package sql

import (
	"database/sql"
	"fmt"
)

func (c *conn) migrate() (int, error) {
	_, err := c.Exec(`
		create table if not exists migrations (
			num integer not null,
			at timestamptz not null
		);
	`)
	if err != nil {
		return 0, fmt.Errorf("creating migration table: %v", err)
	}

	i := 0
	done := false

	var flavorMigrations []migration
	for _, m := range migrations {
		if m.flavor == nil || m.flavor == c.flavor {
			flavorMigrations = append(flavorMigrations, m)
		}
	}

	for {
		err := c.ExecTx(func(tx *trans) error {
			// Within a transaction, perform a single migration.
			var (
				num sql.NullInt64
				n   int
			)
			if err := tx.QueryRow(`select max(num) from migrations;`).Scan(&num); err != nil {
				return fmt.Errorf("select max migration: %v", err)
			}
			if num.Valid {
				n = int(num.Int64)
			}
			if n >= len(flavorMigrations) {
				done = true
				return nil
			}

			migrationNum := n + 1
			m := flavorMigrations[n]
			for i := range m.stmts {
				if _, err := tx.Exec(m.stmts[i]); err != nil {
					return fmt.Errorf("migration %d statement %d failed: %v", migrationNum, i+1, err)
				}
			}

			q := `insert into migrations (num, at) values ($1, now());`
			if _, err := tx.Exec(q, migrationNum); err != nil {
				return fmt.Errorf("update migration table: %v", err)
			}
			return nil
		})
		if err != nil {
			return i, err
		}
		if done {
			break
		}
		i++
	}

	return i, nil
}

type migration struct {
	stmts []string

	// If flavor is nil the migration will take place for all database backend flavors.
	// If specified, only for that corresponding flavor, in that case stmts can be written
	// in the specific SQL dialect.
	flavor *flavor
}

// All SQL flavors share migration strategies.
var migrations = []migration{
	{
		stmts: []string{`
			create table client (
				id text not null primary key,
				secret text not null,
				redirect_uris bytea not null, -- JSON array of strings
				trusted_peers bytea not null, -- JSON array of strings
				public boolean not null,
				name text not null,
				logo_url text not null
			);`,
			`
			create table auth_request (
				id text not null primary key,
				client_id text not null,
				response_types bytea not null, -- JSON array of strings
				scopes bytea not null,         -- JSON array of strings
				redirect_uri text not null,
				nonce text not null,
				state text not null,
				force_approval_prompt boolean not null,

				logged_in boolean not null,

				claims_user_id text not null,
				claims_username text not null,
				claims_email text not null,
				claims_email_verified boolean not null,
				claims_groups bytea not null, -- JSON array of strings

				connector_id text not null,
				connector_data bytea,

				expiry timestamptz not null
			);`,
			`
			create table auth_code (
				id text not null primary key,
				client_id text not null,
				scopes bytea not null, -- JSON array of strings
				nonce text not null,
				redirect_uri text not null,

				claims_user_id text not null,
				claims_username text not null,
				claims_email text not null,
				claims_email_verified boolean not null,
				claims_groups bytea not null, -- JSON array of strings

				connector_id text not null,
				connector_data bytea,

				expiry timestamptz not null
			);`,
			`
			create table refresh_token (
				id text not null primary key,
				client_id text not null,
				scopes bytea not null, -- JSON array of strings
				nonce text not null,

				claims_user_id text not null,
				claims_username text not null,
				claims_email text not null,
				claims_email_verified boolean not null,
				claims_groups bytea not null, -- JSON array of strings

				connector_id text not null,
				connector_data bytea
			);`,
			`
			create table password (
				email text not null primary key,
				hash bytea not null,
				username text not null,
				user_id text not null
			);`,
			`
			-- keys is a weird table because we only ever expect there to be a single row
			create table keys (
				id text not null primary key,
				verification_keys bytea not null, -- JSON array
				signing_key bytea not null,       -- JSON object
				signing_key_pub bytea not null,   -- JSON object
				next_rotation timestamptz not null
			);`,
		},
	},
	{
		stmts: []string{`
			alter table refresh_token
				add column token text not null default '';`,
			`
			alter table refresh_token
				add column created_at timestamptz not null default '0001-01-01 00:00:00 UTC';`,
			`
			alter table refresh_token
				add column last_used timestamptz not null default '0001-01-01 00:00:00 UTC';`,
		},
	},
	{
		stmts: []string{`
			create table offline_session (
				user_id text not null,
				conn_id text not null,
				refresh bytea not null,
				PRIMARY KEY (user_id, conn_id)
			);`,
		},
	},
	{
		stmts: []string{`
			create table connector (
				id text not null primary key,
				type text not null,
				name text not null,
				resource_version text not null,
				config bytea
			);`,
		},
	},
	{
		stmts: []string{`
			alter table auth_code
				add column claims_preferred_username text not null default '';`,
			`
			alter table auth_request
				add column claims_preferred_username text not null default '';`,
			`
			alter table refresh_token
				add column claims_preferred_username text not null default '';`,
		},
	},
	{
		stmts: []string{`
			alter table offline_session
				add column connector_data bytea;
			`,
		},
	},
	{
		stmts: []string{`
			alter table auth_request
				modify column state varchar(4096);
			`,
		},
		flavor: &flavorMySQL,
	},
	{
		stmts: []string{`
			create table device_request (
				user_code text not null primary key,
				device_code text not null,
				client_id text not null,
				scopes bytea not null, -- JSON array of strings
				pkce_verifier text not null,
				expiry timestamptz not null
			);`,
			`
			create table device_token (
				device_code text not null primary key,
				status text not null,
				token text,
				expiry timestamptz not null
			);`,
		},
	},
}