import 'dart:async';
import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../../core/theme/app_colors.dart';
import '../../core/widgets/app_icon.dart';
import '../../core/widgets/pressable.dart';
import '../../data/models/jellyfin_library.dart';
import '../../data/services/jellyfin_library_service.dart';
import '../settings/jellyfin_controller.dart';
import 'jellyfin_album_screen.dart';
import 'jellyfin_dashboard_controller.dart';
import 'jellyfin_playback_controller.dart';
import 'widgets/jellyfin_back_button.dart';
import 'widgets/jellyfin_status_strip.dart';

class JellyfinDashboardScreen extends StatelessWidget {
  const JellyfinDashboardScreen({super.key, this.openAlbum});

  /// When set, the album page is pushed once the dashboard is mounted. Used
  /// when Home is tapped while a Jellyfin album is already playing, so Back
  /// from the album lands on Albums instead of Home.
  final JellyfinAlbum? openAlbum;

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
      create: (context) {
        final controller = JellyfinDashboardController(
          library: context.read<JellyfinLibraryService>(),
          jellyfin: context.read<JellyfinController>(),
        );
        unawaited(controller.load());
        return controller;
      },
      child: _JellyfinDashboardRoute(openAlbum: openAlbum),
    );
  }
}

class _JellyfinDashboardRoute extends StatefulWidget {
  const _JellyfinDashboardRoute({this.openAlbum});

  final JellyfinAlbum? openAlbum;

  @override
  State<_JellyfinDashboardRoute> createState() =>
      _JellyfinDashboardRouteState();
}

class _JellyfinDashboardRouteState extends State<_JellyfinDashboardRoute> {
  @override
  void initState() {
    super.initState();
    final album = widget.openAlbum;
    if (album == null) return;
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      Navigator.of(context).push(
        MaterialPageRoute<void>(
          builder: (_) => JellyfinAlbumScreen(album: album),
        ),
      );
    });
  }

  @override
  Widget build(BuildContext context) => const _JellyfinDashboardBody();
}

enum _JellyfinTab { albums, favorites }

class _JellyfinDashboardBody extends StatefulWidget {
  const _JellyfinDashboardBody();

  @override
  State<_JellyfinDashboardBody> createState() => _JellyfinDashboardBodyState();
}

class _JellyfinDashboardBodyState extends State<_JellyfinDashboardBody> {
  _JellyfinTab _tab = _JellyfinTab.albums;

  @override
  Widget build(BuildContext context) {
    final colors = context.colors;
    final theme = Theme.of(context);
    final dashboard = context.watch<JellyfinDashboardController>();
    final playback = context.watch<JellyfinPlaybackController>();
    final jellyfin = context.watch<JellyfinController>();
    final library = context.read<JellyfinLibraryService>();

    final currentId = playback.currentAlbum?.id;
    final currentPlaying = playback.playing || playback.buffering;
    final headers = library.imageHeaders;

    String? imageFor(JellyfinAlbum album) =>
        library.imageUrl(album.id, album.imageTag)?.toString();

    Widget favoritesBody(int columns) {
      final error = dashboard.favoritesError;
      if (error != null) {
        return _DashboardError(
          message: error,
          onRetry: () => unawaited(dashboard.retryFavorites()),
        );
      }
      if (dashboard.favoritesLoading && !dashboard.favoritesLoaded) {
        return const Center(child: CircularProgressIndicator());
      }
      if (dashboard.favorites.isEmpty) {
        return Center(
          child: Text(
            'No favorites',
            style: theme.textTheme.bodyLarge?.copyWith(color: colors.inkMuted),
          ),
        );
      }
      return GridView.builder(
        padding: const EdgeInsets.only(bottom: 8),
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: columns,
          crossAxisSpacing: 12,
          mainAxisSpacing: 14,
          childAspectRatio: 0.78,
        ),
        itemCount: dashboard.favorites.length,
        itemBuilder: (context, index) {
          final album = dashboard.favorites[index];
          return _AlbumCard(
            album: album,
            imageUrl: imageFor(album),
            headers: headers,
            isCurrent: currentId == album.id,
            isPlaying: currentPlaying && currentId == album.id,
            onTap: () => _openAlbum(context, dashboard, playback, album),
          );
        },
      );
    }

