minstrel/flutter_client/lib/playlists/playlist_detail_screen.dart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../cache/audio_cache_manager.dart';
import '../cache/db.dart';
import '../models/playlist.dart';
import '../models/track.dart';
import '../player/player_provider.dart';
import '../shared/live_events_provider.dart';
import '../shared/widgets/track_actions/track_actions_button.dart';
import '../theme/theme_extension.dart';
import 'playlists_provider.dart';

class PlaylistDetailScreen extends ConsumerWidget {
  const PlaylistDetailScreen({required this.id, this.seed, super.key});
  final String id;

  /// Optional Playlist passed via go_router extra so the header
  /// (title, cover, track count, play/download CTAs) can render
  /// before the full detail fetch resolves. Same pattern as album
  /// + artist nav hydration.
  final Playlist? seed;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
    // #402 wire-up: invalidate the detail provider on playlist.updated /
    // .tracks_changed events whose payload matches the visible id. On
    // .deleted matching this id, navigate back so the user isn't left
    // staring at a gone-from-server playlist.
    ref.listen<AsyncValue<LiveEvent>>(liveEventsProvider, (_, next) {
      final e = next.asData?.value;
      if (e == null) return;
      final eventPlaylistId = e.data['playlist_id'] as String?;
      if (eventPlaylistId != id) return;
      switch (e.kind) {
        case 'playlist.updated':
        case 'playlist.tracks_changed':
          ref.invalidate(playlistDetailProvider(id));
        case 'playlist.deleted':
          if (context.mounted) context.pop();
      }
    });
    final detail = ref.watch(playlistDetailProvider(id));

    // Resolve the best playlist info available for the AppBar title.
    final livePlaylist = detail.value?.playlist;
    final headerName = (livePlaylist != null && livePlaylist.name.isNotEmpty)
        ? livePlaylist.name
        : (seed?.name ?? '');

    return Scaffold(
      backgroundColor: fs.obsidian,
      appBar: AppBar(
        backgroundColor: fs.obsidian,
        elevation: 0,
        leading: IconButton(
          icon: Icon(Icons.arrow_back, color: fs.parchment),
          onPressed: () => context.pop(),
        ),
        title: headerName.isEmpty
            ? const SizedBox.shrink()
            : Text(
                headerName,
                style: TextStyle(color: fs.parchment),
                overflow: TextOverflow.ellipsis,
              ),
      ),
      body: detail.when(
        // Loading from a seed: render the header immediately + a
        // small inline "loading tracks" hint, instead of an opaque
        // full-screen spinner. The body fills in when tracks arrive.
        loading: () => seed == null
            ? const Center(child: CircularProgressIndicator())
            : _SeedBody(playlist: seed!),
        error: (e, _) =>
            Center(child: Text('$e', style: TextStyle(color: fs.error))),
        data: (d) => _Body(detail: d),
      ),
    );
  }
}

/// Loading-state body: renders just the header from the seed
/// playlist + a "loading tracks…" placeholder. CTA buttons are
/// hidden until the real track list arrives (they need playable
/// refs to do anything useful).
class _SeedBody extends StatelessWidget {
  const _SeedBody({required this.playlist});
  final Playlist playlist;

  @override
  Widget build(BuildContext context) {
    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
    return ListView(children: [
      Padding(
        padding: const EdgeInsets.fromLTRB(16, 8, 16, 16),
        child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
          if (playlist.description.isNotEmpty)
            Padding(
              padding: const EdgeInsets.only(bottom: 12),
              child: Text(
                playlist.description,
                style: TextStyle(color: fs.ash, fontSize: 13),
              ),
            ),
          Text(
            '${playlist.trackCount} ${playlist.trackCount == 1 ? "track" : "tracks"}',
            style: TextStyle(color: fs.ash, fontSize: 12),
          ),
        ]),
      ),
      const Padding(
        padding: EdgeInsets.symmetric(vertical: 24),
        child: Center(child: CircularProgressIndicator()),
      ),
    ]);
  }
}

class _Body extends ConsumerWidget {
  const _Body({required this.detail});
  final PlaylistDetail detail;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
    final tracks = detail.tracks;
    final playable = tracks.where((t) => t.isAvailable).toList();

