package workers

import (
	"context"
	"fmt"
	"time"

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

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

// WebhookWorker gère les webhooks en arrière-plan
type WebhookWorker struct {
	db                *gorm.DB
	webhookService    *services.WebhookService
	logger            *zap.Logger
	queue             chan WebhookJob
	maxRetries        int
	processingWorkers int
}

// WebhookJob représente une tâche de webhook à traiter
type WebhookJob struct {
	ID        uuid.UUID
	Webhook   *models.Webhook
	Event     string
	Data      map[string]interface{}
	Retries   int
	CreatedAt time.Time
}

// NewWebhookWorker crée un nouveau worker de webhooks
func NewWebhookWorker(
	db *gorm.DB,
	webhookService *services.WebhookService,
	logger *zap.Logger,
	queueSize int,
	workers int,
	maxRetries int,
) *WebhookWorker {
	return &WebhookWorker{
		db:                db,
		webhookService:    webhookService,
		logger:            logger,
		queue:             make(chan WebhookJob, queueSize),
		maxRetries:        maxRetries,
		processingWorkers: workers,
	}
}

// Enqueue ajoute un job au queue
func (w *WebhookWorker) Enqueue(job WebhookJob) {
	job.CreatedAt = time.Now()
	job.ID = uuid.New()

	select {
	case w.queue <- job:
		w.logger.Debug("Webhook job enqueued",
			zap.String("job_id", job.ID.String()),
			zap.String("event", job.Event),
			zap.String("webhook_url", job.Webhook.URL))
	default:
		w.logger.Warn("Webhook queue full, dropping job",
			zap.String("event", job.Event))
	}
}

// Start démarre le worker
func (w *WebhookWorker) Start(ctx context.Context) {
	w.logger.Info("Starting webhook 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 *WebhookWorker) processWorker(ctx context.Context, workerID int) {
	w.logger.Info("Webhook worker started",
		zap.Int("worker_id", workerID))

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

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

// processJob traite un job individuel
func (w *WebhookWorker) processJob(ctx context.Context, job WebhookJob, workerID int) {
	logger := w.logger.With(
		zap.String("job_id", job.ID.String()),
		zap.String("event", job.Event),
		zap.Int("worker_id", workerID))

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

	// Créer un contexte avec timeout pour la livraison
	deliveryCtx, cancel := context.WithTimeout(ctx, 30*time.Second)
	defer cancel()

	// Tenter de livrer le webhook
	err := w.webhookService.DeliverWebhook(
		deliveryCtx,
		job.Webhook,
		job.Event,
		job.Data,
	)

	if err != nil {
		logger.Error("Webhook delivery failed",
			zap.Error(err))

		// Enregistrer l'échec dans la table de logs
		w.logFailedDelivery(ctx, job, err)

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

			// Exponential backoff via time.AfterFunc (non-blocking)
			delay := time.Duration(job.Retries) * time.Second
			
			time.AfterFunc(delay, func() {
				// Ré-enqueue le job
				w.Enqueue(job)
				logger.Info("Retrying webhook delivery (enqueued)",
					zap.Int("new_retries", job.Retries))
			})
		} else {
			logger.Error("Webhook delivery failed after max retries",
				zap.Int("max_retries", w.maxRetries))
		}
	} else {
		logger.Info("Webhook delivered successfully")
	}
}

// logFailedDelivery enregistre un échec de livraison
func (w *WebhookWorker) logFailedDelivery(ctx context.Context, job WebhookJob, err error) {
	failure := &models.WebhookFailure{
		WebhookID: job.Webhook.ID,
		Event:     job.Event,
		Error:     err.Error(),
		Retries:   job.Retries,
		CreatedAt: time.Now(),
	}

	if err := w.db.WithContext(ctx).Create(failure).Error; err != nil {
		w.logger.Error("Failed to log webhook failure",
			zap.Error(err),
			zap.String("job_id", job.ID.String()))
	}
}

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

// CleanupOldFailures supprime les anciennes pannes de livraison
func (w *WebhookWorker) CleanupOldFailures(ctx context.Context, daysOld int) error {
	cutoffDate := time.Now().AddDate(0, 0, -daysOld)

	result := w.db.WithContext(ctx).
		Where("created_at < ?", cutoffDate).
		Delete(&models.WebhookFailure{})

	if result.Error != nil {
		return fmt.Errorf("failed to cleanup old failures: %w", result.Error)
	}

	w.logger.Info("Cleaned up old webhook failures",
		zap.Int("rows_deleted", int(result.RowsAffected)),
		zap.Int("days_old", daysOld))

	return nil
}

// RequeueFailed retente les webhooks en échec
func (w *WebhookWorker) RequeueFailed(ctx context.Context, failure *models.WebhookFailure) error {
	// Récupérer le webhook
	var webhook models.Webhook
	if err := w.db.WithContext(ctx).
		First(&webhook, failure.WebhookID).Error; err != nil {
		return fmt.Errorf("failed to fetch webhook: %w", err)
	}

	// Enqueue à nouveau
	job := WebhookJob{
		Webhook: &webhook,
		Event:   failure.Event,
		Data:    map[string]interface{}{}, // On perd les données originales
		Retries: failure.Retries,
	}

	w.Enqueue(job)

	w.logger.Info("Requeued failed webhook",
		zap.String("webhook_id", failure.WebhookID.String()),
		zap.Int("retries", failure.Retries))

	return nil
}