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

import '../data/database.dart';
import '../providers/providers.dart';
import '../sources/source.dart';
import 'widgets/comic_cover.dart';
import 'widgets/source_logo.dart';

class TitlePage extends ConsumerStatefulWidget {
  const TitlePage({super.key, required this.titleId});

  final int titleId;

  @override
  ConsumerState<TitlePage> createState() => _TitlePageState();
}

class _TitlePageState extends ConsumerState<TitlePage> {
  Title? _title;
  List<Chapter> _chapters = const [];
  final Set<int> _selected = {};
  bool _newestFirst = true;
  bool _loading = true;
  bool _syncing = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    _reload();
  }

  List<Chapter> _sortedReadingOrder(List<Chapter> chapters) {
    final copy = [...chapters];
    copy.sort((a, b) {
      final na = double.tryParse(a.chapterNumber ?? '') ?? 0;
      final nb = double.tryParse(b.chapterNumber ?? '') ?? 0;
      return na.compareTo(nb);
    });
    return copy;
  }

  Future<void> _reload({bool showLoading = true}) async {
    if (showLoading) {
      setState(() {
        _loading = true;
        _error = null;
      });
    }
    final db = ref.read(databaseProvider);
    final title = await db.getTitle(widget.titleId);
    final chapters =
        await db.listChapters(widget.titleId, newestFirst: _newestFirst);
    chapters.sort((a, b) {
      final na = double.tryParse(a.chapterNumber ?? '') ?? 0;
      final nb = double.tryParse(b.chapterNumber ?? '') ?? 0;
      return _newestFirst ? nb.compareTo(na) : na.compareTo(nb);
    });
    if (!mounted) return;
    setState(() {
      _title = title;
      _chapters = chapters;
      _loading = false;
    });
  }

  Future<void> _sync() async {
    final title = _title;
    if (title == null) return;
    setState(() => _syncing = true);
    try {
      final source = ref.read(sourceRegistryProvider).get(
            SourceId.values.byName(title.source),
          );
      final series = await source.fetchSeries(title.url);
      await ref.read(downloadQueueProvider).upsertSeries(series);
      await _reload();
    } catch (e) {
      if (!mounted) return;
      setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _syncing = false);
    }
  }

  Future<void> _downloadSelected() async {
    if (_selected.isEmpty) return;
    await ref.read(downloadQueueProvider).enqueueChapters(_selected);
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Queued ${_selected.length} chapter(s)')),
    );
    setState(() => _selected.clear());
    await _reload();
  }

  Future<void> _downloadAll() async {
    if (_chapters.isEmpty) return;
    var unreadOnly = true;
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (ctx) {
        return StatefulBuilder(
          builder: (ctx, setLocal) {
            final ids = _chapters.where((c) {
              if (c.status == 'downloaded') return false;
              if (unreadOnly && c.completed) return false;
              return true;
            }).map((c) => c.id).toList();
            return AlertDialog(
              title: const Text('Download all'),
              content: Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    ids.isEmpty
                        ? 'No chapters match the current filter.'
                        : 'Queue ${ids.length} chapter(s) for download?',
                  ),
                  const SizedBox(height: 12),
                  CheckboxListTile(
                    contentPadding: EdgeInsets.zero,
                    title: const Text('Download unread only'),
                    subtitle: const Text(
                      'Skip chapters already marked completed',
                    ),
                    value: unreadOnly,
                    onChanged: (v) => setLocal(() => unreadOnly = v ?? true),
                  ),
                ],
              ),
              actions: [
                TextButton(
                  onPressed: () => Navigator.pop(ctx, false),
                  child: const Text('Cancel'),
                ),
                FilledButton(
                  onPressed: ids.isEmpty
                      ? null
                      : () => Navigator.pop(ctx, true),
                  child: const Text('Download'),
                ),
              ],
            );
          },
        );
      },
    );
    if (confirmed != true || !mounted) return;
    final ids = _chapters.where((c) {
      if (c.status == 'downloaded') return false;
      if (unreadOnly && c.completed) return false;
      return true;
    }).map((c) => c.id);
    await ref.read(downloadQueueProvider).enqueueChapters(ids);
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Queued ${ids.length} chapter(s)')),
    );
    await _reload();
  }

  bool get _hasReadingHistory {
    final title = _title;
    if (title?.lastReadChapterId != null) return true;
    return _chapters.any((c) => c.lastReadAt != null || c.lastPage > 0 || c.completed);
  }