    Widget body(int columns) {
      if (_tab == _JellyfinTab.favorites) {
        return favoritesBody(columns);
      }
      if (dashboard.loading && !dashboard.hasLoaded) {
        return const Center(child: CircularProgressIndicator());
      }
      final error = dashboard.error;
      if (error != null) {
        return _DashboardError(
          message: error,
          onRetry: () => unawaited(dashboard.retry()),
        );
      }
      return Column(
        children: [
          Expanded(
            child: _AlbumSection(
              title: 'Recently played',
              albums: dashboard.latestPlayed,
              emptyText: 'Nothing played yet.',
              columns: columns,
              imageFor: imageFor,
              headers: headers,
              currentAlbumId: currentId,
              currentPlaying: currentPlaying,
              onPlay: (album) =>
                  _openAlbum(context, dashboard, playback, album),
            ),
          ),
          const SizedBox(height: 6),
          Expanded(
            child: _AlbumSection(
              title: 'Recently added',
              albums: dashboard.latestAdded,
              emptyText: 'No albums added yet.',
              columns: columns,
              imageFor: imageFor,
              headers: headers,
              currentAlbumId: currentId,
              currentPlaying: currentPlaying,
              onPlay: (album) =>
                  _openAlbum(context, dashboard, playback, album),
            ),
          ),
          const SizedBox(height: 6),
          Expanded(
            child: _AlbumSection(
              title: 'Random',
              albums: dashboard.random,
              emptyText: dashboard.hasGenres
                  ? 'No albums for the selected genres.'
                  : 'Choose up to 5 genres in Settings.',
              columns: columns,
              error: dashboard.randomError,
              shuffling: dashboard.randomLoading,
              onShuffle: dashboard.hasGenres ? dashboard.shuffle : null,
              imageFor: imageFor,
              headers: headers,
              currentAlbumId: currentId,
              currentPlaying: currentPlaying,
              onPlay: (album) => _openAlbum(
                context,
                dashboard,
                playback,
                album,
                shuffleAfter: true,
              ),
            ),
          ),
        ],
      );
    }

    return Scaffold(
      backgroundColor: colors.canvas,
      body: Container(
        decoration: homeBackground(colors, theme.brightness),
        child: SafeArea(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(36, 22, 36, 16),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                _DashboardHeader(serverName: jellyfin.serverName),
                const SizedBox(height: 10),
                _DashboardTabs(
                  selected: _tab,
                  onSelect: (tab) {
                    setState(() => _tab = tab);
                    if (tab == _JellyfinTab.favorites) {
                      unawaited(dashboard.loadFavorites());
                    }
                  },
                ),
                const SizedBox(height: 10),
                Expanded(
                  child: LayoutBuilder(
                    builder: (context, constraints) {
                      return body(_columnsFor(constraints.maxWidth));
                    },
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }

  static const _rowGap = 12.0;
  static const _minSixColumnWidth = 160.0;

  int _columnsFor(double width) {
    final sixColumnWidth = (width - _rowGap * 5) / 6;
    return sixColumnWidth >= _minSixColumnWidth ? 6 : 5;
  }

  void _openAlbum(
    BuildContext context,
    JellyfinDashboardController dashboard,
    JellyfinPlaybackController playback,
    JellyfinAlbum album, {
    bool shuffleAfter = false,
  }) {
    dashboard.markPlayed(album);
    final started = playback.playAlbum(album);
    if (shuffleAfter) {
      unawaited(
        started.then((error) async {
          if (error == null) await dashboard.shuffle();
        }),
      );
    } else {
      unawaited(started);
    }
    unawaited(
      Navigator.of(context)
          .push(
            MaterialPageRoute<void>(
              builder: (_) => JellyfinAlbumScreen(album: album),
            ),
          )
          .then((_) => dashboard.loadFavorites()),
    );
  }
}

class _DashboardHeader extends StatelessWidget {
  const _DashboardHeader({this.serverName});

  final String? serverName;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = context.colors;
    final name = serverName?.trim();
    return Row(
      children: [
        const JellyfinBackButton(),
        const SizedBox(width: 18),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text('Jellyfin', style: theme.textTheme.headlineLarge),
              const SizedBox(height: 2),
              Text(
                name == null || name.isEmpty
                    ? 'Music library'
                    : 'Music library · $name',
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
                style: theme.textTheme.bodySmall?.copyWith(
                  color: colors.inkMuted,
                ),
              ),
            ],
          ),
        ),
        const SizedBox(width: 12),
        const JellyfinStatusStrip(),
      ],
    );
  }
}

class _DashboardTabs extends StatelessWidget {
  const _DashboardTabs({required this.selected, required this.onSelect});

  final _JellyfinTab selected;
  final ValueChanged<_JellyfinTab> onSelect;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = context.colors;

