perf(analytics): optimize GetTrackStats to single query

veza-backend-api/internal/services/analytics_service.go

@@ -91,57 +91,45 @@ func (s *AnalyticsService) RecordPlay(ctx context.Context, trackID uuid.UUID, us
 	return nil
 }
 
-// GetTrackStats récupère les statistiques d'un track
-func (s *AnalyticsService) GetTrackStats(ctx context.Context, trackID uuid.UUID) (*types.TrackStats, error) { // Changed trackID to uuid.UUID
-	var stats types.TrackStats
-
-	// Vérifier que le track existe
-	var track models.Track
-	if err := s.db.WithContext(ctx).First(&track, "id = ?", trackID).Error; err != nil { // Updated query
-		if err == gorm.ErrRecordNotFound {
-			return nil, errors.New("track not found")
-		}
-		return nil, fmt.Errorf("failed to get track: %w", err)
+// GetTrackStats récupère les statistiques d'un track (optimisé: 1 requête au lieu de 5)
+func (s *AnalyticsService) GetTrackStats(ctx context.Context, trackID uuid.UUID) (*types.TrackStats, error) {
+	var result struct {
+		TrackDuration   int     `gorm:"column:track_duration"`
+		TotalPlays      int64   `gorm:"column:total_plays"`
+		UniqueListeners int64   `gorm:"column:unique_listeners"`
+		AvgDuration     float64 `gorm:"column:avg_duration"`
+		CompletedPlays  int64   `gorm:"column:completed_plays"`
 	}
 
-	// Total plays
-	if err := s.db.WithContext(ctx).Model(&models.TrackPlay{}).
-		Where("track_id = ?", trackID).
-		Count(&stats.TotalPlays).Error; err != nil {
-		return nil, fmt.Errorf("failed to count total plays: %w", err)
+	tx := s.db.WithContext(ctx).Raw(`
+		SELECT
+			t.duration AS track_duration,
+			CAST(COUNT(tp.id) AS INTEGER) AS total_plays,
+			CAST(COUNT(DISTINCT CASE WHEN tp.user_id IS NOT NULL THEN tp.user_id END) AS INTEGER) AS unique_listeners,
+			COALESCE(AVG(tp.duration), 0) AS avg_duration,
+			CAST(COUNT(CASE WHEN t.duration > 0 AND tp.duration >= t.duration * 0.9 THEN 1 END) AS INTEGER) AS completed_plays
+		FROM tracks t
+		LEFT JOIN track_plays tp ON tp.track_id = t.id
+		WHERE t.id = ?
+		GROUP BY t.id, t.duration
+	`, trackID).Scan(&result)
+	if tx.Error != nil {
+		return nil, fmt.Errorf("failed to get track stats: %w", tx.Error)
+	}
+	if tx.RowsAffected == 0 {
+		return nil, errors.New("track not found")
 	}
 
-	// Unique listeners (distinct user_id, en excluant NULL)
-	if err := s.db.WithContext(ctx).Model(&models.TrackPlay{}).
-		Where("track_id = ? AND user_id IS NOT NULL", trackID).
-		Distinct("user_id").
-		Count(&stats.UniqueListeners).Error; err != nil {
-		return nil, fmt.Errorf("failed to count unique listeners: %w", err)
+	stats := &types.TrackStats{
+		TotalPlays:       result.TotalPlays,
+		UniqueListeners:  result.UniqueListeners,
+		AverageDuration:  result.AvgDuration,
+		CompletionRate:   0,
 	}
-
-	// Average duration
-	var avgDuration float64
-	if err := s.db.WithContext(ctx).Model(&models.TrackPlay{}).
-		Where("track_id = ?", trackID).
-		Select("COALESCE(AVG(duration), 0)").
-		Scan(&avgDuration).Error; err != nil {
-		return nil, fmt.Errorf("failed to calculate average duration: %w", err)
+	if result.TotalPlays > 0 {
+		stats.CompletionRate = float64(result.CompletedPlays) / float64(result.TotalPlays) * 100
 	}
-	stats.AverageDuration = avgDuration
-
-	// Completion rate (90% de la durée du track)
-	if track.Duration > 0 && stats.TotalPlays > 0 {
-		var completedPlays int64
-		completionThreshold := int(float64(track.Duration) * 0.9)
-		if err := s.db.WithContext(ctx).Model(&models.TrackPlay{}).
-			Where("track_id = ? AND duration >= ?", trackID, completionThreshold).
-			Count(&completedPlays).Error; err != nil {
-			return nil, fmt.Errorf("failed to count completed plays: %w", err)
-		}
-		stats.CompletionRate = float64(completedPlays) / float64(stats.TotalPlays) * 100
-	}
-
-	return &stats, nil
+	return stats, nil
 }
 
 // GetPlaysOverTime récupère les lectures sur une période pour un graphique temporel