Reapply "feat(loyalty): EnakPoint & EnakCoin" (#32)

This reverts commit 4e24f9bbb0.

internal/repository/game_prize_repository.go

@@ -3,12 +3,16 @@ package repository
 import (
 	"apskel-pos-be/internal/entities"
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/google/uuid"
 	"gorm.io/gorm"
 )
 
+// ErrGamePrizeOutOfStock means a prize had less stock than was taken from it.
+var ErrGamePrizeOutOfStock = errors.New("game prize is out of stock")
+
 type GamePrizeRepository struct {
 	db *gorm.DB
 }
@@ -18,12 +22,12 @@ func NewGamePrizeRepository(db *gorm.DB) *GamePrizeRepository {
 }
 
 func (r *GamePrizeRepository) Create(ctx context.Context, gamePrize *entities.GamePrize) error {
-	return r.db.WithContext(ctx).Create(gamePrize).Error
+	return DBFromContext(ctx, r.db).WithContext(ctx).Create(gamePrize).Error
 }
 
 func (r *GamePrizeRepository) GetByID(ctx context.Context, id uuid.UUID) (*entities.GamePrize, error) {
 	var gamePrize entities.GamePrize
-	err := r.db.WithContext(ctx).Preload("Game").Preload("FallbackPrize").Where("id = ?", id).First(&gamePrize).Error
+	err := DBFromContext(ctx, r.db).WithContext(ctx).Preload("Game").Preload("FallbackPrize").Where("id = ?", id).First(&gamePrize).Error
 	if err != nil {
 		return nil, err
 	}
@@ -32,7 +36,7 @@ func (r *GamePrizeRepository) GetByID(ctx context.Context, id uuid.UUID) (*entit
 
 func (r *GamePrizeRepository) GetByGameID(ctx context.Context, gameID uuid.UUID) ([]entities.GamePrize, error) {
 	var gamePrizes []entities.GamePrize
-	err := r.db.WithContext(ctx).Preload("Game").Preload("FallbackPrize").Where("game_id = ?", gameID).Find(&gamePrizes).Error
+	err := DBFromContext(ctx, r.db).WithContext(ctx).Preload("Game").Preload("FallbackPrize").Where("game_id = ?", gameID).Find(&gamePrizes).Error
 	if err != nil {
 		return nil, err
 	}
@@ -43,7 +47,7 @@ func (r *GamePrizeRepository) List(ctx context.Context, offset, limit int, searc
 	var gamePrizes []entities.GamePrize
 	var total int64
 
-	query := r.db.WithContext(ctx).Preload("Game").Preload("FallbackPrize")
+	query := DBFromContext(ctx, r.db).WithContext(ctx).Preload("Game").Preload("FallbackPrize")
 
 	if search != "" {
 		searchTerm := "%" + search + "%"
@@ -76,22 +80,31 @@ func (r *GamePrizeRepository) List(ctx context.Context, offset, limit int, searc
 }
 
 func (r *GamePrizeRepository) Update(ctx context.Context, gamePrize *entities.GamePrize) error {
-	return r.db.WithContext(ctx).Save(gamePrize).Error
+	return DBFromContext(ctx, r.db).WithContext(ctx).Save(gamePrize).Error
 }
 
 func (r *GamePrizeRepository) Delete(ctx context.Context, id uuid.UUID) error {
-	return r.db.WithContext(ctx).Delete(&entities.GamePrize{}, id).Error
+	return DBFromContext(ctx, r.db).WithContext(ctx).Delete(&entities.GamePrize{}, id).Error
 }
 
+// DecreaseStock takes amount from a prize's stock. When less than amount is left it
+// changes nothing and returns ErrGamePrizeOutOfStock.
 func (r *GamePrizeRepository) DecreaseStock(ctx context.Context, id uuid.UUID, amount int) error {
-	return r.db.WithContext(ctx).Model(&entities.GamePrize{}).
+	res := DBFromContext(ctx, r.db).WithContext(ctx).Model(&entities.GamePrize{}).
 		Where("id = ? AND stock >= ?", id, amount).
-		Update("stock", gorm.Expr("stock - ?", amount)).Error
+		Update("stock", gorm.Expr("stock - ?", amount))
+	if res.Error != nil {
+		return fmt.Errorf("failed to decrease prize stock: %w", res.Error)
+	}
+	if res.RowsAffected == 0 {
+		return ErrGamePrizeOutOfStock
+	}
+	return nil
 }
 
 func (r *GamePrizeRepository) GetAvailablePrizes(ctx context.Context, gameID uuid.UUID) ([]entities.GamePrize, error) {
 	var gamePrizes []entities.GamePrize
-	err := r.db.WithContext(ctx).Preload("Game").Preload("FallbackPrize").
+	err := DBFromContext(ctx, r.db).WithContext(ctx).Preload("Game").Preload("FallbackPrize").
 		Where("game_id = ? AND stock > 0", gameID).
 		Order("weight DESC").
 		Find(&gamePrizes).Error