package workers

import (
	"context"
	"fmt"
	"time"

	"veza-backend-api/internal/email"
	"veza-backend-api/internal/services"

	"github.com/google/uuid"
	"go.uber.org/zap"
	"gorm.io/gorm"
)

// JobWorker gère les tâches en arrière-plan
type JobWorker struct {
	db                *gorm.DB
	jobService        *services.JobService
	logger            *zap.Logger
	queue             chan Job
	maxRetries        int
	processingWorkers int
	emailSender       email.EmailSender // Email sender pour les jobs d'email
}

// Job représente une tâche à traiter
type Job struct {
	ID        uuid.UUID
	Type      string
	Payload   map[string]interface{}
	Retries   int
	CreatedAt time.Time
	Priority  int // 1 = haut, 2 = moyen, 3 = bas
}

// NewJobWorker crée un nouveau worker de jobs
func NewJobWorker(
	db *gorm.DB,
	jobService *services.JobService,
	logger *zap.Logger,
	queueSize int,
	workers int,
	maxRetries int,
	emailSender email.EmailSender,
) *JobWorker {
	return &JobWorker{
		db:                db,
		jobService:        jobService,
		logger:            logger,
		queue:             make(chan Job, queueSize),
		maxRetries:        maxRetries,
		processingWorkers: workers,
		emailSender:       emailSender,
	}
}

// Enqueue ajoute un job au queue
func (w *JobWorker) Enqueue(job Job) {
	job.CreatedAt = time.Now()
	if job.ID == uuid.Nil {
		job.ID = uuid.New()
	}

	select {
	case w.queue <- job:
		w.logger.Debug("Job enqueued",
			zap.String("job_id", job.ID.String()),
			zap.String("job_type", job.Type),
			zap.Int("priority", job.Priority))
	default:
		w.logger.Warn("Job queue full, dropping job",
			zap.String("job_type", job.Type))
	}
}

// Start démarre le worker
func (w *JobWorker) Start(ctx context.Context) {
	w.logger.Info("Starting job worker",
		zap.Int("workers", w.processingWorkers))

	for i := 0; i < w.processingWorkers; i++ {
		go w.processWorker(ctx, i)
	}
}

// processWorker traite les jobs du queue
func (w *JobWorker) processWorker(ctx context.Context, workerID int) {
	w.logger.Info("Job worker started",
		zap.Int("worker_id", workerID))

	for {
		select {
		case <-ctx.Done():
			w.logger.Info("Job worker stopping",
				zap.Int("worker_id", workerID))
			return

		case job := <-w.queue:
			w.processJob(ctx, job, workerID)
		}
	}
}

// processJob traite un job individuel
func (w *JobWorker) processJob(ctx context.Context, job Job, workerID int) {
	logger := w.logger.With(
		zap.String("job_id", job.ID.String()),
		zap.String("job_type", job.Type),
		zap.Int("worker_id", workerID))

	logger.Info("Processing job",
		zap.Int("retries", job.Retries))

	// Créer un contexte avec timeout
	jobCtx, cancel := context.WithTimeout(ctx, 5*time.Minute)
	defer cancel()

	// Traiter le job selon son type
	err := w.executeJob(jobCtx, job)

	if err != nil {
		logger.Error("Job execution failed",
			zap.Error(err))

		// Retry si pas atteint max retries
		if job.Retries < w.maxRetries {
			job.Retries++

			// Exponential backoff
			delay := time.Duration(job.Retries) * 5 * time.Second
			
			// Non-blocking retry: re-enqueue after delay
			go func(d time.Duration, j Job) {
				time.Sleep(d)
				w.Enqueue(j)
			}(delay, job)

			logger.Info("Job scheduled for retry",
				zap.Duration("delay", delay),
				zap.Int("new_retries", job.Retries))
		} else {
			logger.Error("Job failed after max retries",
				zap.Int("max_retries", w.maxRetries))

			// Enregistrer l'échec définitif
			w.logFailedJob(ctx, job, err)
		}
	} else {
		logger.Info("Job executed successfully")
	}
}

// executeJob exécute un job selon son type
func (w *JobWorker) executeJob(ctx context.Context, job Job) error {
	switch job.Type {
	case "email":
		return w.processEmailJob(ctx, job)
	case "thumbnail":
		return w.processThumbnailJob(ctx, job)
	case "analytics":
		return w.processAnalyticsJob(ctx, job)
	default:
		return fmt.Errorf("unknown job type: %s", job.Type)
	}
}

// processEmailJob traite un job d'email
func (w *JobWorker) processEmailJob(ctx context.Context, job Job) error {
	// Extraire les données du payload
	to, ok := job.Payload["to"].(string)
	if !ok {
		return fmt.Errorf("missing 'to' in payload")
	}

	subject, _ := job.Payload["subject"].(string)
	body, _ := job.Payload["body"].(string)
	templateName, _ := job.Payload["template"].(string)
	
	// Extraire les données du template si présentes
	var templateData map[string]interface{}
	if data, ok := job.Payload["template_data"].(map[string]interface{}); ok {
		templateData = data
	} else {
		templateData = make(map[string]interface{})
	}