    Widget tab(String label, _JellyfinTab value) {
      final isSelected = selected == value;
      return Pressable(
        onTap: () => onSelect(value),
        semanticLabel: label,
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(
              label,
              style: theme.textTheme.titleMedium?.copyWith(
                color: isSelected ? colors.ink : colors.inkMuted,
                fontWeight: isSelected ? FontWeight.w700 : FontWeight.w500,
              ),
            ),
            const SizedBox(height: 4),
            Container(
              width: 38,
              height: 2,
              decoration: BoxDecoration(
                color: isSelected ? colors.accent : Colors.transparent,
                borderRadius: BorderRadius.circular(2),
              ),
            ),
          ],
        ),
      );
    }

    return Row(
      children: [
        tab('Albums', _JellyfinTab.albums),
        const SizedBox(width: 28),
        tab('Favorites', _JellyfinTab.favorites),
        const SizedBox(width: 28),
        Text(
          'Artists',
          style: theme.textTheme.titleMedium?.copyWith(color: colors.inkFaint),
        ),
      ],
    );
  }
}

class _AlbumSection extends StatelessWidget {
  const _AlbumSection({
    required this.title,
    required this.albums,
    required this.emptyText,
    required this.columns,
    required this.imageFor,
    required this.headers,
    required this.currentAlbumId,
    required this.currentPlaying,
    required this.onPlay,
    this.error,
    this.shuffling = false,
    this.onShuffle,
  });

  final String title;
  final List<JellyfinAlbum> albums;
  final String emptyText;
  final int columns;
  final String? Function(JellyfinAlbum album) imageFor;
  final Map<String, String> headers;
  final String? currentAlbumId;
  final bool currentPlaying;
  final ValueChanged<JellyfinAlbum> onPlay;
  final String? error;
  final bool shuffling;
  final Future<void> Function()? onShuffle;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = context.colors;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Row(
          children: [
            Text(
              title,
              style: theme.textTheme.titleMedium?.copyWith(
                color: colors.ink,
                fontWeight: FontWeight.w700,
              ),
            ),
            if (onShuffle != null) ...[
              const Spacer(),
              _ShuffleButton(
                loading: shuffling,
                onTap: () => unawaited(onShuffle!()),
              ),
            ],
          ],
        ),
        const SizedBox(height: 6),
        Expanded(
          child: error != null
              ? Center(
                  child: Text(
                    error!,
                    textAlign: TextAlign.center,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: colors.danger,
                    ),
                  ),
                )
              : albums.isEmpty
              ? Center(
                  child: Text(
                    emptyText,
                    textAlign: TextAlign.center,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: colors.inkMuted,
                    ),
                  ),
                )
              : LayoutBuilder(
                  builder: (context, constraints) {
                    const gap = 12.0;
                    final width = math.max(
                      0.0,
                      (constraints.maxWidth - gap * (columns - 1)) / columns,
                    );
                    return Row(
                      crossAxisAlignment: CrossAxisAlignment.stretch,
                      children: [
                        for (var i = 0; i < columns; i++) ...[
                          if (i > 0) const SizedBox(width: gap),
                          SizedBox(
                            width: width,
                            child: i < albums.length
                                ? _AlbumCard(
                                    album: albums[i],
                                    imageUrl: imageFor(albums[i]),
                                    headers: headers,
                                    isCurrent: currentAlbumId == albums[i].id,
                                    isPlaying:
                                        currentPlaying &&
                                        currentAlbumId == albums[i].id,
                                    onTap: () => onPlay(albums[i]),
                                  )
                                : const SizedBox.shrink(),
                          ),
                        ],
                      ],
                    );
                  },
                ),
        ),
      ],
    );
  }
}

