import 'dart:io';

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

import '../api/endpoints/likes.dart' show LikeKind;
import '../likes/like_button.dart';
import '../models/track.dart';
import '../shared/widgets/server_image.dart';
import '../shared/widgets/track_actions/track_actions_button.dart';
import '../theme/theme_extension.dart';
import 'album_color_extractor.dart';
import 'player_provider.dart';

/// Hero tag shared between the mini player's cover and the full-screen
/// _AlbumArt's cover so tapping the mini bar animates the artwork from
/// the bar's footprint to the full-screen size. Stable per-route (not
/// keyed by media.id) so the transition works regardless of what's
/// playing.
const String kPlayerCoverHeroTag = 'player-cover';

/// Duration for the AnimatedSwitcher / AnimatedContainer track-change
/// crossfade. ~300ms reads as a smooth transition without dragging.
const Duration _trackChangeDuration = Duration(milliseconds: 300);

/// Full-screen player. Mounted on /now-playing. Pushed via a slide-up
/// transition (see routing.dart). Dismisses three ways:
///
/// - System back / leading button → Navigator.pop
/// - Vertical drag down past threshold → Navigator.pop (matches the
///   slide-down animation users expect from a "pull down to close"
///   sheet)
/// - Tap of the mini player ascends here; reverse motion descends back.
class NowPlayingScreen extends ConsumerStatefulWidget {
  const NowPlayingScreen({super.key});

  @override
  ConsumerState<NowPlayingScreen> createState() => _NowPlayingScreenState();
}

class _NowPlayingScreenState extends ConsumerState<NowPlayingScreen> {
  // Cumulative drag distance used to decide if a vertical drag should
  // dismiss. Reset on each drag start.
  double _dragOffset = 0;

  void _onDragStart(DragStartDetails _) {
    _dragOffset = 0;
  }

  void _onDragUpdate(DragUpdateDetails d) {
    _dragOffset += d.delta.dy;
  }

  void _onDragEnd(DragEndDetails d) {
    // Pop when either the user has dragged > 80px down OR flicked
    // downward at speed (>500 px/s). Either should feel responsive
    // without dismissing on accidental drags.
    final flicked = d.primaryVelocity != null && d.primaryVelocity! > 500;
    if (_dragOffset > 80 || flicked) {
      Navigator.of(context).maybePop();
    }
    _dragOffset = 0;
  }

  @override
  Widget build(BuildContext context) {
    final fs = Theme.of(context).extension<FabledSwordTheme>()!;
    final media = ref.watch(mediaItemProvider).value;
    final playback = ref.watch(playbackStateProvider).value;

    if (media == null) {
      return const Scaffold(body: Center(child: Text('Nothing playing.')));
    }

    // Use positionProvider (just_audio's positionStream, ~200ms) for
    // the seek bar so it scrubs live; PlaybackState.updatePosition
    // only fires on state transitions and would leave the bar frozen
    // between them.
    final pos = ref.watch(positionProvider).value ?? Duration.zero;
    final dur = media.duration ?? Duration.zero;
    final isPlaying = playback?.playing == true;
    final shuffleOn = playback?.shuffleMode == AudioServiceShuffleMode.all;
    final repeatMode = playback?.repeatMode ?? AudioServiceRepeatMode.none;
    final actions = ref.read(playerActionsProvider);
    final albumId = (media.extras?['album_id'] as String?) ?? '';

    // Dominant-color gradient backdrop seeded from the current track's
    // album cover. While the color resolves (or when no cover exists),
    // the gradient collapses to a flat fs.obsidian — same look as
    // before the polish landed. Tweens to the new color on track change
    // via AnimatedContainer.
    final dominantAsync = ref.watch(albumColorProvider(albumId));
    final dominant = dominantAsync.asData?.value ?? fs.obsidian;
    // 0.55 alpha keeps the color present without overwhelming contrast
    // on the title / artist text below. The lower half of the screen
    // stays obsidian for control legibility.
    final gradientTop = dominant.withValues(alpha: 0.55);

