package main

import (
	"testing"

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

// TestProjectionCache_ApplyUpserts covers the happy path: a batch of N
// projections reaches the cache via Apply, all are visible via Get.
func TestProjectionCache_ApplyUpserts(t *testing.T) {
	c := newCatalogProjectionCache()
	updates := []catalog.ProjectionUpdate{
		{Projection: catalog.Projection{ID: "id-A", SKU: "A", PriceIncVat: money.Cents(100_00), TaxClass: "standard"}},
		{Projection: catalog.Projection{ID: "id-B", SKU: "B", PriceIncVat: money.Cents(150_00), TaxClass: "reduced"}},
		{Projection: catalog.Projection{ID: "id-C", SKU: "C", PriceIncVat: money.Cents(0), TaxClass: ""}},
	}
	upserts, deletes := c.Apply(updates)
	if upserts != 3 || deletes != 0 {
		t.Fatalf("counts: upserts=%d deletes=%d, want 3/0", upserts, deletes)
	}
	for _, want := range []struct {
		sku    string
		price  money.Cents
		taxCls string
	}{
		{"A", money.Cents(100_00), "standard"},
		{"B", money.Cents(150_00), "reduced"},
		{"C", money.Cents(0), ""},
	} {
		got, ok := c.Get(want.sku)
		if !ok {
			t.Fatalf("Get(%q): missing", want.sku)
		}
		if got.PriceIncVat != want.price || got.TaxClass != want.taxCls {
			t.Fatalf("Get(%q) = %+v, want price=%d taxCls=%q", want.sku, got, want.price, want.taxCls)
		}
	}
	if c.Len() != 3 {
		t.Fatalf("Len = %d, want 3", c.Len())
	}
}

// TestProjectionCache_DeleteTombstone verifies that a delete update sets a
// tombstone (not removes the entry), so:
//   - Get returns (_, false) on a deleted SKU
//   - IsDeleted returns true
//   - the same entry continues to count toward Len (size accounting)
func TestProjectionCache_DeleteTombstone(t *testing.T) {
	c := newCatalogProjectionCache()
	c.Apply([]catalog.ProjectionUpdate{
		{Projection: catalog.Projection{ID: "id-A", SKU: "A", PriceIncVat: money.Cents(100_00)}},
	})
	if _, ok := c.Get("A"); !ok {
		t.Fatalf("A: expected hit before delete")
	}

	upserts, deletes := c.Apply([]catalog.ProjectionUpdate{
		{Projection: catalog.Projection{SKU: "A"}, Deleted: true},
	})
	if upserts != 0 || deletes != 1 {
		t.Fatalf("delete counts: upserts=%d deletes=%d, want 0/1", upserts, deletes)
	}

	if got, ok := c.Get("A"); ok {
		t.Fatalf("A after delete: got %+v ok=true, want miss", got)
	}
	if !c.IsDeleted("A") {
		t.Fatalf("A after delete: IsDeleted false")
	}
	if c.IsDeleted("UNKNOWN") {
		t.Fatalf("UNKNOWN: IsDeleted should be false (entry doesn't exist)")
	}
	if c.Len() != 1 {
		t.Fatalf("Len after tombstone: %d, want 1 (tombstone still in map)", c.Len())
	}
}

// TestProjectionCache_BusResurrect verifies that a fresh upsert after a delete
// clears the tombstone (live entry replaces it): Get returns the projection,
// IsDeleted flips to false. Mirrors how the live catalog keeps flipping state.
func TestProjectionCache_BusResurrect(t *testing.T) {
	c := newCatalogProjectionCache()
	c.Apply([]catalog.ProjectionUpdate{
		{Projection: catalog.Projection{SKU: "A", PriceIncVat: money.Cents(50_00)}},
		{Projection: catalog.Projection{SKU: "A"}, Deleted: true},
	})
	if !c.IsDeleted("A") {
		t.Fatalf("A: not tombstoned after delete")
	}

	c.Apply([]catalog.ProjectionUpdate{
		{Projection: catalog.Projection{SKU: "A", PriceIncVat: money.Cents(75_00)}},
	})

	got, ok := c.Get("A")
	if !ok {
		t.Fatalf("A: expected live after re-upsert")
	}
	if got.PriceIncVat != money.Cents(75_00) {
		t.Fatalf("A re-upsert price = %d, want 7500", got.PriceIncVat)
	}
	if c.IsDeleted("A") {
		t.Fatalf("A: still tombstoned after re-upsert")
	}
}

// TestProjectionCache_EmptySKUIgnored validates that an upsert with an empty
// SKU is a no-op (defensive — bus should never publish "" but cheaper to log
// + drop than to populate an ambiguous cache slot).
func TestProjectionCache_EmptySKUIgnored(t *testing.T) {
	c := newCatalogProjectionCache()
	upserts, _ := c.Apply([]catalog.ProjectionUpdate{
		{Projection: catalog.Projection{SKU: "", PriceIncVat: money.Cents(100_00)}},
	})
	if upserts != 0 {
		t.Fatalf("empty-SKU upsert: %d, want 0", upserts)
	}
	if c.Len() != 0 {
		t.Fatalf("Len after empty-SKU: %d, want 0", c.Len())
	}
}

// TestProjectionCache_BusRaceSafe runs Apply + Get concurrently under -race
// to lock down the lock order. Run via `go test -race ./cmd/cart/...`.
func TestProjectionCache_BusRaceSafe(t *testing.T) {
	c := newCatalogProjectionCache()
	done := make(chan struct{})
	go func() {
		defer close(done)
		for i := 0; i < 500; i++ {
			c.Apply([]catalog.ProjectionUpdate{
				{Projection: catalog.Projection{SKU: "X", PriceIncVat: money.Cents(int64(i * 100))}},
			})
		}
	}()
	for i := 0; i < 2000; i++ {
		_, _ = c.Get("X")
		_ = c.IsDeleted("X")
		_ = c.Len()
	}
	<-done
	if _, ok := c.Get("X"); !ok {
		t.Fatalf("final Get(X): miss after concurrent writes")
	}
}

// TestTaxResolveBp covers the static TaxClass→bp mapping used by
// ApplyProjectionOverlay. Adds a regression net for the common Nordic rates.
func TestTaxResolveBp(t *testing.T) {
	cases := []struct {
		class string
		want  int
	}{
		{"standard", 2500},
		{"reduced", 1200},
		{"lowered", 600},
		{"zero", 0},
		{"exempt", 0},
		{"", 2500}, // missing class defaults to standard (matches mutation registry)
		{"unknown-class", 2500},
	}
	for _, tc := range cases {
		got := resolveTaxBp(tc.class)
		if got != tc.want {
			t.Errorf("resolveTaxBp(%q) = %d, want %d", tc.class, got, tc.want)
		}
	}
}