    return RefreshIndicator(
      onRefresh: () async =>
          ref.refresh(playlistDetailProvider(detail.playlist.id).future),
      child: ListView.builder(
        // Header + (track rows | empty hint).
        itemCount: tracks.isEmpty ? 2 : tracks.length + 1,
        itemBuilder: (ctx, i) {
          if (i == 0) return _Header(detail: detail, playable: playable);
          if (tracks.isEmpty) {
            return Padding(
              padding: const EdgeInsets.all(24),
              child: Center(
                child: Text(
                  'No tracks yet. Add some via the "Add to playlist…" entry on any track row.',
                  style: TextStyle(color: fs.ash),
                  textAlign: TextAlign.center,
                ),
              ),
            );
          }
          final t = tracks[i - 1];
          return _PlaylistTrackRow(
            row: t,
            onTap: t.isAvailable
                ? () {
                    final ref = ProviderScope.containerOf(ctx);
                    final liveTrack = _toTrackRef(t);
                    final playableRefs =
                        playable.map(_toTrackRef).toList(growable: false);
                    final startIdx = playable.indexWhere((p) => p.trackId == t.trackId);
                    ref.read(playerActionsProvider).playTracks(
                          playableRefs,
                          initialIndex: startIdx >= 0 ? startIdx : 0,
                        );
                    // Keep liveTrack referenced to avoid an unused-variable
                    // warning while we leave hooks for menu wiring later.
                    assert(liveTrack.id == t.trackId);
                  }
                : null,
          );
        },
      ),
    );
  }
}

TrackRef _toTrackRef(PlaylistTrack t) => TrackRef(
      id: t.trackId ?? '',
      title: t.title,
      albumId: t.albumId ?? '',
      albumTitle: t.albumTitle,
      artistId: t.artistId ?? '',
      artistName: t.artistName,
      durationSec: t.durationSec,
      streamUrl: t.streamUrl ?? '',
    );

class _Header extends ConsumerWidget {
  const _Header({required this.detail, required this.playable});
  final PlaylistDetail detail;
  final List<PlaylistTrack> playable;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
    final p = detail.playlist;
    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 8, 16, 16),
      child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
        if (p.description.isNotEmpty)
          Padding(
            padding: const EdgeInsets.only(bottom: 12),
            child: Text(
              p.description,
              style: TextStyle(color: fs.ash, fontSize: 13),
            ),
          ),
        Row(children: [
          Text(
            '${p.trackCount} ${p.trackCount == 1 ? "track" : "tracks"}',
            style: TextStyle(color: fs.ash, fontSize: 12),
          ),
          const Spacer(),
          if (playable.isNotEmpty) ...[
            OutlinedButton.icon(
              key: const Key('download_playlist_button'),
              onPressed: () {
                final mgr = ref.read(audioCacheManagerProvider);
                for (final t in playable) {
                  final id = t.trackId ?? '';
                  if (id.isEmpty) continue;
                  // Fire-and-forget; downloads happen in background.
                  // ignore: unawaited_futures
                  mgr.pin(id, source: CacheSource.autoPlaylist);
                }
                ScaffoldMessenger.of(context).showSnackBar(
                  SnackBar(content: Text('Downloading ${playable.length} tracks…')),
                );
              },
              icon: const Icon(Icons.download, size: 16),
              label: const Text('Download'),
            ),
            const SizedBox(width: 8),
            FilledButton.icon(
              onPressed: () {
                final refs = playable.map(_toTrackRef).toList(growable: false);
                ref.read(playerActionsProvider).playTracks(refs);
              },
              icon: const Icon(Icons.play_arrow),
              label: const Text('Play'),
              style: FilledButton.styleFrom(
                backgroundColor: fs.accent,
                foregroundColor: fs.parchment,
              ),
            ),
          ],
        ]),
      ]),
    );
  }
}

class _PlaylistTrackRow extends ConsumerWidget {
  const _PlaylistTrackRow({required this.row, required this.onTap});
  final PlaylistTrack row;
  final VoidCallback? onTap;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
    final mins = (row.durationSec ~/ 60).toString().padLeft(2, '0');
    final secs = (row.durationSec % 60).toString().padLeft(2, '0');
    // "Now playing" highlight — matches _QueueRow and TrackRow so the
    // user sees which playlist row is current without reading the
    // player bar. Unavailable rows never match.
    final currentId = ref.watch(mediaItemProvider).value?.id;
    final isCurrent = row.isAvailable &&
        currentId != null &&
        currentId == row.trackId;
    final baseColor = row.isAvailable ? fs.parchment : fs.ash;
    final titleColor = isCurrent ? fs.accent : baseColor;
    return Container(
      decoration: BoxDecoration(
        color: isCurrent ? fs.iron : null,
        border: isCurrent
            ? Border(left: BorderSide(color: fs.accent, width: 2))
            : null,
      ),
      child: InkWell(
        onTap: onTap,
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
          child: Row(children: [
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    row.title,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: TextStyle(
                      color: titleColor,
                      fontSize: 14,
                      fontWeight:
                          isCurrent ? FontWeight.w500 : FontWeight.w400,
                      decoration: row.isAvailable
                          ? null
                          : TextDecoration.lineThrough,
                    ),
                  ),
                  Text(
                    '${row.artistName} · ${row.albumTitle}',
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: TextStyle(color: fs.ash, fontSize: 12),
                  ),
                ],
              ),
            ),
            Text('$mins:$secs', style: TextStyle(color: fs.ash, fontSize: 12)),
            if (row.trackId != null)
              TrackActionsButton(track: _toTrackRef(row)),
          ]),
        ),
      ),
    );
  }
}