    return Scaffold(
      backgroundColor: fs.obsidian,
      // The whole screen accepts vertical drag for dismissal. Buttons
      // and the seek slider are still tappable since gesture arena
      // gives priority to their child gesture detectors.
      body: GestureDetector(
        onVerticalDragStart: _onDragStart,
        onVerticalDragUpdate: _onDragUpdate,
        onVerticalDragEnd: _onDragEnd,
        behavior: HitTestBehavior.translucent,
        child: AnimatedContainer(
          duration: _trackChangeDuration,
          decoration: BoxDecoration(
            gradient: LinearGradient(
              begin: Alignment.topCenter,
              end: Alignment.bottomCenter,
              colors: [gradientTop, fs.obsidian],
              stops: const [0.0, 0.7],
            ),
          ),
          child: SafeArea(
          child: Column(
            children: [
              _TopBar(fs: fs),
              Expanded(
                child: Padding(
                  padding: const EdgeInsets.symmetric(horizontal: 24),
                  child: Column(
                    children: [
                      const Spacer(),
                      AnimatedSwitcher(
                        duration: _trackChangeDuration,
                        child: KeyedSubtree(
                          key: ValueKey('cover-${media.id}'),
                          child: _AlbumArt(
                              media: media, albumId: albumId, fs: fs),
                        ),
                      ),
                      const SizedBox(height: 28),
                      AnimatedSwitcher(
                        duration: _trackChangeDuration,
                        child: KeyedSubtree(
                          key: ValueKey('title-${media.id}'),
                          child: _TitleRow(media: media, fs: fs),
                        ),
                      ),
                      const SizedBox(height: 4),
                      AnimatedSwitcher(
                        duration: _trackChangeDuration,
                        child: Column(
                          key: ValueKey('artist-album-${media.id}'),
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            Text(
                              media.artist ?? '',
                              style: TextStyle(color: fs.ash, fontSize: 14),
                              maxLines: 1,
                              overflow: TextOverflow.ellipsis,
                            ),
                            if ((media.album ?? '').isNotEmpty) ...[
                              const SizedBox(height: 2),
                              Text(
                                media.album!,
                                style: TextStyle(color: fs.ash, fontSize: 12),
                                maxLines: 1,
                                overflow: TextOverflow.ellipsis,
                              ),
                            ],
                          ],
                        ),
                      ),
                      const SizedBox(height: 24),
                      _SecondaryControls(
                        fs: fs,
                        actions: actions,
                        shuffleOn: shuffleOn,
                        repeatMode: repeatMode,
                        media: media,
                      ),
                      const SizedBox(height: 8),
                      _SeekRow(position: pos, duration: dur, fs: fs, ref: ref),
                      const SizedBox(height: 24),
                      _PrimaryControls(
                        fs: fs,
                        ref: ref,
                        isPlaying: isPlaying,
                      ),
                      const SizedBox(height: 24),
                    ],
                  ),
                ),
              ),
            ],
          ),
          ),
        ),
      ),
    );
  }
}

class _TopBar extends StatelessWidget {
  const _TopBar({required this.fs});
  final FabledSwordTheme fs;

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 48,
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 4),
        child: Row(children: [
          IconButton(
            icon: Icon(Icons.expand_more, color: fs.parchment),
            tooltip: 'Close',
            onPressed: () => Navigator.of(context).maybePop(),
          ),
          const Spacer(),
          IconButton(
            icon: Icon(Icons.queue_music, color: fs.parchment),
            tooltip: 'Queue',
            onPressed: () => GoRouter.of(context).push('/queue'),
          ),
        ]),
      ),
    );
  }
}

class _AlbumArt extends StatelessWidget {
  const _AlbumArt({required this.media, required this.albumId, required this.fs});
  final MediaItem media;
  final String albumId;
  final FabledSwordTheme fs;

  @override
  Widget build(BuildContext context) {
    // Pick the best available source. AlbumCoverCache writes a file://
    // URI to media.artUri once the cover lands on disk; before then,
    // fall back to fetching via ServerImage from /api/albums/<id>/cover
    // (which carries the auth header and falls back gracefully on
    // failure).
    Widget cover;
    final artUri = media.artUri;
    if (artUri != null && artUri.isScheme('file')) {
      cover = Image(
        image: FileImage(File.fromUri(artUri)),
        fit: BoxFit.cover,
        errorBuilder: (_, __, ___) => Container(color: fs.slate),
      );
    } else if (albumId.isNotEmpty) {
      cover = ServerImage(
        url: '/api/albums/$albumId/cover',
        fit: BoxFit.cover,
        fallback: Container(color: fs.slate),
      );
    } else {
      cover = Container(color: fs.slate);
    }
    return AspectRatio(
      aspectRatio: 1,
      child: ConstrainedBox(
        constraints: const BoxConstraints(maxWidth: 320, maxHeight: 320),
        child: Hero(
          tag: kPlayerCoverHeroTag,
          // flightShuttleBuilder ensures the in-flight Hero renders the
          // destination's cover image (not the mini bar's small one)
          // during the entire animation, which reads as a smooth grow
          // rather than a swap mid-flight.
          flightShuttleBuilder:
              (_, __, ___, ____, toHeroContext) => toHeroContext.widget,
          child: ClipRRect(
            borderRadius: BorderRadius.circular(8),
            child: cover,
          ),
        ),
      ),
    );
  }
}

class _TitleRow extends StatelessWidget {
  const _TitleRow({required this.media, required this.fs});
  final MediaItem media;
  final FabledSwordTheme fs;

  @override
  Widget build(BuildContext context) {
    // Title-only — like + kebab moved into _SecondaryControls above
    // the seek bar so they share the same row as shuffle/repeat/queue.
    return Text(
      media.title,
      style: TextStyle(color: fs.parchment, fontSize: 22),
      maxLines: 1,
      overflow: TextOverflow.ellipsis,
      textAlign: TextAlign.center,
    );
  }
}

class _SeekRow extends StatelessWidget {
  const _SeekRow({
    required this.position,
    required this.duration,
    required this.fs,
    required this.ref,
  });
  final Duration position;
  final Duration duration;
  final FabledSwordTheme fs;
  final WidgetRef ref;

