package repository

import (
	"context"
	"database/sql"
	"errors"
	"testing"
)

// mockQueryer implements sqlQueryer for testing
type mockQueryer struct {
	rows *sql.Rows
	err  error
}

func (m *mockQueryer) QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) {
	return m.rows, m.err
}

func TestScanSingleRow_QueryError(t *testing.T) {
	ctx := context.Background()
	mockErr := errors.New("query failed")
	q := &mockQueryer{err: mockErr}

	var dest int
	err := scanSingleRow(ctx, q, "SELECT 1", nil, &dest)
	if err == nil {
		t.Fatal("expected error, got nil")
	}
	if !errors.Is(err, mockErr) {
		t.Errorf("expected query error, got %v", err)
	}
}

func TestScanSingleRow_NoRows(t *testing.T) {
	// This test requires a real database connection to create sql.Rows.
	// scanSingleRow is designed to work with any sqlQueryer, but creating
	// a mock sql.Rows without a real driver is complex.
	// We test the behavior through integration with the test database.
	db := openTestDB(t)
	ctx := context.Background()

	// Use the raw sql.DB from gorm
	sqlDB, err := db.DB()
	if err != nil {
		t.Fatalf("get sql.DB failed: %v", err)
	}

	var dest int
	err = scanSingleRow(ctx, sqlDB, "SELECT 1 WHERE 1=0", nil, &dest)
	if err == nil {
		t.Fatal("expected error for no rows, got nil")
	}
	if !errors.Is(err, sql.ErrNoRows) {
		t.Errorf("expected sql.ErrNoRows, got %v", err)
	}
}

func TestScanSingleRow_Success(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()

	sqlDB, err := db.DB()
	if err != nil {
		t.Fatalf("get sql.DB failed: %v", err)
	}

	var dest int
	err = scanSingleRow(ctx, sqlDB, "SELECT 42", nil, &dest)
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if dest != 42 {
		t.Errorf("expected 42, got %d", dest)
	}
}

func TestScanSingleRow_MultipleColumns(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()

	sqlDB, err := db.DB()
	if err != nil {
		t.Fatalf("get sql.DB failed: %v", err)
	}

	var a, b int
	err = scanSingleRow(ctx, sqlDB, "SELECT 1, 2", nil, &a, &b)
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if a != 1 {
		t.Errorf("expected a=1, got %d", a)
	}
	if b != 2 {
		t.Errorf("expected b=2, got %d", b)
	}
}

func TestScanSingleRow_StringResult(t *testing.T) {
	db := openTestDB(t)
	ctx := context.Background()

	sqlDB, err := db.DB()
	if err != nil {
		t.Fatalf("get sql.DB failed: %v", err)
	}

	var dest string
	err = scanSingleRow(ctx, sqlDB, "SELECT 'hello'", nil, &dest)
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if dest != "hello" {
		t.Errorf("expected 'hello', got %q", dest)
	}
}