feat(lyrics): show songwriter and provider credits after lyrics

lib/l10n/arb/app_en.arb

@@ -6282,6 +6282,10 @@
   },
   "nowPlayingUpNext": "Up next",
   "nowPlayingAudioOutput": "Audio Output",
+  "nowPlayingWrittenBy": "Written by: {writers}",
+  "@nowPlayingWrittenBy": {"placeholders": {"writers": {"type": "String"}}},
+  "nowPlayingLyricsProvider": "Lyrics: {provider}",
+  "@nowPlayingLyricsProvider": {"placeholders": {"provider": {"type": "String"}}},
   "concertGetTickets": "Get Tickets",
   "concertSetList": "Concert Set List",
   "concertSetListButton": "Set List",

lib/l10n/arb/app_id.arb

@@ -4578,6 +4578,8 @@
   },
   "nowPlayingUpNext": "Up next",
   "nowPlayingAudioOutput": "Output Audio",
+  "nowPlayingWrittenBy": "Ditulis oleh: {writers}",
+  "nowPlayingLyricsProvider": "Lirik: {provider}",
   "concertGetTickets": "Beli Tiket",
   "concertSetList": "Set List Konser",
   "concertSetListButton": "Set List",

lib/screens/now_playing_screen.dart

@@ -1693,6 +1693,7 @@ class _NowPlayingScreenState extends ConsumerState<NowPlayingScreen> {
         children: [
           _SyncedLyricsView(
             lyrics: _lyrics,
+            credits: _lyricsCredits(),
             colorScheme: colorScheme,
             isActive: isActive,
             showPronunciation: visibility.$1,
@@ -1709,17 +1710,36 @@ class _NowPlayingScreenState extends ConsumerState<NowPlayingScreen> {
     }
     return SingleChildScrollView(
       padding: const EdgeInsets.fromLTRB(24, 16, 24, 32),
-      child: Text(
-        _lyrics.plainText,
-        style: Theme.of(context).textTheme.titleMedium?.copyWith(
-          height: 1.6,
-          color: colorScheme.onSurface,
-        ),
-        textAlign: TextAlign.center,
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: [
+          Text(
+            _lyrics.plainText,
+            style: Theme.of(context).textTheme.titleMedium?.copyWith(
+              height: 1.6,
+              color: colorScheme.onSurface,
+            ),
+            textAlign: TextAlign.center,
+          ),
+          ?_lyricsCredits(),
+        ],
       ),
     );
   }
 
+  _LyricsCredits? _lyricsCredits() {
+    String? metadata(String key) {
+      final value = _metadata?[key];
+      return value is String && value.trim().isNotEmpty ? value.trim() : null;
+    }
+
+    final writers =
+        _lyrics.writers ?? metadata('lyricist') ?? metadata('composer');
+    final provider = _lyrics.provider ?? metadata('lyrics_provider');
+    if (writers == null && provider == null) return null;
+    return _LyricsCredits(writers: writers, provider: provider);
+  }
+
   Widget? _lyricsOptionsButton(ColorScheme colorScheme) {
     if (_loadingMeta || !_lyrics.synced) return null;
     final pronunciation = _lyrics.lines.any(
@@ -2680,6 +2700,7 @@ class _PlaybackControls extends ConsumerWidget {
 
 class _SyncedLyricsView extends ConsumerStatefulWidget {
   final ParsedLyrics lyrics;
+  final _LyricsCredits? credits;
   final ColorScheme colorScheme;
   final bool isActive;
   final bool showPronunciation;
@@ -2687,6 +2708,7 @@ class _SyncedLyricsView extends ConsumerStatefulWidget {
 
   const _SyncedLyricsView({
     required this.lyrics,
+    this.credits,
     required this.colorScheme,
     required this.isActive,
     required this.showPronunciation,
@@ -3065,11 +3087,17 @@ class _SyncedLyricsViewState extends ConsumerState<_SyncedLyricsView> {
           return ListView.builder(
             controller: _scroll,
             itemExtentBuilder: mornye
-                ? (index, _) => _lineExtents![index]
+                ? (index, _) => index < lines.length
+                      ? _lineExtents![index]
+                      : widget.credits!.heightFor(
+                          context,
+                          constraints.maxWidth - 48,
+                        )
                 : null,
             padding: EdgeInsets.fromLTRB(24, centerPadding, 24, bottomPadding),
-            itemCount: lines.length,
+            itemCount: lines.length + (widget.credits == null ? 0 : 1),
             itemBuilder: (context, index) {
+              if (index == lines.length) return widget.credits!;
               final line = lines[index];
               final isActive = index == active;
               final isPast = index < active;
@@ -3191,6 +3219,43 @@ class _SyncedLyricsViewState extends ConsumerState<_SyncedLyricsView> {
   }
 }
 
