package lottery

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"testing"

	"github.com/DATA-DOG/go-sqlmock"
	"gorm.io/driver/mysql"
	"gorm.io/gorm"
)

func newLotteryTestDB(t *testing.T) (*gorm.DB, sqlmock.Sqlmock, func()) {
	t.Helper()
	sqlDB, mock, err := sqlmock.New(sqlmock.QueryMatcherOption(sqlmock.QueryMatcherFunc(func(expected, actual string) error {
		if strings.Contains(actual, expected) {
			return nil
		}
		return fmt.Errorf("actual sql %q does not contain %q", actual, expected)
	})))
	if err != nil {
		t.Fatalf("create sqlmock: %v", err)
	}
	db, err := gorm.Open(mysql.New(mysql.Config{Conn: sqlDB, SkipInitializeWithVersion: true}), &gorm.Config{})
	if err != nil {
		_ = sqlDB.Close()
		t.Fatalf("open gorm db: %v", err)
	}
	return db, mock, func() { _ = sqlDB.Close() }
}

func TestChanceService_Grant_ZeroAmountShortCircuits(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	svc := NewChanceService(db)
	if err := svc.Grant(context.Background(), 1, 100, "manual_grant", "ref-1", 0); err != nil {
		t.Fatalf("Grant(amount=0) unexpected err: %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("no queries expected, got: %v", err)
	}
}

func TestChanceService_Grant_FirstTimeInsertsGrantAndBalance(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	mock.ExpectBegin()
	// INSERT lottery_chance_grant，未冲突返回 1 行
	mock.ExpectExec("INSERT INTO `lottery_chance_grant`").
		WillReturnResult(sqlmock.NewResult(1, 1))
	// UPSERT lottery_chance_balance
	mock.ExpectExec("INSERT INTO `lottery_chance_balance`").
		WillReturnResult(sqlmock.NewResult(1, 1))
	mock.ExpectCommit()

	svc := NewChanceService(db)
	if err := svc.Grant(context.Background(), 42, 100, "invite_success", "order-xyz", 3); err != nil {
		t.Fatalf("Grant: %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("expectations: %v", err)
	}
}

func TestChanceService_Grant_IdempotentOnDuplicateSourceRef(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	mock.ExpectBegin()
	// INSERT lottery_chance_grant，UNIQUE 冲突 → 0 行影响
	mock.ExpectExec("INSERT INTO `lottery_chance_grant`").
		WillReturnResult(sqlmock.NewResult(0, 0))
	// balance 不应被触发
	mock.ExpectCommit()

	svc := NewChanceService(db)
	if err := svc.Grant(context.Background(), 42, 100, "invite_success", "order-xyz", 3); err != nil {
		t.Fatalf("Grant: %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("expectations: %v", err)
	}
}

func TestChanceService_Consume_LocksAndDecrements(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	mock.ExpectBegin()
	mock.ExpectQuery("FROM `lottery_chance_balance`").
		WithArgs(int64(42), int64(100), 1).
		WillReturnRows(sqlmock.NewRows([]string{"id", "user_id", "activity_id", "remaining", "total_earned", "total_spent"}).
			AddRow(int64(9), int64(42), int64(100), int64(2), int64(3), int64(1)))
	mock.ExpectExec("UPDATE `lottery_chance_balance`").
		WithArgs(sqlmock.AnyArg(), int64(9)).
		WillReturnResult(sqlmock.NewResult(0, 1))
	mock.ExpectCommit()

	svc := NewChanceService(db)
	var remaining int64
	err := db.Transaction(func(tx *gorm.DB) error {
		var e error
		remaining, e = svc.Consume(context.Background(), tx, 42, 100)
		return e
	})
	if err != nil {
		t.Fatalf("Consume: %v", err)
	}
	if remaining != 1 {
		t.Fatalf("expected remaining=1, got %d", remaining)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("expectations: %v", err)
	}
}

func TestChanceService_Consume_NoRowReturnsErrNoChances(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	mock.ExpectBegin()
	mock.ExpectQuery("FROM `lottery_chance_balance`").
		WithArgs(int64(42), int64(100), 1).
		WillReturnError(gorm.ErrRecordNotFound)
	mock.ExpectRollback()

	svc := NewChanceService(db)
	err := db.Transaction(func(tx *gorm.DB) error {
		_, e := svc.Consume(context.Background(), tx, 42, 100)
		return e
	})
	if !errors.Is(err, ErrNoChances) {
		t.Fatalf("expected ErrNoChances, got %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("expectations: %v", err)
	}
}

func TestChanceService_Consume_ZeroRemainingReturnsErrNoChances(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	mock.ExpectBegin()
	mock.ExpectQuery("FROM `lottery_chance_balance`").
		WithArgs(int64(42), int64(100), 1).
		WillReturnRows(sqlmock.NewRows([]string{"id", "user_id", "activity_id", "remaining", "total_earned", "total_spent"}).
			AddRow(int64(9), int64(42), int64(100), int64(0), int64(3), int64(3)))
	mock.ExpectRollback()

	svc := NewChanceService(db)
	err := db.Transaction(func(tx *gorm.DB) error {
		_, e := svc.Consume(context.Background(), tx, 42, 100)
		return e
	})
	if !errors.Is(err, ErrNoChances) {
		t.Fatalf("expected ErrNoChances when remaining=0, got %v", err)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("expectations: %v", err)
	}
}

func TestChanceService_Consume_RequiresTx(t *testing.T) {
	db, _, cleanup := newLotteryTestDB(t)
	defer cleanup()

	svc := NewChanceService(db)
	if _, err := svc.Consume(context.Background(), nil, 1, 1); err == nil {
		t.Fatalf("expected error when tx is nil")
	}
}

func TestChanceService_Query_NotFoundReturnsZero(t *testing.T) {
	db, mock, cleanup := newLotteryTestDB(t)
	defer cleanup()

	mock.ExpectQuery("FROM `lottery_chance_balance`").
		WithArgs(int64(42), int64(100), 1).
		WillReturnError(gorm.ErrRecordNotFound)

	svc := NewChanceService(db)
	got, err := svc.Query(context.Background(), 42, 100)
	if err != nil {
		t.Fatalf("Query: %v", err)
	}
	if got != 0 {
		t.Fatalf("expected 0 when no row, got %d", got)
	}
	if err := mock.ExpectationsWereMet(); err != nil {
		t.Fatalf("expectations: %v", err)
	}
}