&store).await? {
+                return Err(BillingError::DuplicateStoreName);
+            }
+        }
+
+        Ok(StoreUpdatedEventBuilder::default()
+            .added_by_user(*cmd.adding_by())
+            .new_store(store)
+            .old_store(cmd.old_store().clone())
+            .build()
+            .unwrap())
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use crate::billing::domain::store_updated_event::tests::get_store_updated_event_from_command;
+    use crate::billing::domain::update_store_command::tests::get_update_store_cmd;
+    use crate::tests::bdd::*;
+    use crate::utils::uuid::tests::*;
+
+    pub fn mock_update_store_service(
+        times: Option<usize>,
+        cmd: UpdateStoreCommand,
+    ) -> UpdateStoreServiceObj {
+        let mut m = MockUpdateStoreUseCase::new();
+
+        let res = get_store_updated_event_from_command(&cmd);
+
+        if let Some(times) = times {
+            m.expect_update_store()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_update_store().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
+    #[actix_rt::test]
+    async fn test_service() {
+        let cmd = get_update_store_cmd();
+
+        let s = UpdateStoreServiceBuilder::default()
+            .db_store_id_exists(mock_store_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .db_store_name_exists(mock_store_name_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        let res = s.update_store(cmd.clone()).await.unwrap();
+        assert_eq!(res.new_store().name(), cmd.name());
+        assert_eq!(res.new_store().address(), cmd.address());
+        assert_eq!(res.new_store().owner(), cmd.owner());
+        assert_eq!(res.new_store().store_id(), cmd.old_store().store_id());
+        assert_eq!(res.old_store(), cmd.old_store());
+        assert_eq!(res.added_by_user(), cmd.adding_by());
+    }
+
+    #[actix_rt::test]
+    async fn test_service_store_name_exists() {
+        let cmd = get_update_store_cmd();
+
+        let s = UpdateStoreServiceBuilder::default()
+            .db_store_id_exists(mock_store_id_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .db_store_name_exists(mock_store_name_exists_db_port_true(IS_CALLED_ONLY_ONCE))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.update_store(cmd.clone()).await,
+            Err(BillingError::DuplicateStoreName)
+        );
+    }
+
+    #[actix_rt::test]
+    async fn test_service_store_id_doesnt_exist() {
+        let cmd = get_update_store_cmd();
+
+        let s = UpdateStoreServiceBuilder::default()
+            .db_store_id_exists(mock_store_id_exists_db_port_false(IS_CALLED_ONLY_ONCE))
+            .db_store_name_exists(mock_store_name_exists_db_port_false(IS_NEVER_CALLED))
+            .build()
+            .unwrap();
+
+        assert_eq!(
+            s.update_store(cmd.clone()).await,
+            Err(BillingError::StoreIDNotFound)
+        );
+    }
+}

src/billing/domain/add_bill_command.rs

@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use derive_more::{Display, Error};
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use crate::types::{currency::*, quantity::*};
+use crate::utils::string::empty_string_err;
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters, Builder,
+)]
+pub struct AddBillCommand {
+    adding_by: Uuid,
+
+    #[builder(default = "OffsetDateTime::now_utc()")]
+    created_time: OffsetDateTime,
+
+    store_id: Uuid,
+}
+
+#[cfg(test)]
+mod tests {
+    use time::macros::datetime;
+
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    impl AddBillCommand {
+        pub fn get_cmd() -> Self {
+            let store_id = UUID;
+            let adding_by = UUID;
+
+            AddBillCommandBuilder::default()
+                .adding_by(adding_by)
+                .created_time(datetime!(1970-01-01 0:00 UTC))
+                .store_id(store_id)
+                .build()
+                .unwrap()
+        }
+    }
+
+    #[test]
+    fn test_cmd() {
+        let store_id = UUID;
+        let adding_by = UUID;
+
+        let cmd = AddBillCommandBuilder::default()
+            .adding_by(adding_by)
+            .store_id(store_id)
+            .build()
+            .unwrap();
+
+        assert_eq!(*cmd.store_id(), store_id);
+        assert_eq!(*cmd.adding_by(), adding_by);
+    }
+}