  Chapter? get _continueChapter {
    final title = _title;
    if (title?.lastReadChapterId != null) {
      final match =
          _chapters.where((c) => c.id == title!.lastReadChapterId).firstOrNull;
      if (match != null) return match;
    }
    Chapter? best;
    for (final c in _chapters) {
      if (c.lastReadAt == null && c.lastPage == 0 && !c.completed) continue;
      if (best == null) {
        best = c;
        continue;
      }
      final a = c.lastReadAt;
      final b = best.lastReadAt;
      if (a != null && (b == null || a.isAfter(b))) best = c;
    }
    return best;
  }

  Chapter? get _firstChapter {
    final ordered = _sortedReadingOrder(_chapters);
    return ordered.isEmpty ? null : ordered.first;
  }

  Future<void> _toggleInLibrary() async {
    final title = _title;
    if (title == null) return;
    final next = !title.inLibrary;
    await ref.read(databaseProvider).setInLibrary(title.id, next);
    ref.read(webDavSyncProvider).scheduleSync();
    await _reload();
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(next ? 'Added to Library' : 'Removed from Library'),
      ),
    );
  }

  void _openChapter(Chapter chapter) {
    context.push('/read/${widget.titleId}/${chapter.id}').then((_) async {
      if (!mounted) return;
      await _reload(showLoading: false);
    });
  }

  void _onReadOrContinue() {
    if (_hasReadingHistory) {
      final ch = _continueChapter ?? _firstChapter;
      if (ch != null) _openChapter(ch);
    } else {
      final ch = _firstChapter;
      if (ch != null) _openChapter(ch);
    }
  }

  Color? _statusColor(BuildContext context, Chapter ch) {
    final scheme = Theme.of(context).colorScheme;
    if (ch.completed) return scheme.primary;
    if (ch.status == 'downloaded') return scheme.tertiary;
    if (ch.status == 'downloading') return scheme.tertiary;
    if (ch.status == 'failed') return scheme.error;
    return null;
  }

  String _chapterSubtitle(Chapter ch) {
    final parts = <String>[];
    if (ch.completed) {
      parts.add('Completed');
    } else if (ch.pageCount > 0 && (ch.lastPage > 0 || ch.lastReadAt != null)) {
      parts.add('Page ${ch.lastPage + 1}/${ch.pageCount}');
    } else if (ch.lastReadAt != null || ch.lastPage > 0) {
      parts.add('Reading');
    }
    if (ch.status == 'downloaded') {
      parts.add('Downloaded');
    } else if (ch.status == 'downloading') {
      parts.add('Downloading');
    } else if (ch.status == 'failed') {
      parts.add('Failed');
    }
    return parts.isEmpty ? 'Unread' : parts.join(' · ');
  }

  @override
  Widget build(BuildContext context) {
    final title = _title;
    final canRead = _chapters.isNotEmpty;
    final continueLabel = _hasReadingHistory ? 'Continue' : 'Read first chapter';
    final continueChapter =
        _hasReadingHistory ? (_continueChapter ?? _firstChapter) : _firstChapter;

