feat: add currency to accounts

internal/repository/account.go

@@ -3,11 +3,21 @@ package repository
 import (
 	"database/sql"
 	"errors"
+	"time"
 
 	"git.juancwu.dev/juancwu/budgit/internal/model"
 	"github.com/jmoiron/sqlx"
+	"github.com/shopspring/decimal"
 )
 
+// AllocationConversion describes the converted amount/target for a single
+// allocation row when an account's currency is changed.
+type AllocationConversion struct {
+	ID           string
+	Amount       decimal.Decimal
+	TargetAmount *decimal.Decimal
+}
+
 var ErrAccountNotFound = errors.New("account not found")
 
 type AccountRepository interface {
@@ -16,6 +26,9 @@ type AccountRepository interface {
 	BySpaceID(spaceID string) ([]*model.Account, error)
 	Rename(id, name string) error
 	Delete(id string) error
+	// ChangeCurrency atomically updates an account's currency and balance and
+	// rewrites each provided allocation's amount/target in the new currency.
+	ChangeCurrency(accountID, newCurrency string, newBalance decimal.Decimal, allocationConversions []AllocationConversion) error
 }
 
 type accountRepository struct {
@@ -27,9 +40,9 @@ func NewAccountRepository(db *sqlx.DB) AccountRepository {
 }
 
 func (r *accountRepository) Create(account *model.Account) error {
-	query := `INSERT INTO accounts (id, name, space_id, created_at, updated_at)
-	          VALUES ($1, $2, $3, $4, $5);`
-	_, err := r.db.Exec(query, account.ID, account.Name, account.SpaceID, account.CreatedAt, account.UpdatedAt)
+	query := `INSERT INTO accounts (id, name, space_id, currency, created_at, updated_at)
+	          VALUES ($1, $2, $3, $4, $5, $6);`
+	_, err := r.db.Exec(query, account.ID, account.Name, account.SpaceID, account.Currency, account.CreatedAt, account.UpdatedAt)
 	return err
 }
 
@@ -64,3 +77,24 @@ func (r *accountRepository) Delete(id string) error {
 	_, err := r.db.Exec(query, id)
 	return err
 }
+
+func (r *accountRepository) ChangeCurrency(accountID, newCurrency string, newBalance decimal.Decimal, allocationConversions []AllocationConversion) error {
+	return WithTx(r.db, func(tx *sqlx.Tx) error {
+		now := time.Now()
+		if _, err := tx.Exec(
+			`UPDATE accounts SET currency = $1, balance = $2, updated_at = $3 WHERE id = $4;`,
+			newCurrency, newBalance, now, accountID,
+		); err != nil {
+			return err
+		}
+		for _, c := range allocationConversions {
+			if _, err := tx.Exec(
+				`UPDATE allocations SET amount = $1, target_amount = $2, updated_at = $3 WHERE id = $4;`,
+				c.Amount, c.TargetAmount, now, c.ID,
+			); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}