src/billing/domain/add_line_item_command.rs

@@ -0,0 +1,174 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use derive_more::{Display, Error};
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use crate::types::{currency::*, quantity::*};
+use crate::utils::string::empty_string_err;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum AddLineItemCommandError {
+    QuantityIsEmpty,
+    ProductNameIsEmpty,
+}
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters, Builder,
+)]
+pub struct UnvalidatedAddLineItemCommand {
+    adding_by: Uuid,
+
+    #[builder(default = "OffsetDateTime::now_utc()")]
+    created_time: OffsetDateTime,
+    product_name: String,
+    product_id: Uuid,
+    bill_id: Uuid,
+    quantity: Quantity,
+    price_per_unit: Price,
+}
+
+impl UnvalidatedAddLineItemCommand {
+    pub fn validate(self) -> Result<AddLineItemCommand, AddLineItemCommandError> {
+        let product_name = empty_string_err(
+            self.product_name,
+            AddLineItemCommandError::ProductNameIsEmpty,
+        )?;
+
+        if self.quantity.is_empty() {
+            return Err(AddLineItemCommandError::QuantityIsEmpty);
+        }
+
+        Ok(AddLineItemCommand {
+            created_time: self.created_time,
+            product_name,
+            product_id: self.product_id,
+            bill_id: self.bill_id,
+            quantity: self.quantity,
+            adding_by: self.adding_by,
+            price_per_unit: self.price_per_unit,
+        })
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters)]
+pub struct AddLineItemCommand {
+    created_time: OffsetDateTime,
+    product_name: String,
+    product_id: Uuid,
+    bill_id: Uuid,
+    quantity: Quantity,
+    price_per_unit: Price,
+
+    adding_by: Uuid,
+}
+
+#[cfg(test)]
+mod tests {
+    use time::macros::datetime;
+
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    impl AddLineItemCommand {
+        pub fn get_cmd() -> Self {
+            let product_name = "foo";
+            let product_id = UUID;
+            let bill_id = UUID;
+            let adding_by = UUID;
+            let quantity = Quantity::get_quantity();
+
+            UnvalidatedAddLineItemCommandBuilder::default()
+                .product_name(product_name.into())
+                .adding_by(adding_by)
+                .created_time(datetime!(1970-01-01 0:00 UTC))
+                .quantity(quantity.clone())
+                .price_per_unit(Price::default())
+                .product_id(product_id)
+                .bill_id(bill_id)
+                .build()
+                .unwrap()
+                .validate()
+                .unwrap()
+        }
+    }
+
+    #[test]
+    fn test_cmd() {
+        let product_name = "foo";
+        let product_id = UUID;
+        let bill_id = UUID;
+        let adding_by = UUID;
+        let quantity = Quantity::get_quantity();
+
+        let cmd = UnvalidatedAddLineItemCommandBuilder::default()
+            .product_name(product_name.into())
+            .adding_by(adding_by)
+            .price_per_unit(Price::default())
+            .quantity(quantity.clone())
+            .product_id(product_id)
+            .bill_id(bill_id)
+            .build()
+            .unwrap()
+            .validate()
+            .unwrap();
+
+        assert_eq!(cmd.quantity(), &quantity);
+        assert_eq!(*cmd.product_id(), product_id);
+        assert_eq!(*cmd.adding_by(), adding_by);
+        assert_eq!(cmd.product_name(), product_name);
+    }
+
+    #[test]
+    fn test_cmd_product_name_empty() {
+        let product_name = "";
+        let product_id = UUID;
+        let bill_id = UUID;
+        let adding_by = UUID;
+        let quantity = Quantity::get_quantity();
+
+        assert_eq!(
+            UnvalidatedAddLineItemCommandBuilder::default()
+                .product_name(product_name.into())
+                .adding_by(adding_by)
+                .quantity(quantity.clone())
+                .price_per_unit(Price::default())
+                .product_id(product_id)
+                .bill_id(bill_id)
+                .build()
+                .unwrap()
+                .validate(),
+            Err(AddLineItemCommandError::ProductNameIsEmpty)
+        );
+    }
+
+    #[test]
+    fn test_cmd_quantity_empty() {
+        let product_name = "foo";
+        let product_id = UUID;
+        let bill_id = UUID;
+        let adding_by = UUID;
+        // minor = 0; major = 0;
+        let quantity = Quantity::default();
+
+        assert_eq!(
+            UnvalidatedAddLineItemCommandBuilder::default()
+                .product_name(product_name.into())
+                .adding_by(adding_by)
+                .quantity(quantity.clone())
+                .product_id(product_id)
+                .bill_id(bill_id)
+                .price_per_unit(Price::default())
+                .build()
+                .unwrap()
+                .validate(),
+            Err(AddLineItemCommandError::QuantityIsEmpty)
+        );
+    }
+}

src/billing/domain/add_store_command.rs

@@ -0,0 +1,82 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_getters::Getters;
+use derive_more::{Display, Error};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum AddStoreCommandError {
+    NameIsEmpty,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters)]
+pub struct AddStoreCommand {
+    name: String,
+    address: Option<String>,
+    owner: Uuid,
+}
+
+impl AddStoreCommand {
+    pub fn new(
+        name: String,
+        address: Option<String>,
+        owner: Uuid,
+    ) -> Result<Self, AddStoreCommandError> {
+        let address: Option<String> = if let Some(address) = address {
+            let address = address.trim();
+            if address.is_empty() {
+                None
+            } else {
+                Some(address.to_owned())
+            }
+        } else {
+            None
+        };
+
+        let name = name.trim().to_owned();
+        if name.is_empty() {
+            return Err(AddStoreCommandError::NameIsEmpty);
+        }
+
+        Ok(Self {
+            name,
+            address,
+            owner,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    #[test]
+    fn test_cmd() {
+        let name = "foo";
+        let address = "bar";
+        let owner = UUID;
+
+        // address = None
+        let cmd = AddStoreCommand::new(name.into(), None, owner).unwrap();
+        assert_eq!(cmd.name(), name);
+        assert_eq!(cmd.address(), &None);
+        assert_eq!(cmd.owner(), &owner);
+
+        // address = Some
+        let cmd = AddStoreCommand::new(name.into(), Some(address.into()), owner).unwrap();
+        assert_eq!(cmd.name(), name);
+        assert_eq!(cmd.address(), &Some(address.to_owned()));
+        assert_eq!(cmd.owner(), &owner);
+
+        // AddStoreCommandError::NameIsEmpty
+        assert_eq!(
+            AddStoreCommand::new("".into(), Some(address.into()), owner),
+            Err(AddStoreCommandError::NameIsEmpty)
+        )
+    }
+}

src/billing/domain/bill_added_event.rs

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::bill_aggregate::Bill;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct BillAddedEvent {
+    added_by_user: Uuid,
+
+    bill: Bill,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::add_bill_command::AddBillCommand;
+
+    use super::*;
+
+    pub fn get_added_bill_event_from_command(cmd: &AddBillCommand) -> BillAddedEvent {
+        let bill = Bill::get_bill();
+
+        BillAddedEventBuilder::default()
+            .added_by_user(cmd.adding_by().clone())
+            .bill(bill)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn test_event() {
+        get_added_bill_event_from_command(&AddBillCommand::get_cmd());
+    }
+}

