package cart

import (
	"context"
	"testing"
	"time"

	cart_messages "git.k6n.net/mats/go-cart-actor/proto/cart"
)

// Item identity is the catalog item id, not the (reference-only) SKU: two adds
// with the same ItemId but different SKU strings must merge into one line.
func TestAddItem_MergesByItemIdNotSku(t *testing.T) {
	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
	g := NewCartGrain(1, time.Now())
	ctx := context.Background()

	if _, err := reg.Apply(ctx, g, &cart_messages.AddItem{ItemId: 144047, Sku: "A0162590", Quantity: 1, Price: 1000}); err != nil {
		t.Fatalf("first add: %v", err)
	}
	// Same id, different (reference) sku string -> should merge, not create a line.
	if _, err := reg.Apply(ctx, g, &cart_messages.AddItem{ItemId: 144047, Sku: "STALE-REF", Quantity: 2, Price: 1000}); err != nil {
		t.Fatalf("second add: %v", err)
	}

	if len(g.Items) != 1 {
		t.Fatalf("items = %d, want 1 (merged by id)", len(g.Items))
	}
	if g.Items[0].Quantity != 3 {
		t.Errorf("quantity = %d, want 3", g.Items[0].Quantity)
	}

	// A different id is a distinct line.
	if _, err := reg.Apply(ctx, g, &cart_messages.AddItem{ItemId: 170852, Sku: "A0190103", Quantity: 1, Price: 500}); err != nil {
		t.Fatalf("third add: %v", err)
	}
	if len(g.Items) != 2 {
		t.Fatalf("items = %d, want 2", len(g.Items))
	}
}

// Re-adding the same parent (same ItemId + StoreId, no ParentId on the
// re-add itself) merges the quantity, and the proportional cascade resizes
// every direct child to match the new parent qty so a "+1 drill" leaves
// the bundle internally consistent.
func TestAddItem_MergeCascadesToChildren(t *testing.T) {
	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
	g := NewCartGrain(1, time.Now())
	ctx := context.Background()

	if _, err := reg.Apply(ctx, g, &cart_messages.AddItem{ItemId: 100, Sku: "P", Quantity: 1, Price: 1000}); err != nil {
		t.Fatalf("add parent: %v", err)
	}
	parentLine := g.Items[0].Id
	if _, err := reg.Apply(ctx, g, &cart_messages.AddItem{ItemId: 101, Sku: "C1", Quantity: 1, Price: 100, ParentId: &parentLine}); err != nil {
		t.Fatalf("add child: %v", err)
	}

	// Re-add the same parent — same ItemId, no ParentId on the re-add itself.
	if _, err := reg.Apply(ctx, g, &cart_messages.AddItem{ItemId: 100, Sku: "P", Quantity: 1, Price: 1000}); err != nil {
		t.Fatalf("re-add parent: %v", err)
	}

	// Parent qty 1 -> 2; child qty 1 -> 2 via cascade.
	for _, it := range g.Items {
		if it.Quantity != 2 {
			t.Errorf("line %s qty = %d, want 2 (merge cascade)", it.Sku, it.Quantity)
		}
	}
}