refactor: simplify & deduplicate

lib/utils/plex_cache_parser.dart

@@ -0,0 +1,57 @@
+/// Utility class for parsing Plex API cache responses
+///
+/// Provides consistent extraction of MediaContainer data across the codebase.
+class PlexCacheParser {
+  PlexCacheParser._();
+
+  /// Extract the Metadata list from a cached response
+  ///
+  /// Returns null if MediaContainer or Metadata is not present
+  static List<dynamic>? extractMetadataList(Map<String, dynamic>? cached) {
+    if (cached == null) return null;
+    return cached['MediaContainer']?['Metadata'] as List?;
+  }
+
+  /// Extract the first metadata item from a cached response
+  ///
+  /// Returns null if no metadata exists
+  static Map<String, dynamic>? extractFirstMetadata(
+    Map<String, dynamic>? cached,
+  ) {
+    final list = extractMetadataList(cached);
+    if (list == null || list.isEmpty) return null;
+    return list[0] as Map<String, dynamic>;
+  }
+
+  /// Check if a cached response has valid metadata
+  static bool hasMetadata(Map<String, dynamic>? cached) {
+    final list = extractMetadataList(cached);
+    return list != null && list.isNotEmpty;
+  }
+
+  /// Extract Directory list from a cached response (for libraries, playlists)
+  static List<dynamic>? extractDirectoryList(Map<String, dynamic>? cached) {
+    if (cached == null) return null;
+    return cached['MediaContainer']?['Directory'] as List?;
+  }
+
+  /// Extract Hub list from a cached response
+  static List<dynamic>? extractHubList(Map<String, dynamic>? cached) {
+    if (cached == null) return null;
+    return cached['MediaContainer']?['Hub'] as List?;
+  }
+
+  /// Extract Chapter list from the first metadata item
+  static List<dynamic>? extractChapters(Map<String, dynamic>? cached) {
+    final metadata = extractFirstMetadata(cached);
+    if (metadata == null) return null;
+    return metadata['Chapter'] as List?;
+  }
+
+  /// Extract Marker list from the first metadata item
+  static List<dynamic>? extractMarkers(Map<String, dynamic>? cached) {
+    final metadata = extractFirstMetadata(cached);
+    if (metadata == null) return null;
+    return metadata['Marker'] as List?;
+  }
+}