package cart

import (
	"context"
	"testing"
	"time"

	"git.k6n.net/go-cart-actor/pkg/actor"
	cart_messages "git.k6n.net/go-cart-actor/proto/cart"
	"google.golang.org/protobuf/proto"
)

// Removing a parent line cascades to its child sub-articles, while unrelated
// lines are left untouched.
func TestRemoveItem_CascadesToChildren(t *testing.T) {
	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
	g := NewCartGrain(1, time.Now())
	ctx := context.Background()

	// Parent (line 1) + two children (lines 2,3) + an unrelated item (line 4).
	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 100, Sku: "P", Quantity: 1, Price: 1000})
	parentLine := g.Items[0].Id
	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 101, Sku: "C1", Quantity: 1, Price: 100, ParentId: &parentLine})
	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 102, Sku: "C2", Quantity: 1, Price: 200, ParentId: &parentLine})
	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 200, Sku: "OTHER", Quantity: 1, Price: 300})

	if len(g.Items) != 4 {
		t.Fatalf("setup: items = %d, want 4", len(g.Items))
	}

	if _, err := reg.Apply(ctx, g, &cart_messages.RemoveItem{Id: parentLine}); err != nil {
		t.Fatalf("remove parent: %v", err)
	}

	if len(g.Items) != 1 {
		t.Fatalf("after remove: items = %d, want 1 (only the unrelated line)", len(g.Items))
	}
	if g.Items[0].Sku != "OTHER" {
		t.Errorf("remaining item sku = %q, want OTHER", g.Items[0].Sku)
	}
}

// Removing a child leaves the parent and siblings intact.
func TestRemoveItem_ChildDoesNotRemoveParent(t *testing.T) {
	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
	g := NewCartGrain(1, time.Now())
	ctx := context.Background()

	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 100, Sku: "P", Quantity: 1, Price: 1000})
	parentLine := g.Items[0].Id
	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 101, Sku: "C1", Quantity: 1, Price: 100, ParentId: &parentLine})
	childLine := g.Items[1].Id

	if _, err := reg.Apply(ctx, g, &cart_messages.RemoveItem{Id: childLine}); err != nil {
		t.Fatalf("remove child: %v", err)
	}
	if len(g.Items) != 1 {
		t.Fatalf("items = %d, want 1 (parent remains)", len(g.Items))
	}
	if g.Items[0].Id != parentLine {
		t.Errorf("remaining line = %d, want parent %d", g.Items[0].Id, parentLine)
	}
}

func mustApply(t *testing.T, reg actor.MutationRegistry, g *CartGrain, m proto.Message) {
	t.Helper()
	if _, err := reg.Apply(context.Background(), g, m); err != nil {
		t.Fatalf("apply %T: %v", m, err)
	}
}