class _AlbumCard extends StatelessWidget {
  const _AlbumCard({
    required this.album,
    required this.imageUrl,
    required this.headers,
    required this.isCurrent,
    required this.isPlaying,
    required this.onTap,
  });

  final JellyfinAlbum album;
  final String? imageUrl;
  final Map<String, String> headers;
  final bool isCurrent;
  final bool isPlaying;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final colors = context.colors;
    final theme = Theme.of(context);
    return LayoutBuilder(
      builder: (context, constraints) {
        final cover = math.max(
          0.0,
          math.min(constraints.maxWidth, constraints.maxHeight - 46),
        );
        final placeholder = ColoredBox(
          color: colors.surfaceStrong,
          child: Center(
            child: AppIcon(
              'assets/icons/headphones.svg',
              size: 28,
              color: colors.inkFaint,
            ),
          ),
        );
        return Pressable(
          onTap: onTap,
          semanticLabel: 'Open ${album.name}',
          pressedScale: 0.97,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            mainAxisSize: MainAxisSize.min,
            children: [
              Container(
                width: cover,
                height: cover,
                clipBehavior: Clip.antiAlias,
                decoration: BoxDecoration(
                  borderRadius: BorderRadius.circular(15),
                  border: Border.all(
                    color: isCurrent ? colors.accent : colors.border,
                    width: isCurrent ? 2 : 1,
                  ),
                ),
                child: Stack(
                  fit: StackFit.expand,
                  children: [
                    if (imageUrl == null)
                      placeholder
                    else
                      Image.network(
                        imageUrl!,
                        headers: headers,
                        fit: BoxFit.cover,
                        errorBuilder: (_, _, _) => placeholder,
                      ),
                    if (isCurrent)
                      Align(
                        alignment: Alignment.bottomRight,
                        child: Container(
                          width: 26,
                          height: 26,
                          margin: const EdgeInsets.all(7),
                          decoration: BoxDecoration(
                            color: colors.canvas.withValues(alpha: 0.85),
                            shape: BoxShape.circle,
                          ),
                          child: Center(
                            child: AppIcon(
                              isPlaying
                                  ? 'assets/icons/volume-2.svg'
                                  : 'assets/icons/play.svg',
                              size: 13,
                              color: colors.accent,
                            ),
                          ),
                        ),
                      ),
                  ],
                ),
              ),
              const SizedBox(height: 6),
              Text(
                album.name,
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
                style: theme.textTheme.bodyMedium?.copyWith(
                  color: colors.ink,
                  fontWeight: FontWeight.w600,
                ),
              ),
              Text(
                album.artist.isEmpty ? 'Unknown artist' : album.artist,
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
                style: theme.textTheme.bodySmall?.copyWith(
                  color: colors.inkMuted,
                ),
              ),
            ],
          ),
        );
      },
    );
  }
}

class _ShuffleButton extends StatelessWidget {
  const _ShuffleButton({required this.loading, required this.onTap});

  final bool loading;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final colors = context.colors;
    return Pressable(
      onTap: loading ? null : onTap,
      semanticLabel: 'Shuffle random albums',
      pressedScale: 0.9,
      child: Container(
        width: 34,
        height: 34,
        decoration: BoxDecoration(
          color: colors.surfaceStrong,
          shape: BoxShape.circle,
          border: Border.all(color: colors.border),
        ),
        alignment: Alignment.center,
        child: loading
            ? SizedBox(
                width: 14,
                height: 14,
                child: CircularProgressIndicator(
                  strokeWidth: 2,
                  color: colors.accent,
                ),
              )
            : AppIcon(
                'assets/icons/refresh-cw.svg',
                size: 16,
                color: colors.inkMuted,
              ),
      ),
    );
  }
}

class _DashboardError extends StatelessWidget {
  const _DashboardError({required this.message, required this.onRetry});

  final String message;
  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    final colors = context.colors;
    final theme = Theme.of(context);
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Text(
            message,
            textAlign: TextAlign.center,
            style: theme.textTheme.bodyMedium?.copyWith(color: colors.inkMuted),
          ),
          const SizedBox(height: 10),
          TextButton(
            onPressed: onRetry,
            style: TextButton.styleFrom(foregroundColor: colors.accent),
            child: const Text('Retry'),
          ),
        ],
      ),
    );
  }
}