src/billing/domain/bill_aggregate.rs

@@ -0,0 +1,193 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::Aggregate;
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use crate::types::currency::*;
+
+use crate::billing::{
+    application::services::{errors::*, *},
+    domain::{commands::*, events::*},
+};
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Builder, Getters,
+)]
+pub struct Bill {
+    #[builder(default = "OffsetDateTime::now_utc()")]
+    created_time: OffsetDateTime,
+    //    bills: Vec<Bill>,
+    bill_id: Uuid,
+    token_number: usize,
+    #[builder(default = "None")]
+    total_price: Option<Price>,
+    store_id: Uuid,
+
+    #[builder(default = "false")]
+    deleted: bool,
+}
+
+impl Default for Bill {
+    fn default() -> Self {
+        Self {
+            created_time: OffsetDateTime::now_utc(),
+            bill_id: Default::default(),
+            token_number: 1,
+            total_price: None,
+            store_id: Uuid::new_v4(),
+            deleted: false,
+        }
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::{billing::domain::add_bill_command::AddBillCommand, utils::uuid::tests::UUID};
+
+    use super::*;
+
+    impl Bill {
+        pub fn get_bill() -> Self {
+            let cmd = AddBillCommand::get_cmd();
+
+            BillBuilder::default()
+                .created_time(cmd.created_time().clone())
+                .bill_id(UUID)
+                .store_id(UUID)
+                .token_number(1)
+                .build()
+                .unwrap()
+        }
+    }
+}
+//
+#[async_trait]
+impl Aggregate for Bill {
+    type Command = BillingCommand;
+    type Event = BillingEvent;
+    type Error = BillingError;
+    type Services = std::sync::Arc<dyn BillingServicesInterface>;
+
+    // This identifier should be unique to the system.
+    fn aggregate_type() -> String {
+        "billing.bill".to_string()
+    }
+
+    // The aggregate logic goes here. Note that this will be the _bulk_ of a CQRS system
+    // so expect to use helper functions elsewhere to keep the code clean.
+    async fn handle(
+        &self,
+        command: Self::Command,
+        services: &Self::Services,
+    ) -> Result<Vec<Self::Event>, Self::Error> {
+        match command {
+            BillingCommand::AddBill(cmd) => {
+                let res = services.add_bill().add_bill(cmd).await?;
+                Ok(vec![BillingEvent::BillAdded(res)])
+            }
+            BillingCommand::UpdateBill(cmd) => {
+                let res = services.update_bill().update_bill(cmd).await?;
+                Ok(vec![BillingEvent::BillUpdated(res)])
+            }
+            BillingCommand::DeleteBill(cmd) => {
+                let res = services.delete_bill().delete_bill(cmd).await?;
+                Ok(vec![BillingEvent::BillDeleted(res)])
+            }
+            _ => Ok(Vec::default()),
+        }
+    }
+
+    fn apply(&mut self, event: Self::Event) {
+        match event {
+            BillingEvent::BillAdded(e) => *self = e.bill().clone(),
+            BillingEvent::BillUpdated(e) => *self = e.new_bill().clone(),
+            BillingEvent::BillDeleted(e) => *self = e.bill().clone(),
+            _ => (),
+        }
+    }
+}
+
+#[cfg(test)]
+mod aggregate_tests {
+    use std::sync::Arc;
+
+    use add_bill_service::tests::mock_add_bill_service;
+    use cqrs_es::test::TestFramework;
+    use delete_bill_service::tests::mock_delete_bill_service;
+    use update_bill_service::tests::mock_update_bill_service;
+
+    use super::*;
+
+    use crate::billing::domain::bill_deleted_event::tests::get_deleted_bill_event_from_command;
+    use crate::billing::domain::bill_updated_event::tests::get_updated_bill_event_from_command;
+    use crate::billing::domain::delete_bill_command::DeleteBillCommand;
+    use crate::billing::domain::update_bill_command::UpdateBillCommand;
+    use crate::tests::bdd::*;
+
+    use crate::billing::domain::{
+        add_bill_command::*, bill_added_event::tests::get_added_bill_event_from_command,
+    };
+
+    type BillTestFramework = TestFramework<Bill>;
+
+    #[test]
+    fn test_add_bill() {
+        let cmd = AddBillCommand::get_cmd();
+        let expected = get_added_bill_event_from_command(&cmd);
+        let expected = BillingEvent::BillAdded(expected);
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_add_bill()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_add_bill_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        BillTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::AddBill(cmd))
+            .then_expect_events(vec![expected]);
+    }
+
+    #[test]
+    fn test_update_bill() {
+        let cmd = UpdateBillCommand::get_cmd();
+        let expected = get_updated_bill_event_from_command(&cmd);
+        let expected = BillingEvent::BillUpdated(expected);
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_update_bill()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_update_bill_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        BillTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::UpdateBill(cmd))
+            .then_expect_events(vec![expected]);
+    }
+
+    #[test]
+    fn test_delete_bill() {
+        let cmd = DeleteBillCommand::get_cmd();
+        let expected = get_deleted_bill_event_from_command(&cmd);
+        let expected = BillingEvent::BillDeleted(expected);
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_delete_bill()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_delete_bill_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        BillTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::DeleteBill(cmd))
+            .then_expect_events(vec![expected]);
+    }
+}

src/billing/domain/bill_deleted_event.rs

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::bill_aggregate::*;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct BillDeletedEvent {
+    added_by_user: Uuid,
+
+    bill: Bill,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::delete_bill_command::DeleteBillCommand;
+
+    use super::*;
+
+    pub fn get_deleted_bill_event_from_command(cmd: &DeleteBillCommand) -> BillDeletedEvent {
+        let deleted_bill = BillBuilder::default()
+            .created_time(cmd.bill().created_time().clone())
+            .store_id(*cmd.bill().store_id())
+            .bill_id(*cmd.bill().bill_id())
+            .token_number(1)
+            .deleted(true)
+            .build()
+            .unwrap();
+
+        BillDeletedEventBuilder::default()
+            .added_by_user(cmd.adding_by().clone())
+            .bill(deleted_bill)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn test_event() {
+        let event = get_deleted_bill_event_from_command(&DeleteBillCommand::get_cmd());
+        assert!(event.bill().deleted());
+    }
+}

src/billing/domain/bill_updated_event.rs

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::bill_aggregate::*;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct BillUpdatedEvent {
+    added_by_user: Uuid,
+
+    new_bill: Bill,
+    old_bill: Bill,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::update_bill_command::UpdateBillCommand;
+
+    use super::*;
+
+    pub fn get_updated_bill_event_from_command(cmd: &UpdateBillCommand) -> BillUpdatedEvent {
+        let new_bill = BillBuilder::default()
+            .created_time(cmd.created_time().clone())
+            .token_number(1)
+            .store_id(*cmd.store_id())
+            .bill_id(*cmd.old_bill().bill_id())
+            .build()
+            .unwrap();
+
+        BillUpdatedEventBuilder::default()
+            .added_by_user(cmd.adding_by().clone())
+            .old_bill(cmd.old_bill().clone())
+            .new_bill(new_bill)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn test_event() {
+        get_updated_bill_event_from_command(&UpdateBillCommand::get_cmd());
+    }
+}

