package pay

import (
	"context"
	"net/http"
	"strings"
	"testing"
	"time"
)

// --------------------------------------------------------------------------
// C2 · promo 限购 TOCTOU: CreateOrder's HasPaidPurchase check is a bare,
// unlocked SELECT at order-creation time — concurrent/multi-pending orders
// for the same promo SKU can both reach 'created' before either settles.
// webhook.go's settle must re-check inside the locked transaction, before
// granting, and swallow the duplicate (skip the grant, still ACK so pay
// doesn't retry forever) rather than double-granting +31 days per order.
// --------------------------------------------------------------------------

// seedPromoDuplicateOrders inserts two 'created' orders for the SAME user +
// promo SKU (pro_month_promo) — simulating the TOCTOU window where both
// orders were created before either was paid.
func seedPromoDuplicateOrders(t *testing.T, st *Store) {
	t.Helper()
	ctx := context.Background()
	if err := st.Insert(ctx, 1, "uuid-1", "pro_month_promo", "pay-promo-1", "alipay", 600, "CNY"); err != nil {
		t.Fatalf("insert promo order 1: %v", err)
	}
	if err := st.Insert(ctx, 1, "uuid-1", "pro_month_promo", "pay-promo-2", "wxpay", 600, "CNY"); err != nil {
		t.Fatalf("insert promo order 2: %v", err)
	}
}

func TestWebhook_PromoDuplicateSettleSkipsGrantButAcks(t *testing.T) {
	h, db, st := newWebhookRig(t)
	seedPromoDuplicateOrders(t, st)

	// First promo order settles normally: paid + granted.
	w1 := deliver(t, h, succeededPayload("pay-promo-1", "pro_month_promo"))
	if w1.Code != http.StatusOK || !strings.Contains(w1.Body.String(), "SUCCESS") {
		t.Fatalf("第一单应正常开通: %d %q", w1.Code, w1.Body.String())
	}
	var expiresAfterFirst time.Time
	if err := db.QueryRow(`SELECT expires_at FROM subscriptions WHERE user_id = 1`).Scan(&expiresAfterFirst); err != nil {
		t.Fatalf("第一单未开通订阅: %v", err)
	}

	// Second promo order for the SAME user+SKU settles (TOCTOU duplicate):
	// must still ACK 200 SUCCESS (else pay retries this webhook forever),
	// but must NOT grant a second +31 days.
	w2 := deliver(t, h, succeededPayload("pay-promo-2", "pro_month_promo"))
	if w2.Code != http.StatusOK || !strings.Contains(w2.Body.String(), "SUCCESS") {
		t.Fatalf("重复 promo 单应仍 ACK(否则 pay 会无限重投): %d %q", w2.Code, w2.Body.String())
	}

	var n int
	if err := db.QueryRow(`SELECT COUNT(*) FROM subscriptions WHERE user_id = 1`).Scan(&n); err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Fatalf("不得为重复 promo 单二次开通: subscriptions rows = %d, want 1", n)
	}
	var expiresAfterSecond time.Time
	if err := db.QueryRow(`SELECT expires_at FROM subscriptions WHERE user_id = 1`).Scan(&expiresAfterSecond); err != nil {
		t.Fatal(err)
	}
	if !expiresAfterFirst.Equal(expiresAfterSecond) {
		t.Errorf("到期被重复叠加: %v → %v(应保持不变,promo 限购一次)", expiresAfterFirst, expiresAfterSecond)
	}

	// The duplicate order's own ledger row must not become a second 'paid'
	// row for the same (user_id, sku) — that's exactly what migration 000027's
	// partial unique index forbids on sqlite, and what the settle-side
	// re-check must avoid ever attempting.
	row2, err := st.GetForUser(context.Background(), 1, "pay-promo-2")
	if err != nil {
		t.Fatalf("重复单台账未找到: %v", err)
	}
	if row2.Status == "paid" {
		t.Errorf("重复 promo 单不应被标记为二条 paid(会撞 (user_id,sku) 唯一索引): status = %q", row2.Status)
	}
	if row2.SubID.Valid {
		t.Errorf("重复 promo 单不应挂 sub_id: %+v", row2.SubID)
	}

	// Redelivery of the SAME duplicate webhook (new nonce, same out_trade_no)
	// must remain idempotent — no further side effects, still ACK.
	w3 := deliver(t, h, succeededPayload("pay-promo-2", "pro_month_promo"))
	if w3.Code != http.StatusOK || !strings.Contains(w3.Body.String(), "SUCCESS") {
		t.Fatalf("重复单再次重投应仍 ACK: %d %q", w3.Code, w3.Body.String())
	}
	if err := db.QueryRow(`SELECT COUNT(*) FROM subscriptions WHERE user_id = 1`).Scan(&n); err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Fatalf("重投重复单不得二次开通: subscriptions rows = %d, want 1", n)
	}
}

// --------------------------------------------------------------------------
// Defense-in-depth: migration 000027's sqlite partial unique index directly
// forbids two 'paid' rows for the same (user_id, sku='pro_month_promo'),
// independent of the application-layer settle check above. This guards
// against any other write path (bug, manual SQL, future code) accidentally
// double-marking a promo purchase 'paid'.
// --------------------------------------------------------------------------

func TestPayPurchases_PromoPaidUniqueIndex_SQLite(t *testing.T) {
	db := openMigratedSQLite(t)
	seedUser(t, db, 1, "uuid-1")
	now := time.Now().UTC()

	if _, err := db.Exec(
		`INSERT INTO pay_purchases (user_id, biz_ref, sku, out_trade_no, method, status, amount_minor, currency, created_at, updated_at)
		 VALUES (1, 'uuid-1', 'pro_month_promo', 'ux-1', 'alipay', 'paid', 600, 'CNY', ?, ?)`,
		now, now); err != nil {
		t.Fatalf("first paid promo row should insert cleanly: %v", err)
	}

	_, err := db.Exec(
		`INSERT INTO pay_purchases (user_id, biz_ref, sku, out_trade_no, method, status, amount_minor, currency, created_at, updated_at)
		 VALUES (1, 'uuid-1', 'pro_month_promo', 'ux-2', 'wxpay', 'paid', 600, 'CNY', ?, ?)`,
		now, now)
	if err == nil {
		t.Fatal("第二条同 user+promo-sku 的 paid 行应被部分唯一索引拒绝,却插入成功")
	}
	if !strings.Contains(err.Error(), "UNIQUE") {
		t.Errorf("err = %v, want a UNIQUE constraint violation", err)
	}

	// A non-promo SKU (or a 'created'/'canceled' status row) must be
	// unaffected by the partial index — sanity check it isn't over-broad.
	if _, err := db.Exec(
		`INSERT INTO pay_purchases (user_id, biz_ref, sku, out_trade_no, method, status, amount_minor, currency, created_at, updated_at)
		 VALUES (1, 'uuid-1', 'pro_month', 'ux-3', 'alipay', 'paid', 4990000, 'USDT', ?, ?)`,
		now, now); err != nil {
		t.Errorf("非 promo SKU 的 paid 行不应受此索引影响: %v", err)
	}

}