package main

// mutation_add_request.go
//
// Registers the AddRequest mutation. This mutation is a higher-level intent
// (add by SKU + quantity) which may translate into either:
//   - Increasing quantity of an existing line (same SKU), OR
//   - Creating a new item by performing a product lookup (via getItemData inside CartGrain.AddItem)
//
// Behavior:
//   - Validates non-empty SKU and quantity > 0
//   - If an item with the SKU already exists: increments its quantity
//   - Else delegates to CartGrain.AddItem (which itself produces an AddItem mutation)
//   - Totals recalculated automatically (WithTotals)
//
// NOTE:
//   - This handler purposely avoids duplicating the detailed AddItem logic;
//     it reuses CartGrain.AddItem which then flows through the AddItem mutation
//     registry handler.
//   - Double total recalculation can occur (AddItem has WithTotals too), but
//     is acceptable for clarity. Optimize later if needed.
//
// Potential future improvements:
//   - Stock validation before increasing quantity
//   - Reservation logic or concurrency guards around stock updates
//   - Coupon / pricing rules applied conditionally during add-by-sku

// func HandleAddRequest(g *CartGrain, m *messages.AddRequest) error {
// 	if m == nil {
// 		return fmt.Errorf("AddRequest: nil payload")
// 	}
// 	if m.Sku == "" {
// 		return fmt.Errorf("AddRequest: sku is empty")
// 	}
// 	if m.Quantity < 1 {
// 		return fmt.Errorf("AddRequest: invalid quantity %d", m.Quantity)
// 	}

// 	// Existing line: accumulate quantity only.
// 	if existing, found := g.FindItemWithSku(m.Sku); found {
// 		existing.Quantity += int(m.Quantity)
// 		return nil
// 	}
// 	data, err := GetItemAddMessage(m.Sku, int(m.Quantity), m.Country, m.StoreId)
// 	if err != nil {
// 		return err
// 	}
// 	return AddItem(g, data)

// 	return err
// }