src/billing/domain/commands.rs

@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use serde::{Deserialize, Serialize};
+
+use super::{
+    add_bill_command::AddBillCommand, add_line_item_command::AddLineItemCommand,
+    add_store_command::AddStoreCommand, delete_bill_command::DeleteBillCommand,
+    delete_line_item_command::DeleteLineItemCommand, update_bill_command::UpdateBillCommand,
+    update_line_item_command::UpdateLineItemCommand, update_store_command::UpdateStoreCommand,
+};
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd)]
+pub enum BillingCommand {
+    AddLineItem(AddLineItemCommand),
+    UpdateLineItem(UpdateLineItemCommand),
+    DeleteLineItem(DeleteLineItemCommand),
+    AddBill(AddBillCommand),
+    UpdateBill(UpdateBillCommand),
+    DeleteBill(DeleteBillCommand),
+    AddStore(AddStoreCommand),
+    UpdateStore(UpdateStoreCommand),
+}

src/billing/domain/delete_bill_command.rs

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::bill_aggregate::Bill;
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Builder, Getters,
+)]
+pub struct DeleteBillCommand {
+    adding_by: Uuid,
+    bill: Bill,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    impl DeleteBillCommand {
+        pub fn get_cmd() -> Self {
+            let adding_by = UUID;
+
+            DeleteBillCommandBuilder::default()
+                .adding_by(adding_by)
+                .bill(Bill::get_bill())
+                .build()
+                .unwrap()
+        }
+    }
+}

src/billing/domain/delete_line_item_command.rs

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::line_item_aggregate::LineItem;
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Builder, Getters,
+)]
+pub struct DeleteLineItemCommand {
+    adding_by: Uuid,
+    line_item: LineItem,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    impl DeleteLineItemCommand {
+        pub fn get_cmd() -> Self {
+            let adding_by = UUID;
+
+            DeleteLineItemCommandBuilder::default()
+                .adding_by(adding_by)
+                .line_item(LineItem::get_line_item())
+                .build()
+                .unwrap()
+        }
+    }
+}

src/billing/domain/events.rs

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use cqrs_es::DomainEvent;
+use serde::{Deserialize, Serialize};
+
+use super::{
+    bill_added_event::BillAddedEvent, bill_deleted_event::BillDeletedEvent,
+    bill_updated_event::BillUpdatedEvent, line_item_added_event::LineItemAddedEvent,
+    line_item_deleted_event::LineItemDeletedEvent, line_item_updated_event::LineItemUpdatedEvent,
+    store_added_event::StoreAddedEvent, store_updated_event::StoreUpdatedEvent,
+};
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd)]
+pub enum BillingEvent {
+    LineItemAdded(LineItemAddedEvent),
+    LineItemUpdated(LineItemUpdatedEvent),
+    LineItemDeleted(LineItemDeletedEvent),
+    BillAdded(BillAddedEvent),
+    BillUpdated(BillUpdatedEvent),
+    BillDeleted(BillDeletedEvent),
+    StoreAdded(StoreAddedEvent),
+    StoreUpdated(StoreUpdatedEvent),
+}
+
+impl DomainEvent for BillingEvent {
+    fn event_version(&self) -> String {
+        "1.0".to_string()
+    }
+
+    fn event_type(&self) -> String {
+        let e: &str = match self {
+            BillingEvent::LineItemAdded { .. } => "BillingLineItemAdded",
+            BillingEvent::LineItemUpdated { .. } => "BillingLineItemUpdated",
+            BillingEvent::LineItemDeleted { .. } => "BillingLineItemDeleted",
+            BillingEvent::BillAdded { .. } => "BillingBilAdded",
+            BillingEvent::BillUpdated { .. } => "BillingBilUpdated",
+            BillingEvent::BillDeleted { .. } => "BillingBilDeleted",
+            BillingEvent::StoreAdded { .. } => "BillingStoreAdded",
+            BillingEvent::StoreUpdated { .. } => "BillingStoreUpdated",
+        };
+
+        e.to_string()
+    }
+}

src/billing/domain/line_item_added_event.rs

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::line_item_aggregate::LineItem;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct LineItemAddedEvent {
+    added_by_user: Uuid,
+
+    line_item: LineItem,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::add_line_item_command::AddLineItemCommand;
+
+    use super::*;
+
+    pub fn get_added_line_item_event_from_command(cmd: &AddLineItemCommand) -> LineItemAddedEvent {
+        let line_item = LineItem::get_line_item();
+
+        LineItemAddedEventBuilder::default()
+            .added_by_user(cmd.adding_by().clone())
+            .line_item(line_item)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn test_event() {
+        get_added_line_item_event_from_command(&AddLineItemCommand::get_cmd());
+    }
+}