+class _LyricsCredits extends StatelessWidget {
+  const _LyricsCredits({this.writers, this.provider});
+
+  final String? writers;
+  final String? provider;
+
+  String _text(BuildContext context) => [
+    if (writers != null) context.l10n.nowPlayingWrittenBy(writers!),
+    if (provider != null) context.l10n.nowPlayingLyricsProvider(provider!),
+  ].join('\n');
+
+  TextStyle _style(BuildContext context) =>
+      Theme.of(context).textTheme.bodyMedium!.copyWith(
+        fontSize: context.isMornye ? 17 : 14,
+        fontWeight: FontWeight.w600,
+        height: 1.4,
+        color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.48),
+      );
+
+  double heightFor(BuildContext context, double width) {
+    final painter = TextPainter(
+      text: TextSpan(text: _text(context), style: _style(context)),
+      textDirection: Directionality.of(context),
+      textScaler: MediaQuery.textScalerOf(context),
+    )..layout(maxWidth: width.clamp(0, double.infinity));
+    final height = painter.height + 32;
+    painter.dispose();
+    return height;
+  }
+
+  @override
+  Widget build(BuildContext context) => Padding(
+    padding: const EdgeInsets.symmetric(vertical: 16),
+    child: Text(_text(context), style: _style(context)),
+  );
+}
+
 Iterable<(String, TextStyle, List<LyricWord>, bool)> _lyricSupplements(
   BuildContext context,
   LyricLine line,

lib/utils/lyrics_parser.dart

@@ -37,12 +37,16 @@ class ParsedLyrics {
   final bool wordSynced;
   final List<LyricLine> lines;
   final String plainText;
+  final String? writers;
+  final String? provider;
 
   const ParsedLyrics({
     required this.synced,
     required this.wordSynced,
     required this.lines,
     required this.plainText,
+    this.writers,
+    this.provider,
   });
 
   bool get isEmpty => lines.isEmpty && plainText.trim().isEmpty;
@@ -84,10 +88,71 @@ class LyricsParser {
 
     if (_looksLikeTtml(text)) {
       final ttml = _parseTtml(text);
-      if (ttml != null && ttml.lines.isNotEmpty) return ttml;
+      if (ttml != null && ttml.lines.isNotEmpty) {
+        return _withCredits(text, ttml);
+      }
     }
 
-    return _parseLrcOrPlain(text);
+    return _withCredits(text, _parseLrcOrPlain(text));
+  }
+
+  static ParsedLyrics _withCredits(String raw, ParsedLyrics lyrics) {
+    String? tag(String name) => RegExp(
+      '^\\[$name:([^\\]\\r\\n]*)\\]\\s*\$',
+      multiLine: true,
+      caseSensitive: false,
+    ).firstMatch(raw)?.group(1)?.trim();
+    var writers = tag('au');
+    var provider = tag('x-provider');
+    final credit = tag('by') ?? '';
+    provider ??= RegExp(r'\bvia\s+([^\(]+)', caseSensitive: false)
+        .firstMatch(credit)
+        ?.group(1)
+        ?.trim()
+        .replaceFirst(RegExp(r'\s+API$', caseSensitive: false), '');
+    provider ??= RegExp(
+      r'\(source:\s*([^\)]+)\)',
+      caseSensitive: false,
+    ).firstMatch(credit)?.group(1)?.trim();
+    provider = provider?.replaceFirst(
+      RegExp(r'^extension:', caseSensitive: false),
+      '',
+    );
+    if (_looksLikeTtml(raw)) {
+      try {
+        final doc = XmlDocument.parse(raw);
+        final names = doc.descendants
+            .whereType<XmlElement>()
+            .where((node) => node.name.local == 'songwriter')
+            .map((node) => node.innerText.trim())
+            .where((name) => name.isNotEmpty)
+            .toSet();
+        if (names.isNotEmpty) writers = names.join(', ');
+      } on XmlParserException {
+        // Malformed optional credits must not prevent lyric playback.
+      }
+    }
+    var lines = lyrics.lines;
+    if (lines.isNotEmpty) {
+      final trailer = RegExp(
+        r'^Written\s+by\s*:\s*(.+)$',
+        caseSensitive: false,
+      ).firstMatch(lines.last.text.trim());
+      if (trailer != null) {
+        writers ??= trailer.group(1)?.trim();
+        lines = lines.sublist(0, lines.length - 1);
+      }
+    }
+    return ParsedLyrics(
+      synced: lyrics.synced,
+      wordSynced: lyrics.wordSynced,
+      lines: lines,
+      plainText: identical(lines, lyrics.lines)
+          ? lyrics.plainText
+          : lines.map((line) => line.text).join('\n'),
+      writers: writers?.isNotEmpty == true ? writers : null,
+      provider: provider?.isNotEmpty == true ? provider : null,
+    );
   }
 
   static bool _looksLikeTtml(String text) {