  String _fmt(Duration d) {
    final m = d.inMinutes.remainder(60).toString();
    final s = d.inSeconds.remainder(60).toString().padLeft(2, '0');
    return '$m:$s';
  }

  @override
  Widget build(BuildContext context) {
    final maxMs = duration.inMilliseconds.toDouble().clamp(1.0, double.infinity);
    return Column(children: [
      SliderTheme(
        data: SliderTheme.of(context).copyWith(
          trackHeight: 3,
          thumbShape: const RoundSliderThumbShape(enabledThumbRadius: 7),
          overlayShape: const RoundSliderOverlayShape(overlayRadius: 14),
        ),
        child: Slider(
          activeColor: fs.accent,
          inactiveColor: fs.slate,
          min: 0,
          max: maxMs,
          value: position.inMilliseconds
              .toDouble()
              .clamp(0.0, duration.inMilliseconds.toDouble()),
          onChanged: (v) => ref
              .read(audioHandlerProvider)
              .seek(Duration(milliseconds: v.toInt())),
        ),
      ),
      Padding(
        padding: const EdgeInsets.symmetric(horizontal: 4),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            Text(_fmt(position), style: TextStyle(color: fs.ash, fontSize: 11)),
            Text(_fmt(duration), style: TextStyle(color: fs.ash, fontSize: 11)),
          ],
        ),
      ),
    ]);
  }
}

class _PrimaryControls extends StatelessWidget {
  const _PrimaryControls({
    required this.fs,
    required this.ref,
    required this.isPlaying,
  });
  final FabledSwordTheme fs;
  final WidgetRef ref;
  final bool isPlaying;

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: [
        IconButton(
          iconSize: 36,
          icon: Icon(Icons.skip_previous, color: fs.parchment),
          onPressed: () => ref.read(audioHandlerProvider).skipToPrevious(),
        ),
        IconButton(
          iconSize: 72,
          icon: Icon(
            isPlaying ? Icons.pause_circle_filled : Icons.play_circle_filled,
            color: fs.accent,
          ),
          onPressed: () {
            final h = ref.read(audioHandlerProvider);
            if (isPlaying) {
              h.pause();
            } else {
              h.play();
            }
          },
        ),
        IconButton(
          iconSize: 36,
          icon: Icon(Icons.skip_next, color: fs.parchment),
          onPressed: () => ref.read(audioHandlerProvider).skipToNext(),
        ),
      ],
    );
  }
}

/// Action row sitting just above the seek bar. Holds shuffle / repeat
/// / queue plus the like + kebab that used to live in the title row,
/// so the title can sit truly centered above and this row carries
/// every per-track action in one place.
class _SecondaryControls extends StatelessWidget {
  const _SecondaryControls({
    required this.fs,
    required this.actions,
    required this.shuffleOn,
    required this.repeatMode,
    required this.media,
  });
  final FabledSwordTheme fs;
  final PlayerActions actions;
  final bool shuffleOn;
  final AudioServiceRepeatMode repeatMode;
  final MediaItem media;

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: [
        IconButton(
          tooltip: shuffleOn ? 'Shuffle on' : 'Shuffle off',
          icon: Icon(
            Icons.shuffle,
            color: shuffleOn ? fs.accent : fs.ash,
          ),
          onPressed: actions.toggleShuffle,
        ),
        IconButton(
          tooltip: switch (repeatMode) {
            AudioServiceRepeatMode.none => 'Repeat off',
            AudioServiceRepeatMode.one => 'Repeat one',
            _ => 'Repeat all',
          },
          icon: Icon(
            repeatMode == AudioServiceRepeatMode.one
                ? Icons.repeat_one
                : Icons.repeat,
            color: repeatMode == AudioServiceRepeatMode.none
                ? fs.ash
                : fs.accent,
          ),
          onPressed: actions.cycleRepeat,
        ),
        IconButton(
          tooltip: 'Queue',
          icon: Icon(Icons.queue_music, color: fs.ash),
          onPressed: () => GoRouter.of(context).push('/queue'),
        ),
        LikeButton(kind: LikeKind.track, id: media.id, size: 22),
        TrackActionsButton(
          track: TrackRef(
            id: media.id,
            title: media.title,
            albumId: (media.extras?['album_id'] as String?) ?? '',
            albumTitle: media.album ?? '',
            artistId: (media.extras?['artist_id'] as String?) ?? '',
            artistName: media.artist ?? '',
            durationSec: media.duration?.inSeconds ?? 0,
            streamUrl: '',
          ),
          hideQueueActions: true,
          // /now-playing lives outside the ShellRoute. Pushing
          // /artists/:id or /albums/:id (both shell-children) on top
          // of it would make go_router try to mount a duplicate
          // ShellRoute (the same _debugCheckDuplicatedPageKeys crash
          // we hit before with /queue). Await our own pop fully
          // before pushing the destination so go_router never sees
          // both pages active in the same frame.
          onNavigate: (path) async {
            await Navigator.of(context).maybePop();
            if (context.mounted) GoRouter.of(context).push(path);
          },
        ),
      ],
    );
  }
}