src/billing/domain/line_item_aggregate.rs

@@ -0,0 +1,219 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::Aggregate;
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use crate::billing::{
+    application::services::{errors::*, *},
+    domain::{commands::*, events::*},
+};
+use crate::types::{currency::Price, quantity::Quantity};
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Builder, Getters,
+)]
+pub struct LineItem {
+    #[builder(default = "OffsetDateTime::now_utc()")]
+    created_time: OffsetDateTime,
+    product_name: String,
+    product_id: Uuid,
+    bill_id: Uuid,
+    line_item_id: Uuid,
+    quantity: Quantity,
+    price_per_unit: Price,
+    #[builder(default = "false")]
+    deleted: bool,
+}
+
+impl Default for LineItem {
+    fn default() -> Self {
+        Self {
+            created_time: OffsetDateTime::now_utc(),
+            product_name: String::default(),
+            product_id: Default::default(),
+            line_item_id: Default::default(),
+            bill_id: Default::default(),
+            quantity: Default::default(),
+            price_per_unit: Price::default(),
+            deleted: false,
+        }
+    }
+}
+
+impl LineItem {
+    pub fn total_price(&self) -> Price {
+        let total_price_as_minor = (self.quantity().major_as_minor().unwrap() // TODO: handle err
+             + self.quantity().minor().number())
+            * (self.price_per_unit().major_as_minor() + self.price_per_unit().minor());
+
+        Price::from_minor(
+            total_price_as_minor,
+            self.price_per_unit().currency().clone(),
+        )
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::{
+        billing::domain::add_line_item_command::AddLineItemCommand, utils::uuid::tests::UUID,
+    };
+
+    use super::*;
+
+    impl LineItem {
+        pub fn get_line_item() -> Self {
+            let cmd = AddLineItemCommand::get_cmd();
+
+            LineItemBuilder::default()
+                .created_time(cmd.created_time().clone())
+                .product_name("test_product".into())
+                .product_id(*cmd.product_id())
+                .quantity(cmd.quantity().clone())
+                .bill_id(*cmd.bill_id())
+                .price_per_unit(cmd.price_per_unit().clone())
+                .line_item_id(UUID)
+                .build()
+                .unwrap()
+        }
+    }
+}
+
+#[async_trait]
+impl Aggregate for LineItem {
+    type Command = BillingCommand;
+    type Event = BillingEvent;
+    type Error = BillingError;
+    type Services = std::sync::Arc<dyn BillingServicesInterface>;
+
+    // This identifier should be unique to the system.
+    fn aggregate_type() -> String {
+        "billing.line_item".to_string()
+    }
+
+    // The aggregate logic goes here. Note that this will be the _bulk_ of a CQRS system
+    // so expect to use helper functions elsewhere to keep the code clean.
+    async fn handle(
+        &self,
+        command: Self::Command,
+        services: &Self::Services,
+    ) -> Result<Vec<Self::Event>, Self::Error> {
+        match command {
+            BillingCommand::AddLineItem(cmd) => {
+                let res = services.add_line_item().add_line_item(cmd).await?;
+                Ok(vec![BillingEvent::LineItemAdded(res)])
+            }
+            BillingCommand::UpdateLineItem(cmd) => {
+                let res = services.update_line_item().update_line_item(cmd).await?;
+                Ok(vec![BillingEvent::LineItemUpdated(res)])
+            }
+            BillingCommand::DeleteLineItem(cmd) => {
+                let res = services.delete_line_item().delete_line_item(cmd).await?;
+                Ok(vec![BillingEvent::LineItemDeleted(res)])
+            }
+            _ => Ok(Vec::default()),
+        }
+    }
+
+    fn apply(&mut self, event: Self::Event) {
+        match event {
+            BillingEvent::LineItemAdded(e) => *self = e.line_item().clone(),
+            BillingEvent::LineItemUpdated(e) => *self = e.new_line_item().clone(),
+            BillingEvent::LineItemDeleted(e) => *self = e.line_item().clone(),
+            _ => (),
+        }
+    }
+}
+
+#[cfg(test)]
+mod aggregate_tests {
+    use std::sync::Arc;
+
+    use add_line_item_service::tests::mock_add_line_item_service;
+    use cqrs_es::test::TestFramework;
+    use delete_line_item_service::tests::mock_delete_line_item_service;
+    use update_line_item_service::tests::mock_update_line_item_service;
+
+    use super::*;
+
+    use crate::billing::application::services::*;
+    use crate::billing::domain::delete_line_item_command::DeleteLineItemCommand;
+    use crate::billing::domain::line_item_deleted_event::tests::get_deleted_line_item_event_from_command;
+    use crate::billing::domain::line_item_updated_event::tests::get_updated_line_item_event_from_command;
+    use crate::billing::domain::update_line_item_command::UpdateLineItemCommand;
+    use crate::tests::bdd::*;
+
+    use crate::billing::domain::{
+        add_line_item_command::*,
+        line_item_added_event::tests::get_added_line_item_event_from_command,
+    };
+
+    type LineItemTestFramework = TestFramework<LineItem>;
+
+    #[test]
+    fn test_add_line_item() {
+        let cmd = AddLineItemCommand::get_cmd();
+        let expected = get_added_line_item_event_from_command(&cmd);
+        let expected = BillingEvent::LineItemAdded(expected);
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_add_line_item()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_add_line_item_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        LineItemTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::AddLineItem(cmd))
+            .then_expect_events(vec![expected]);
+    }
+
+    #[test]
+    fn test_update_line_item() {
+        let cmd = UpdateLineItemCommand::get_cmd();
+        let expected = get_updated_line_item_event_from_command(&cmd);
+        let expected = BillingEvent::LineItemUpdated(expected);
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_update_line_item()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_update_line_item_service(
+                IS_CALLED_ONLY_ONCE,
+                cmd.clone(),
+            ));
+
+        LineItemTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::UpdateLineItem(cmd))
+            .then_expect_events(vec![expected]);
+    }
+
+    #[test]
+    fn test_delete_line_item() {
+        let cmd = DeleteLineItemCommand::get_cmd();
+        let expected = get_deleted_line_item_event_from_command(&cmd);
+        let expected = BillingEvent::LineItemDeleted(expected);
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_delete_line_item()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_delete_line_item_service(
+                IS_CALLED_ONLY_ONCE,
+                cmd.clone(),
+            ));
+
+        LineItemTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::DeleteLineItem(cmd))
+            .then_expect_events(vec![expected]);
+    }
+}