    return Scaffold(
      appBar: AppBar(
        title: Text(title?.title ?? 'Title'),
        actions: [
          if (title != null)
            IconButton(
              tooltip: title.inLibrary ? 'Remove from Library' : 'Add to Library',
              onPressed: _toggleInLibrary,
              icon: Icon(title.inLibrary ? Icons.star : Icons.star_border),
            ),
          IconButton(
            tooltip: 'Download all',
            onPressed: _chapters.isEmpty ? null : _downloadAll,
            icon: const Icon(Icons.download_for_offline_outlined),
          ),
          IconButton(
            tooltip: _newestFirst ? 'Oldest first' : 'Newest first',
            onPressed: () async {
              setState(() => _newestFirst = !_newestFirst);
              await _reload();
            },
            icon: Icon(_newestFirst ? Icons.arrow_downward : Icons.arrow_upward),
          ),
          IconButton(
            tooltip: 'Sync chapters',
            onPressed: _syncing ? null : _sync,
            icon: _syncing
                ? const SizedBox(
                    width: 20,
                    height: 20,
                    child: CircularProgressIndicator(strokeWidth: 2),
                  )
                : const Icon(Icons.sync),
          ),
        ],
      ),
      floatingActionButton: _selected.isEmpty
          ? null
          : FloatingActionButton.extended(
              onPressed: _downloadSelected,
              icon: const Icon(Icons.download),
              label: Text('Download ${_selected.length}'),
            ),
      body: _loading
          ? const Center(child: CircularProgressIndicator())
          : title == null
              ? const Center(child: Text('Title not found'))
              : Column(
                  children: [
                    if (_error != null)
                      MaterialBanner(
                        content: Text(_error!),
                        actions: [
                          TextButton(
                            onPressed: () => setState(() => _error = null),
                            child: const Text('Dismiss'),
                          ),
                        ],
                      ),
                    Padding(
                      padding: const EdgeInsets.all(12),
                      child: Row(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          SizedBox(
                            width: 96,
                            height: 128,
                            child: ClipRRect(
                              borderRadius: BorderRadius.circular(8),
                              child: ComicCover(
                                url: title.coverUrl,
                                sourceId: SourceId.tryParse(title.source),
                              ),
                            ),
                          ),
                          const SizedBox(width: 12),
                          Expanded(
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                Text(
                                  title.title,
                                  style: Theme.of(context).textTheme.titleLarge,
                                ),
                                const SizedBox(height: 4),
                                Row(
                                  children: [
                                    if (SourceId.tryParse(title.source)
                                        case final sourceId?)
                                      SourceLogo(
                                        sourceId: sourceId,
                                        size: 16,
                                        borderRadius: 4,
                                      ),
                                    if (SourceId.tryParse(title.source) != null)
                                      const SizedBox(width: 6),
                                    Expanded(
                                      child: Text(
                                        '${SourceId.tryParse(title.source)?.label ?? title.source} · ${_chapters.length} chapters',
                                        style:
                                            Theme.of(context).textTheme.bodySmall,
                                      ),
                                    ),
                                  ],
                                ),
                                if (title.description != null) ...[
                                  const SizedBox(height: 8),
                                  Text(
                                    title.description!,
                                    maxLines: 3,
                                    overflow: TextOverflow.ellipsis,
                                  ),
                                ],
                                if (canRead) ...[
                                  const SizedBox(height: 12),
                                  FilledButton.icon(
                                    onPressed: _onReadOrContinue,
                                    icon: Icon(
                                      _hasReadingHistory
                                          ? Icons.play_arrow
                                          : Icons.menu_book,
                                    ),
                                    label: Text(
                                      continueChapter == null
                                          ? continueLabel
                                          : _hasReadingHistory
                                              ? 'Continue · ${continueChapter.label}'
                                              : continueLabel,
                                    ),
                                  ),
                                ],
                              ],
                            ),
                          ),
                        ],
                      ),
                    ),
                    const Divider(height: 1),
                    Expanded(
                      child: ListView.builder(
                        itemCount: _chapters.length,
                        itemBuilder: (context, i) {
                          final ch = _chapters[i];
                          final selected = _selected.contains(ch.id);
                          return ListTile(
                            leading: Checkbox(
                              value: selected,
                              onChanged: (v) {
                                setState(() {
                                  if (v == true) {
                                    _selected.add(ch.id);
                                  } else {
                                    _selected.remove(ch.id);
                                  }
                                });
                              },
                            ),
                            title: Text(ch.label),
                            subtitle: Text(_chapterSubtitle(ch)),
                            trailing: Icon(
                              ch.completed
                                  ? Icons.check_circle
                                  : ch.status == 'downloaded'
                                      ? Icons.offline_pin
                                      : Icons.chevron_right,
                              color: _statusColor(context, ch),
                            ),
                            onTap: () => _openChapter(ch),
                            onLongPress: () {
                              setState(() {
                                if (selected) {
                                  _selected.remove(ch.id);
                                } else {
                                  _selected.add(ch.id);
                                }
                              });
                            },
                          );
                        },
                      ),
                    ),
                  ],
                ),
    );
  }
}