Add situation when transfer will be from one currency on the card to different currency

db/transfer.go

@@ -14,6 +14,9 @@ type Transfer struct {
 	ToCardID                uint
 	ToCard                  *Card
 	Value                   uint64
+	HaveDifferentCurrencies bool
+	FromValue               uint64
+	ToValue                 uint64
 	Date                    time.Time
 	UserID                  uint
 	User                    *User
@@ -36,34 +39,65 @@ func (t *Transfer) SetUserID(id uint) {
 
 var (
 	ERROR_TRANSFER_FROMCARD_INVALID_USERID       = errors.New("Transfer's UserID and FromCard's UserID are not equal")
-	ERROR_TRANSFER_FROMCARD_INSUFFICIENT_BALANCE = errors.New("FromCard's Balance is lower than Transfer's Value")
+	ERROR_TRANSFER_FROMCARD_INSUFFICIENT_BALANCE = errors.New("FromCard's Balance is lower than Transfer's Value or FromValue")
 	ERROR_TRANSFER_TOCARD_INVALID_USERID         = errors.New("Transfer's UserID and ToCard's UserID are not equal")
+	ERROR_TRANSFER_CURRENCY_INCOSISTENCE         = errors.New("Transfer is using differenct currencies but FromValue or ToValue is not set approprietly")
 )
 
+func (t *Transfer) validateTransfer(fromCard, toCard *Card) error {
+	if fromCard.UserID != t.UserID {
+		return ERROR_TRANSFER_FROMCARD_INVALID_USERID
+	}
+	if toCard.UserID != t.UserID {
+		return ERROR_TRANSFER_TOCARD_INVALID_USERID
+	}
+	diffCurs := fromCard.CurrencyID != toCard.CurrencyID
+	if diffCurs && (t.FromValue == 0 || t.ToValue == 0) {
+		return ERROR_TRANSFER_CURRENCY_INCOSISTENCE
+	}
+	if !diffCurs && fromCard.Balance < t.Value {
+		return ERROR_TRANSFER_FROMCARD_INSUFFICIENT_BALANCE
+	}
+	if diffCurs && fromCard.Balance < t.FromValue {
+		return ERROR_TRANSFER_FROMCARD_INSUFFICIENT_BALANCE
+	}
+	return nil
+}
+
 func (t *Transfer) BeforeCreate(tx *gorm.DB) error {
 	fromCard := &Card{}
 	if err := tx.Find(fromCard, t.FromCardID).Error; err != nil {
 		return err
 	}
-	if fromCard.UserID != t.UserID {
+	toCard := &Card{}
-		return ERROR_TRANSFER_FROMCARD_INVALID_USERID
+	if err := tx.Find(toCard, t.ToCardID).Error; err != nil {
+		return err
 	}
-	if fromCard.Balance < t.Value {
+	if err := t.validateTransfer(fromCard, toCard); err != nil {
-		return ERROR_TRANSFER_FROMCARD_INSUFFICIENT_BALANCE
+		return err
 	}
+
+	t.HaveDifferentCurrencies = fromCard.CurrencyID != toCard.CurrencyID
+	// on same CurrencyID fromCard and toCard should use Value
+	if !t.HaveDifferentCurrencies {
 		fromCard.Balance -= t.Value
 		if err := tx.Save(fromCard).Error; err != nil {
 			return err
 		}
 		//
-	toCard := &Card{}
+		toCard.Balance += t.Value
-	if err := tx.Find(toCard, t.ToCardID).Error; err != nil {
+		if err := tx.Save(toCard).Error; err != nil {
 			return err
 		}
-	if toCard.UserID != t.UserID {
+		return nil
-		return ERROR_TRANSFER_TOCARD_INVALID_USERID
 	}
-	toCard.Balance += t.Value
+	// on DIFFERENT CurrencyID fromCard should use FromValue and toCard should use ToValue
+	fromCard.Balance -= t.FromValue
+	if err := tx.Save(fromCard).Error; err != nil {
+		return err
+	}
+	//
+	toCard.Balance += t.ToValue
 	if err := tx.Save(toCard).Error; err != nil {
 		return err
 	}
@@ -71,39 +105,43 @@ func (t *Transfer) BeforeCreate(tx *gorm.DB) error {
 }
 
 var (
-	ERROR_TRANSFER_FROMCARD_IDZERO             = errors.New("Transfer's FromCardID is zero")
+	ERROR_TRANSFER_TOCARD_INSUFFICIENT_BALANCE = errors.New("Transfer's ToCard's Balance is lower than Value of ToValue of transfer")
-	ERROR_TRANSFER_TOCARD_IDZERO               = errors.New("Transfer's ToCardID is zero")
-	ERROR_TRANSFER_TOCARD_INSUFFICIENT_BALANCE = errors.New("Transfer's ToCard's Balance is lower than value of transfer")
 )
 
 func (t *Transfer) BeforeUpdate(tx *gorm.DB) error {
-	var original Transfer
+	var original *Transfer
-	if err := tx.Find(&original, t.ID).Error; err != nil {
+	if err := tx.Find(original, t.ID).Error; err != nil {
 		return err
 	}
-	if original.FromCardID == 0 {
+	var origFromCard *Card
-		return ERROR_TRANSFER_FROMCARD_IDZERO
+	if err := tx.Find(origFromCard, original.FromCardID).Error; err != nil {
-	}
-	var origFromCard Card
-	if err := tx.Find(&origFromCard, original.FromCardID).Error; err != nil {
 		return err
 	}
-	origFromCard.Balance += original.Value
+	var origToCard *Card
-	if err := tx.Save(origFromCard).Error; err != nil {
+	if err := tx.Find(origToCard, original.ToCardID).Error; err != nil {
 		return err
 	}
 