src/billing/domain/line_item_deleted_event.rs

@@ -0,0 +1,54 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::line_item_aggregate::*;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct LineItemDeletedEvent {
+    added_by_user: Uuid,
+
+    line_item: LineItem,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::delete_line_item_command::DeleteLineItemCommand;
+
+    use super::*;
+
+    pub fn get_deleted_line_item_event_from_command(
+        cmd: &DeleteLineItemCommand,
+    ) -> LineItemDeletedEvent {
+        let deleted_line_item = LineItemBuilder::default()
+            .created_time(cmd.line_item().created_time().clone())
+            .product_name(cmd.line_item().product_name().into())
+            .product_id(*cmd.line_item().product_id())
+            .bill_id(*cmd.line_item().bill_id())
+            .line_item_id(*cmd.line_item().line_item_id())
+            .price_per_unit(cmd.line_item().price_per_unit().clone())
+            .quantity(cmd.line_item().quantity().clone())
+            .deleted(true)
+            .build()
+            .unwrap();
+
+        LineItemDeletedEventBuilder::default()
+            .added_by_user(cmd.adding_by().clone())
+            .line_item(deleted_line_item)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn test_event() {
+        let event = get_deleted_line_item_event_from_command(&DeleteLineItemCommand::get_cmd());
+        assert!(event.line_item().deleted());
+    }
+}

src/billing/domain/line_item_updated_event.rs

@@ -0,0 +1,54 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::line_item_aggregate::*;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct LineItemUpdatedEvent {
+    added_by_user: Uuid,
+
+    new_line_item: LineItem,
+    old_line_item: LineItem,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::update_line_item_command::UpdateLineItemCommand;
+
+    use super::*;
+
+    pub fn get_updated_line_item_event_from_command(
+        cmd: &UpdateLineItemCommand,
+    ) -> LineItemUpdatedEvent {
+        let new_line_item = LineItemBuilder::default()
+            .created_time(cmd.created_time().clone())
+            .product_name(cmd.product_name().clone())
+            .product_id(*cmd.product_id())
+            .bill_id(*cmd.bill_id())
+            .price_per_unit(cmd.price_per_unit().clone())
+            .quantity(cmd.quantity().clone())
+            .line_item_id(*cmd.old_line_item().line_item_id())
+            .build()
+            .unwrap();
+
+        LineItemUpdatedEventBuilder::default()
+            .added_by_user(cmd.adding_by().clone())
+            .old_line_item(cmd.old_line_item().clone())
+            .new_line_item(new_line_item)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn test_event() {
+        get_updated_line_item_event_from_command(&UpdateLineItemCommand::get_cmd());
+    }
+}

src/billing/domain/mod.rs

@@ -1,3 +1,30 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+
+// aggregates
+pub mod bill_aggregate;
+pub mod line_item_aggregate;
+pub mod store_aggregate;
+
+// commands
+pub mod add_bill_command;
+pub mod add_line_item_command;
+pub mod add_store_command;
+pub mod commands;
+pub mod delete_bill_command;
+pub mod delete_line_item_command;
+pub mod update_bill_command;
+pub mod update_line_item_command;
+pub mod update_store_command;
+
+// events;
+pub mod bill_added_event;
+pub mod bill_deleted_event;
+pub mod bill_updated_event;
+pub mod events;
+pub mod line_item_added_event;
+pub mod line_item_deleted_event;
+pub mod line_item_updated_event;
+pub mod store_added_event;
+pub mod store_updated_event;

src/billing/domain/store_added_event.rs

@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct StoreAddedEvent {
+    name: String,
+    address: Option<String>,
+    owner: Uuid,
+    store_id: Uuid,
+}

src/billing/domain/store_aggregate.rs

@@ -0,0 +1,146 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::Aggregate;
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use crate::billing::application::services::errors::*;
+use crate::billing::application::services::*;
+
+use super::{commands::BillingCommand, events::BillingEvent};
+
+#[derive(
+    Clone, Default, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Builder, Getters,
+)]
+pub struct Store {
+    name: String,
+    address: Option<String>,
+    owner: Uuid,
+    store_id: Uuid,
+    #[builder(default = "false")]
+    deleted: bool,
+}
+
+#[async_trait]
+impl Aggregate for Store {
+    type Command = BillingCommand;
+    type Event = BillingEvent;
+    type Error = BillingError;
+    type Services = std::sync::Arc<dyn BillingServicesInterface>;
+
+    // This identifier should be unique to the system.
+    fn aggregate_type() -> String {
+        "billing.store".to_string()
+    }
+
+    // The aggregate logic goes here. Note that this will be the _bulk_ of a CQRS system
+    // so expect to use helper functions elsewhere to keep the code clean.
+    async fn handle(
+        &self,
+        command: Self::Command,
+        services: &Self::Services,
+    ) -> Result<Vec<Self::Event>, Self::Error> {
+        match command {
+            BillingCommand::AddStore(cmd) => {
+                let res = services.add_store().add_store(cmd).await?;
+                Ok(vec![BillingEvent::StoreAdded(res)])
+            }
+            BillingCommand::UpdateStore(cmd) => {
+                let res = services.update_store().update_store(cmd).await?;
+                Ok(vec![BillingEvent::StoreUpdated(res)])
+            }
+
+            _ => Ok(Vec::default()),
+        }
+    }
+
+    fn apply(&mut self, event: Self::Event) {
+        match event {
+            BillingEvent::StoreAdded(e) => {
+                self.name = e.name().into();
+                self.address = e.address().as_ref().map(|s| s.to_string());
+                self.owner = *e.owner();
+                self.store_id = *e.store_id();
+                self.deleted = false;
+            }
+            BillingEvent::StoreUpdated(e) => *self = e.new_store().clone(),
+            _ => (),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::sync::Arc;
+
+    use cqrs_es::test::TestFramework;
+    use update_store_service::tests::mock_update_store_service;
+
+    use super::*;
+    use crate::billing::{
+        application::services::add_store_service::tests::*,
+        domain::{
+            add_store_command::*, commands::BillingCommand, events::BillingEvent,
+            store_added_event::*, store_updated_event::tests::get_store_updated_event_from_command,
+            update_store_command::tests::get_update_store_cmd,
+        },
+    };
+    use crate::tests::bdd::*;
+    use crate::utils::uuid::tests::*;
+
+    // A test framework that will apply our events and command
+    // and verify that the logic works as expected.
+    type StoreTestFramework = TestFramework<Store>;
+
+    #[test]
+    fn test_create_store() {
+        let name = "store_name";
+        let address = Some("store_address".to_string());
+        let owner = UUID;
+        let store_id = UUID;
+
+        let expected = StoreAddedEventBuilder::default()
+            .name(name.into())
+            .address(address.clone())
+            .store_id(store_id)
+            .owner(owner)
+            .build()
+            .unwrap();
+        let expected = BillingEvent::StoreAdded(expected);
+
+        let cmd = AddStoreCommand::new(name.into(), address.clone(), owner).unwrap();
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_add_store()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_add_store_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        StoreTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::AddStore(cmd))
+            .then_expect_events(vec![expected]);
+    }
+
+    #[test]
+    fn test_update_store() {
+        let cmd = get_update_store_cmd();
+        let expected = BillingEvent::StoreUpdated(get_store_updated_event_from_command(&cmd));
+
+        let mut services = MockBillingServicesInterface::new();
+        services
+            .expect_update_store()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_update_store_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        StoreTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(BillingCommand::UpdateStore(cmd))
+            .then_expect_events(vec![expected]);
+    }
+}

