package main

import (
	"strconv"
	"testing"

	"git.k6n.net/mats/platform/catalog"
	"git.k6n.net/mats/platform/money"
)

// frameMeta builds the event.Meta a producer stamps for a snapshot frame / delta.
func frameMeta(phase string, epoch int64) map[string]string {
	m := map[string]string{catalog.MetaEpoch: strconv.FormatInt(epoch, 10), catalog.MetaTenant: "se"}
	if phase != "" {
		m[catalog.MetaSnapshotPhase] = phase
	}
	return m
}

func enc(t *testing.T, ups []catalog.ProjectionUpdate) []byte {
	t.Helper()
	b, err := catalog.EncodeUpdates(ups)
	if err != nil {
		t.Fatalf("encode: %v", err)
	}
	return b
}

// TestCartCache_SnapshotThenDelta exercises the cart's cache through the real bus
// framing: a full begin→chunk→end snapshot makes SKUs Get-able cold (no Apply),
// then an epoch-matched delta overrides one and tombstones another.
func TestCartCache_SnapshotThenDelta(t *testing.T) {
	c := mustCache(t)

	const epoch = int64(1000)
	if err := c.HandleFrame(frameMeta(catalog.SnapshotBegin, epoch), enc(t, nil)); err != nil {
		t.Fatal(err)
	}
	if err := c.HandleFrame(frameMeta(catalog.SnapshotChunk, epoch), enc(t, []catalog.ProjectionUpdate{
		{Projection: catalog.Projection{ID: "sku:A", SKU: "A", PriceIncVat: money.Cents(100_00), TaxClass: "standard", ItemID: 1}},
		{Projection: catalog.Projection{ID: "sku:B", SKU: "B", PriceIncVat: money.Cents(50_00), TaxClass: "reduced", ItemID: 2}},
	})); err != nil {
		t.Fatal(err)
	}
	// end carries the total count for the completeness guard.
	endMeta := frameMeta(catalog.SnapshotEnd, epoch)
	endMeta[catalog.MetaCount] = "2"
	if err := c.HandleFrame(endMeta, enc(t, nil)); err != nil {
		t.Fatal(err)
	}

	if got, ok := c.Get("A"); !ok || got.PriceIncVat != 100_00 {
		t.Fatalf("A from snapshot = %+v ok=%v, want 10000", got, ok)
	}

	// Epoch-matched delta: bump A's price, delete B.
	if err := c.HandleFrame(frameMeta("", epoch), enc(t, []catalog.ProjectionUpdate{
		{Projection: catalog.Projection{SKU: "A", PriceIncVat: money.Cents(90_00), TaxClass: "standard", ItemID: 1}},
		{Projection: catalog.Projection{SKU: "B"}, Deleted: true},
	})); err != nil {
		t.Fatal(err)
	}
	if got, _ := c.Get("A"); got.PriceIncVat != 90_00 {
		t.Fatalf("A after delta = %d, want 9000", got.PriceIncVat)
	}
	if _, ok := c.Get("B"); ok {
		t.Fatalf("B after delete should miss")
	}
	if !c.IsDeleted("B") {
		t.Fatalf("B should be tombstoned (skip HTTP fetch)")
	}
}