-	if original.ToCardID == 0 {
+	diffCurs := origFromCard.CurrencyID != origToCard.CurrencyID
-		return ERROR_TRANSFER_FROMCARD_IDZERO
+	if !diffCurs {
-	}
+		origFromCard.Balance += original.Value
-	var origToCard Card
-	if err := tx.Find(&origToCard, original.ToCardID).Error; err != nil {
-		return err
-	}
 		if origToCard.Balance < original.Value {
 			return ERROR_TRANSFER_TOCARD_INSUFFICIENT_BALANCE
 		}
 		origToCard.Balance -= original.Value
+	} else {
+		if original.FromValue == 0 || original.ToValue == 0 {
+			return ERROR_TRANSFER_CURRENCY_INCOSISTENCE
+		}
+		origFromCard.Balance += original.FromValue
+		if origToCard.Balance < original.ToValue {
+			return ERROR_TRANSFER_TOCARD_INSUFFICIENT_BALANCE
+		}
+		origToCard.Balance -= original.ToValue
+	}
+	if err := tx.Save(origFromCard).Error; err != nil {
+		return err
+	}
 	if err := tx.Save(origToCard).Error; err != nil {
 		return err
 	}
@@ -112,25 +150,35 @@ func (t *Transfer) BeforeUpdate(tx *gorm.DB) error {
 	if err := tx.Find(fromCard, t.FromCardID).Error; err != nil {
 		return err
 	}
-	if fromCard.UserID != t.UserID {
+	toCard := &Card{}
-		return ERROR_TRANSFER_FROMCARD_INVALID_USERID
+	if err := tx.Find(toCard, t.ToCardID).Error; err != nil {
+		return err
 	}
-	if fromCard.Balance < t.Value {
+	if err := t.validateTransfer(fromCard, toCard); err != nil {
-		return ERROR_TRANSFER_FROMCARD_INSUFFICIENT_BALANCE
+		return err
 	}
+
+	t.HaveDifferentCurrencies = fromCard.CurrencyID != toCard.CurrencyID
+	// on same CurrencyID fromCard and toCard should use Value
+	if !t.HaveDifferentCurrencies {
 		fromCard.Balance -= t.Value
 		if err := tx.Save(fromCard).Error; err != nil {
 			return err
 		}
 		//
-	toCard := &Card{}
+		toCard.Balance += t.Value
-	if err := tx.Find(toCard, t.ToCardID).Error; err != nil {
+		if err := tx.Save(toCard).Error; err != nil {
 			return err
 		}
-	if toCard.UserID != t.UserID {
+		return nil
-		return ERROR_TRANSFER_TOCARD_INVALID_USERID
 	}
-	toCard.Balance += t.Value
+	// on DIFFERENT CurrencyID fromCard should use FromValue and toCard should use ToValue
+	fromCard.Balance -= t.FromValue
+	if err := tx.Save(fromCard).Error; err != nil {
+		return err
+	}
+	//
+	toCard.Balance += t.ToValue
 	if err := tx.Save(toCard).Error; err != nil {
 		return err
 	}
@@ -142,18 +190,31 @@ func (t *Transfer) AfterDelete(tx *gorm.DB) error {
 	if err := tx.Find(fromCard, t.FromCardID).Error; err != nil {
 		return err
 	}
-	fromCard.Balance += t.Value
-	if err := tx.Save(fromCard).Error; err != nil {
-		return err
-	}
 	toCard := &Card{}
 	if err := tx.Find(toCard, t.ToCardID).Error; err != nil {
 		return err
 	}
+	diffCurs := fromCard.CurrencyID != toCard.CurrencyID
+	if !diffCurs {
+		fromCard.Balance += t.Value
 		if toCard.Balance < t.Value {
 			return ERROR_TRANSFER_TOCARD_INSUFFICIENT_BALANCE
 		}
 		toCard.Balance -= t.Value
+		return nil
+	} else {
+		if t.FromValue == 0 || t.ToValue == 0 {
+			return ERROR_TRANSFER_CURRENCY_INCOSISTENCE
+		}
+		fromCard.Balance += t.FromValue
+		if toCard.Balance < t.ToValue {
+			return ERROR_TRANSFER_TOCARD_INSUFFICIENT_BALANCE
+		}
+		toCard.Balance -= t.ToValue
+	}
+	if err := tx.Save(fromCard).Error; err != nil {
+		return err
+	}
 	if err := tx.Save(toCard).Error; err != nil {
 		return err
 	}