feat: convert quantity to minor

src/types/quantity.rs

@@ -6,7 +6,7 @@ use std::str::FromStr;
 
 use derive_builder::Builder;
 use derive_getters::Getters;
-use derive_more::Display;
+use derive_more::{Display, Error};
 use serde::{Deserialize, Serialize};
 
 #[derive(
@@ -17,6 +17,9 @@ pub enum QuantityUnit {
     Kilogram,
     #[display(fmt = "{}", GRAM)]
     Gram,
+    #[display(fmt = "{}", MILLI_GRAM)]
+    Milligram,
+
     #[default]
     #[display(fmt = "{}", DISCRETE_NUMBER)]
     DiscreteNumber, // example: 1 sofa, 2 bed, etc.
@@ -28,6 +31,7 @@ pub enum QuantityUnit {
 
 const KILO_GRAM: &str = "kg";
 const GRAM: &str = "g";
+const MILLI_GRAM: &str = "mg";
 const DISCRETE_NUMBER: &str = "discrete_number";
 const MILLI_LITER: &str = "ml";
 const LITER: &str = "l";
@@ -41,6 +45,7 @@ impl FromStr for QuantityUnit {
             DISCRETE_NUMBER => Ok(Self::DiscreteNumber),
             MILLI_LITER => Ok(Self::MilliLiter),
             LITER => Ok(Self::Liter),
+            MILLI_GRAM => Ok(Self::Milligram),
             _ => Err("Currency unsupported".into()),
         }
     }
@@ -58,6 +63,17 @@ impl QuantityPart {
     pub fn is_empty(&self) -> bool {
         self.number == 0
     }
+
+    pub fn as_minor(&self) -> QuantityResult<usize> {
+        match self.unit {
+            QuantityUnit::Kilogram | QuantityUnit::Liter | QuantityUnit::Gram => {
+                Ok(self.number * 1000)
+            }
+            QuantityUnit::Milligram | QuantityUnit::MilliLiter | QuantityUnit::DiscreteNumber => {
+                Err(QuantityError::QuantityCantBeDivided)
+            }
+        }
+    }
 }
 
 #[derive(
@@ -67,11 +83,21 @@ pub struct Quantity {
     minor: QuantityPart,
     major: QuantityPart,
 }
+pub type QuantityResult<V> = Result<V, QuantityError>;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum QuantityError {
+    QuantityCantBeDivided,
+}
 
 impl Quantity {
     pub fn is_empty(&self) -> bool {
         self.minor.is_empty() == true && self.major.is_empty() == true
     }
+
+    pub fn major_as_minor(&self) -> QuantityResult<usize> {
+        self.major.as_minor()
+    }
 }
 
 #[cfg(test)]
@@ -180,6 +206,11 @@ mod tests {
         assert!(test_helper(QuantityUnit::Liter, LITER));
     }
 
+    #[test]
+    fn quantity_unit_milli_gram() {
+        assert!(test_helper(QuantityUnit::Milligram, MILLI_GRAM));
+    }
+
     impl Quantity {
         pub fn get_quantity() -> Self {
             let q = QuantityPartBuilder::default()
@@ -195,4 +226,65 @@ mod tests {
                 .unwrap()
         }
     }
+
+    #[test]
+    fn test_quantity_as_minor() {
+        assert_eq!(
+            QuantityPart {
+                unit: QuantityUnit::Kilogram,
+                number: 1
+            }
+            .as_minor()
+            .unwrap(),
+            1000
+        );
+
+        assert_eq!(
+            QuantityPart {
+                unit: QuantityUnit::Gram,
+                number: 1
+            }
+            .as_minor()
+            .unwrap(),
+            1000
+        );
+
+        assert_eq!(
+            QuantityPart {
+                unit: QuantityUnit::Liter,
+                number: 1
+            }
+            .as_minor()
+            .unwrap(),
+            1000
+        );
+
+        // error cases
+       assert_eq!(
+            QuantityPart {
+                unit: QuantityUnit::Milligram,
+                number: 1
+            }
+            .as_minor(),
+            Err(QuantityError::QuantityCantBeDivided)
+        );
+       assert_eq!(
+            QuantityPart {
+                unit: QuantityUnit::DiscreteNumber,
+                number: 1
+            }
+            .as_minor(),
+            Err(QuantityError::QuantityCantBeDivided)
+        );
+       assert_eq!(
+            QuantityPart {
+                unit: QuantityUnit::Milligram,
+                number: 1
+            }
+            .as_minor(),
+            Err(QuantityError::QuantityCantBeDivided)
+        );
+
+
+    }
 }