	// Créer l'EmailJob
	var emailJob *EmailJob
	if templateName != "" {
		emailJob = NewEmailJobWithTemplate(to, subject, templateName, templateData)
	} else {
		emailJob = NewEmailJob(to, subject, body)
	}

	// Exécuter le job d'email
	if err := emailJob.Execute(ctx, w.emailSender, w.logger); err != nil {
		return fmt.Errorf("email job execution failed: %w", err)
	}

	return nil
}

// EnqueueEmailJob ajoute un job d'email au queue (méthode helper)
func (w *JobWorker) EnqueueEmailJob(to, subject, body string) {
	job := Job{
		Type:     "email",
		Priority: 2, // Priorité moyenne par défaut
		Payload: map[string]interface{}{
			"to":      to,
			"subject": subject,
			"body":    body,
		},
	}
	w.Enqueue(job)
}

// EnqueueEmailJobWithTemplate ajoute un job d'email avec template au queue
func (w *JobWorker) EnqueueEmailJobWithTemplate(to, subject, templateName string, templateData map[string]interface{}) {
	job := Job{
		Type:     "email",
		Priority: 2, // Priorité moyenne par défaut
		Payload: map[string]interface{}{
			"to":           to,
			"subject":      subject,
			"template":     templateName,
			"template_data": templateData,
		},
	}
	w.Enqueue(job)
}

// EnqueueThumbnailJob ajoute un job de génération de thumbnail au queue
func (w *JobWorker) EnqueueThumbnailJob(inputPath, outputPath string, width, height int) {
	job := Job{
		Type:     "thumbnail",
		Priority: 2, // Priorité moyenne par défaut
		Payload: map[string]interface{}{
			"input_path":  inputPath,
			"output_path": outputPath,
			"width":       float64(width),
			"height":      float64(height),
		},
	}
	w.Enqueue(job)
}

// EnqueueAnalyticsJob ajoute un job d'analytics au queue
func (w *JobWorker) EnqueueAnalyticsJob(eventName string, userID *uuid.UUID, payload map[string]interface{}) {
	jobPayload := map[string]interface{}{
		"event_name": eventName,
		"payload":     payload,
	}
	if userID != nil {
		jobPayload["user_id"] = userID.String()
	}

	job := Job{
		Type:     "analytics",
		Priority: 3, // Priorité basse par défaut (analytics non critique)
		Payload:   jobPayload,
	}
	w.Enqueue(job)
}

// processThumbnailJob traite un job de génération de thumbnail
func (w *JobWorker) processThumbnailJob(ctx context.Context, job Job) error {
	// Extraire les paramètres du payload
	inputPath, ok := job.Payload["input_path"].(string)
	if !ok {
		return fmt.Errorf("missing 'input_path' in payload")
	}

	outputPath, ok := job.Payload["output_path"].(string)
	if !ok {
		return fmt.Errorf("missing 'output_path' in payload")
	}

	// Largeur et hauteur (optionnels, avec valeurs par défaut)
	width := 300
	height := 300
	if w, ok := job.Payload["width"].(float64); ok {
		width = int(w)
	}
	if h, ok := job.Payload["height"].(float64); ok {
		height = int(h)
	}

	// Créer et exécuter le ThumbnailJob
	thumbnailJob := NewThumbnailJob(inputPath, outputPath, width, height)
	if err := thumbnailJob.Execute(ctx, w.logger); err != nil {
		return fmt.Errorf("thumbnail job execution failed: %w", err)
	}

	return nil
}

// processAnalyticsJob traite un job d'analytics
func (w *JobWorker) processAnalyticsJob(ctx context.Context, job Job) error {
	// Extraire les données du payload
	eventName, ok := job.Payload["event_name"].(string)
	if !ok {
		return fmt.Errorf("missing 'event_name' in payload")
	}

	// UserID (optionnel, peut être nil pour événements anonymes)
	var userID *uuid.UUID
	if uidStr, ok := job.Payload["user_id"].(string); ok && uidStr != "" {
		uid, err := uuid.Parse(uidStr)
		if err != nil {
			return fmt.Errorf("invalid user_id format: %w", err)
		}
		userID = &uid
	}

	// Payload additionnel (optionnel)
	var payload map[string]interface{}
	if p, ok := job.Payload["payload"].(map[string]interface{}); ok {
		payload = p
	} else {
		payload = make(map[string]interface{})
	}

	// Créer et exécuter l'AnalyticsEventJob
	analyticsJob := NewAnalyticsEventJob(eventName, userID, payload)
	if err := analyticsJob.Execute(ctx, w.db, w.logger); err != nil {
		return fmt.Errorf("analytics job execution failed: %w", err)
	}

	return nil
}

// logFailedJob enregistre un échec de job
func (w *JobWorker) logFailedJob(ctx context.Context, job Job, err error) {
	// TODO: Enregistrer dans la table job_failures
	w.logger.Error("Job permanently failed",
		zap.String("job_id", job.ID.String()),
		zap.String("job_type", job.Type),
		zap.Error(err))
}

// GetStats retourne les statistiques du worker
func (w *JobWorker) GetStats() map[string]interface{} {
	return map[string]interface{}{
		"queue_size":  len(w.queue),
		"workers":     w.processingWorkers,
		"max_retries": w.maxRetries,
	}
}