Initial commit - SoundWave v1.0

- Full PWA support with offline capabilities
- Comprehensive search across songs, playlists, and channels
- Offline playlist manager with download tracking
- Pre-built frontend for zero-build deployment
- Docker-based deployment with docker compose
- Material-UI dark theme interface
- YouTube audio download and management
- Multi-user authentication support

backend/playlist/serializers.py

@@ -0,0 +1,59 @@
+"""Playlist serializers"""
+
+from rest_framework import serializers
+from playlist.models import Playlist, PlaylistItem
+import re
+
+
+class PlaylistSubscribeSerializer(serializers.Serializer):
+    """Playlist subscription from URL"""
+    url = serializers.URLField(required=True, help_text="YouTube playlist URL")
+
+    def validate_url(self, value):
+        """Extract playlist ID from URL"""
+        # Match YouTube playlist URL patterns
+        patterns = [
+            r'[?&]list=([a-zA-Z0-9_-]+)',
+            r'playlist\?list=([a-zA-Z0-9_-]+)',
+        ]
+        
+        for pattern in patterns:
+            match = re.search(pattern, value)
+            if match:
+                return match.group(1)
+        
+        # If it's just a playlist ID
+        if len(value) >= 13 and value.startswith(('PL', 'UU', 'LL', 'RD')):
+            return value
+            
+        raise serializers.ValidationError("Invalid YouTube playlist URL")
+
+
+class PlaylistSerializer(serializers.ModelSerializer):
+    """Playlist serializer"""
+    item_count = serializers.SerializerMethodField()
+    progress_percent = serializers.SerializerMethodField()
+    status_display = serializers.CharField(source='get_sync_status_display', read_only=True)
+
+    class Meta:
+        model = Playlist
+        fields = '__all__'
+        read_only_fields = ['owner', 'created_date', 'last_updated', 'last_refresh']
+
+    def get_item_count(self, obj):
+        return obj.items.count()
+    
+    def get_progress_percent(self, obj):
+        """Calculate download progress percentage"""
+        if obj.item_count == 0:
+            return 0
+        return int((obj.downloaded_count / obj.item_count) * 100)
+
+
+class PlaylistItemSerializer(serializers.ModelSerializer):
+    """Playlist item serializer"""
+
+    class Meta:
+        model = PlaylistItem
+        fields = '__all__'
+        read_only_fields = ['added_date']