fix order and self order response

internal/repository/inventory_repository.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/google/uuid"
 	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
 )
 
 type InventoryRepository interface {
@@ -278,7 +279,12 @@ func (r *InventoryRepositoryImpl) UpdateReorderLevel(ctx context.Context, id uui
 }
 
 func (r *InventoryRepositoryImpl) BulkCreate(ctx context.Context, inventoryItems []*entities.Inventory) error {
-	return r.db.WithContext(ctx).CreateInBatches(inventoryItems, 100).Error
+	return r.db.WithContext(ctx).
+		Clauses(clause.OnConflict{
+			Columns:   []clause.Column{{Name: "outlet_id"}, {Name: "product_id"}},
+			DoNothing: true,
+		}).
+		CreateInBatches(inventoryItems, 100).Error
 }
 
 func (r *InventoryRepositoryImpl) BulkUpdate(ctx context.Context, inventoryItems []*entities.Inventory) error {
@@ -301,21 +307,25 @@ func (r *InventoryRepositoryImpl) BulkAdjustQuantity(ctx context.Context, adjust
 	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
 		for productID, delta := range adjustments {
 			var inventory entities.Inventory
-			if err := tx.Where("product_id = ? AND outlet_id = ?", productID, outletID).First(&inventory).Error; err != nil {
-				if errors.Is(err, gorm.ErrRecordNotFound) {
-					// Inventory doesn't exist, create it with initial quantity
-					inventory = entities.Inventory{
-						ProductID:    productID,
-						OutletID:     outletID,
-						Quantity:     0,
-						ReorderLevel: 0,
-					}
-					if err := tx.Create(&inventory).Error; err != nil {
-						return fmt.Errorf("failed to create inventory record for product %s: %w", productID, err)
-					}
-				} else {
+			err := tx.Set("gorm:query_option", "FOR UPDATE").
+				Where("product_id = ? AND outlet_id = ?", productID, outletID).
+				First(&inventory).Error
+			if err != nil {
+				if !errors.Is(err, gorm.ErrRecordNotFound) {
 					return err
 				}
+				// Use FirstOrCreate to handle race conditions — avoids duplicate key
+				// if another transaction already inserted this row concurrently.
+				inventory = entities.Inventory{
+					ProductID:    productID,
+					OutletID:     outletID,
+					Quantity:     0,
+					ReorderLevel: 0,
+				}
+				if err := tx.Where(entities.Inventory{ProductID: productID, OutletID: outletID}).
+					FirstOrCreate(&inventory).Error; err != nil {
+					return fmt.Errorf("failed to create inventory record for product %s: %w", productID, err)
+				}
 			}
 
 			inventory.UpdateQuantity(delta)