src/billing/domain/store_updated_event.rs

@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::store_aggregate::*;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct StoreUpdatedEvent {
+    added_by_user: Uuid,
+    old_store: Store,
+    new_store: Store,
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::billing::domain::update_store_command::UpdateStoreCommand;
+
+    use super::*;
+
+    pub fn get_store_updated_event_from_command(cmd: &UpdateStoreCommand) -> StoreUpdatedEvent {
+        let new_store = StoreBuilder::default()
+            .name(cmd.name().into())
+            .address(cmd.address().as_ref().map(|s| s.to_string()))
+            .owner(*cmd.owner())
+            .store_id(*cmd.old_store().store_id())
+            .build()
+            .unwrap();
+
+        StoreUpdatedEventBuilder::default()
+            .new_store(new_store)
+            .old_store(cmd.old_store().clone())
+            .added_by_user(*cmd.adding_by())
+            .build()
+            .unwrap()
+    }
+}

src/billing/domain/update_bill_command.rs

@@ -0,0 +1,71 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use super::bill_aggregate::Bill;
+use crate::types::currency::*;
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters, Builder,
+)]
+pub struct UpdateBillCommand {
+    adding_by: Uuid,
+
+    #[builder(default = "OffsetDateTime::now_utc()")]
+    created_time: OffsetDateTime,
+
+    store_id: Uuid,
+    token_number: usize,
+    total_price: Option<Price>,
+
+    old_bill: Bill,
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{billing::domain::bill_aggregate::*, utils::uuid::tests::UUID};
+
+    use super::*;
+
+    impl UpdateBillCommand {
+        pub fn get_cmd() -> Self {
+            let store_id = UUID;
+            let adding_by = UUID;
+
+            UpdateBillCommandBuilder::default()
+                .adding_by(adding_by)
+                .store_id(store_id)
+                .total_price(None)
+                .token_number(1)
+                .old_bill(Bill::get_bill())
+                .build()
+                .unwrap()
+        }
+    }
+
+    #[test]
+    fn test_cmd() {
+        let store_id = UUID;
+        let adding_by = UUID;
+        let old_bill = Bill::get_bill();
+
+        let cmd = UpdateBillCommandBuilder::default()
+            .adding_by(adding_by)
+            .store_id(store_id)
+            .total_price(None)
+            .token_number(1)
+            .old_bill(old_bill.clone())
+            .build()
+            .unwrap();
+
+        assert_eq!(*cmd.store_id(), store_id);
+        assert_eq!(*cmd.adding_by(), adding_by);
+        assert_eq!(cmd.old_bill(), &old_bill);
+    }
+}

