//go:build integration

package ai

import (
	"errors"
	"fmt"
	"os"
	"sync"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
	"senlinai-agent/backend/internal/models"
)

func TestPostgresReserveRateLimitIsAtomicAcrossConcurrentConnections(t *testing.T) {
	dsn := os.Getenv("TEST_DATABASE_URL")
	require.NotEmpty(t, dsn, "TEST_DATABASE_URL is required for integration tests and must point to an isolated database")
	database, err := gorm.Open(postgres.Open(dsn), &gorm.Config{TranslateError: true, Logger: logger.Default.LogMode(logger.Silent)})
	require.NoError(t, err)
	require.NoError(t, models.AutoMigrate(database))
	models.DBService = database
	suffix := fmt.Sprint(time.Now().UnixNano())
	user := createAIRateTestUser(t, database, "postgres-rate-"+suffix+"@example.com")
	action := "postgres_concurrent_" + suffix
	t.Cleanup(func() {
		database.Where("user_id = ?", user.ID).Delete(&models.SaAIRateBucket{})
		database.Delete(&user)
	})
	gateway := NewGatewayWithSecret("system-key", "test-encryption-secret")
	const (
		limit    = 9
		attempts = 48
	)

	start := make(chan struct{})
	results := make(chan error, attempts)
	var wait sync.WaitGroup
	for range attempts {
		wait.Add(1)
		go func() {
			defer wait.Done()
			<-start
			results <- gateway.ReserveRateLimit(user.ID, action, limit, time.Hour)
		}()
	}
	close(start)
	wait.Wait()
	close(results)

	allowed := 0
	limited := 0
	for err := range results {
		switch {
		case err == nil:
			allowed++
		case errors.Is(err, ErrAIRateLimited):
			limited++
		default:
			require.NoError(t, err)
		}
	}
	require.Equal(t, limit, allowed)
	require.Equal(t, attempts-limit, limited)
	var bucket models.SaAIRateBucket
	require.NoError(t, database.Where("user_id = ? AND action = ?", user.ID, action).First(&bucket).Error)
	require.Equal(t, limit, bucket.Count)
}