package main

import (
	"fmt"

	messages "git.tornberg.me/go-cart-actor/pkg/messages"
)

// mutation_set_cart_items.go
//
// Registers the SetCartRequest mutation. This mutation replaces the entire list
// of cart items with the provided list (each entry is an AddRequest).
//
// Behavior:
//   - Clears existing items (but leaves deliveries intact).
//   - Iterates over each AddRequest and delegates to CartGrain.AddItem
//     (which performs product lookup, creates AddItem mutation).
//   - If any single addition fails, the mutation aborts with an error;
//     items added prior to the failure remain (consistent with previous behavior).
//   - Totals recalculated after completion via WithTotals().
//
// Notes:
//   - Potential optimization: batch product lookups; currently sequential.
//   - Consider adding rollback semantics if atomic replacement is desired.
//   - Deliveries might reference item IDs that are now invalid—original logic
//     also left deliveries untouched. If that becomes an issue, add a cleanup
//     pass to remove deliveries whose item IDs no longer exist.
func init() {
	RegisterMutation[messages.SetCartRequest](
		"SetCartRequest",
		func(g *CartGrain, m *messages.SetCartRequest) error {
			if m == nil {
				return fmt.Errorf("SetCartRequest: nil payload")
			}

			// Clear current items (keep deliveries)
			g.mu.Lock()
			g.Items = make([]*CartItem, 0, len(m.Items))
			g.mu.Unlock()

			for _, it := range m.Items {
				if it == nil {
					continue
				}
				if it.Sku == "" || it.Quantity < 1 {
					return fmt.Errorf("SetCartRequest: invalid item (sku='%s' qty=%d)", it.Sku, it.Quantity)
				}
				_, err := g.AddItem(it.Sku, int(it.Quantity), it.Country, it.StoreId)
				if err != nil {
					return fmt.Errorf("SetCartRequest: add sku '%s' failed: %w", it.Sku, err)
				}
			}
			return nil
		},
		WithTotals(),
	)
}