src/billing/domain/update_line_item_command.rs

@@ -0,0 +1,185 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use derive_more::{Display, Error};
+use serde::{Deserialize, Serialize};
+use time::OffsetDateTime;
+use uuid::Uuid;
+
+use crate::types::{currency::*, quantity::*};
+use crate::utils::string::empty_string_err;
+
+use super::line_item_aggregate::LineItem;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum UpdateLineItemCommandError {
+    QuantityIsEmpty,
+    ProductNameIsEmpty,
+}
+
+#[derive(
+    Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters, Builder,
+)]
+pub struct UnvalidatedUpdateLineItemCommand {
+    adding_by: Uuid,
+
+    #[builder(default = "OffsetDateTime::now_utc()")]
+    created_time: OffsetDateTime,
+    product_name: String,
+    product_id: Uuid,
+    bill_id: Uuid,
+    quantity: Quantity,
+    price_per_unit: Price,
+
+    old_line_item: LineItem,
+}
+
+impl UnvalidatedUpdateLineItemCommand {
+    pub fn validate(self) -> Result<UpdateLineItemCommand, UpdateLineItemCommandError> {
+        let product_name = empty_string_err(
+            self.product_name,
+            UpdateLineItemCommandError::ProductNameIsEmpty,
+        )?;
+
+        if self.quantity.is_empty() {
+            return Err(UpdateLineItemCommandError::QuantityIsEmpty);
+        }
+
+        Ok(UpdateLineItemCommand {
+            created_time: self.created_time,
+            product_name,
+            product_id: self.product_id,
+            bill_id: self.bill_id,
+            quantity: self.quantity,
+            adding_by: self.adding_by,
+            old_line_item: self.old_line_item,
+            price_per_unit: self.price_per_unit,
+        })
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters)]
+pub struct UpdateLineItemCommand {
+    created_time: OffsetDateTime,
+    product_name: String,
+    product_id: Uuid,
+    bill_id: Uuid,
+    quantity: Quantity,
+    price_per_unit: Price,
+
+    old_line_item: LineItem,
+
+    adding_by: Uuid,
+}
+//
+#[cfg(test)]
+mod tests {
+    use crate::{billing::domain::bill_aggregate::Bill, utils::uuid::tests::UUID};
+
+    use super::*;
+
+    impl UpdateLineItemCommand {
+        pub fn get_cmd() -> Self {
+            let product_name = "foo";
+            let product_id = UUID;
+            let bill_id = UUID;
+            let adding_by = UUID;
+            let quantity = Quantity::get_quantity();
+
+            UnvalidatedUpdateLineItemCommandBuilder::default()
+                .product_name(product_name.into())
+                .adding_by(adding_by)
+                .quantity(quantity.clone())
+                .product_id(product_id)
+                .bill_id(product_id)
+                .old_line_item(LineItem::get_line_item())
+                .price_per_unit(Price::default())
+                .build()
+                .unwrap()
+                .validate()
+                .unwrap()
+        }
+    }
+
+    #[test]
+    fn test_cmd() {
+        let product_name = "foo";
+        let product_id = UUID;
+        let bill_id = UUID;
+        let adding_by = UUID;
+        let quantity = Quantity::get_quantity();
+        let old_line_item = LineItem::get_line_item();
+
+        let cmd = UnvalidatedUpdateLineItemCommandBuilder::default()
+            .product_name(product_name.into())
+            .adding_by(adding_by)
+            .quantity(quantity.clone())
+            .product_id(product_id)
+            .bill_id(bill_id)
+            .old_line_item(old_line_item.clone())
+            .price_per_unit(Price::default())
+            .build()
+            .unwrap()
+            .validate()
+            .unwrap();
+
+        assert_eq!(cmd.quantity(), &quantity);
+        assert_eq!(*cmd.product_id(), product_id);
+        assert_eq!(*cmd.bill_id(), bill_id);
+        assert_eq!(*cmd.adding_by(), adding_by);
+        assert_eq!(cmd.product_name(), product_name);
+        assert_eq!(cmd.old_line_item(), &old_line_item);
+    }
+
+    #[test]
+    fn test_cmd_product_name_empty() {
+        let product_name = "";
+        let product_id = UUID;
+        let bill_id = UUID;
+        let adding_by = UUID;
+        let quantity = Quantity::get_quantity();
+
+        assert_eq!(
+            UnvalidatedUpdateLineItemCommandBuilder::default()
+                .product_name(product_name.into())
+                .adding_by(adding_by)
+                .quantity(quantity.clone())
+                .product_id(product_id)
+                .bill_id(bill_id)
+                .price_per_unit(Price::default())
+                .old_line_item(LineItem::get_line_item())
+                .build()
+                .unwrap()
+                .validate(),
+            Err(UpdateLineItemCommandError::ProductNameIsEmpty)
+        );
+    }
+
+    #[test]
+    fn test_cmd_quantity_empty() {
+        let product_name = "foo";
+        let product_id = UUID;
+        let bill_id = UUID;
+        let adding_by = UUID;
+        // minor = 0; major = 0;
+        let quantity = Quantity::default();
+
+        assert_eq!(
+            UnvalidatedUpdateLineItemCommandBuilder::default()
+                .product_name(product_name.into())
+                .adding_by(adding_by)
+                .quantity(quantity.clone())
+                .product_id(product_id)
+                .bill_id(bill_id)
+                .old_line_item(LineItem::get_line_item())
+                .price_per_unit(Price::default())
+                .build()
+                .unwrap()
+                .validate(),
+            Err(UpdateLineItemCommandError::QuantityIsEmpty)
+        );
+    }
+}

src/billing/domain/update_store_command.rs

@@ -0,0 +1,127 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_getters::Getters;
+use derive_more::{Display, Error};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use super::store_aggregate::*;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum UpdateStoreCommandError {
+    NameIsEmpty,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters)]
+pub struct UpdateStoreCommand {
+    name: String,
+    address: Option<String>,
+    owner: Uuid,
+    old_store: Store,
+    adding_by: Uuid,
+}
+
+impl UpdateStoreCommand {
+    pub fn new(
+        name: String,
+        address: Option<String>,
+        owner: Uuid,
+        old_store: Store,
+        adding_by: Uuid,
+    ) -> Result<Self, UpdateStoreCommandError> {
+        let address: Option<String> = if let Some(address) = address {
+            let address = address.trim();
+            if address.is_empty() {
+                None
+            } else {
+                Some(address.to_owned())
+            }
+        } else {
+            None
+        };
+
+        let name = name.trim().to_owned();
+        if name.is_empty() {
+            return Err(UpdateStoreCommandError::NameIsEmpty);
+        }
+
+        Ok(Self {
+            name,
+            address,
+            owner,
+            old_store,
+            adding_by,
+        })
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::utils::uuid::tests::UUID;
+
+    use super::*;
+
+    pub fn get_update_store_cmd() -> UpdateStoreCommand {
+        let name = "foo";
+        let address = "bar";
+        let owner = UUID;
+        let adding_by = UUID;
+        let old_store = Store::default();
+
+        UpdateStoreCommand::new(
+            name.into(),
+            Some(address.into()),
+            owner,
+            old_store.clone(),
+            adding_by,
+        )
+        .unwrap()
+    }
+
+    #[test]
+    fn test_cmd() {
+        let name = "foo";
+        let address = "bar";
+        let owner = UUID;
+        let old_store = Store::default();
+        let adding_by = Uuid::new_v4();
+
+        // address = None
+        let cmd = UpdateStoreCommand::new(name.into(), None, owner, old_store.clone(), adding_by)
+            .unwrap();
+        assert_eq!(cmd.name(), name);
+        assert_eq!(cmd.address(), &None);
+        assert_eq!(cmd.owner(), &owner);
+        assert_eq!(cmd.old_store(), &old_store);
+        assert_eq!(cmd.adding_by(), &adding_by);
+
+        // address = Some
+        let cmd = UpdateStoreCommand::new(
+            name.into(),
+            Some(address.into()),
+            owner,
+            old_store.clone(),
+            adding_by,
+        )
+        .unwrap();
+        assert_eq!(cmd.name(), name);
+        assert_eq!(cmd.address(), &Some(address.to_owned()));
+        assert_eq!(cmd.owner(), &owner);
+        assert_eq!(cmd.old_store(), &old_store);
+        assert_eq!(cmd.adding_by(), &adding_by);
+
+        // UpdateStoreCommandError::NameIsEmpty
+        assert_eq!(
+            UpdateStoreCommand::new(
+                "".into(),
+                Some(address.into()),
+                owner,
+                old_store.clone(),
+                adding_by
+            ),
+            Err(UpdateStoreCommandError::NameIsEmpty)
+        )
+    }
+}