import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:cached_network_image/cached_network_image.dart';
import 'package:worldhopper/config/constants.dart';
import 'package:worldhopper/models/opds_entry.dart';
import 'package:worldhopper/providers/reading_progress_provider.dart';
import 'package:worldhopper/providers/connectivity_provider.dart';
import 'package:worldhopper/models/reading_progress.dart';
import 'package:uuid/uuid.dart';

/// Screen displaying publication details
class PublicationDetailScreen extends ConsumerWidget {
  final OPDSEntry entry;
  final String serverId;

  const PublicationDetailScreen({
    super.key,
    required this.entry,
    required this.serverId,
  });

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final progressKey = ProgressKey(
      publicationId: entry.id,
      serverId: serverId,
    );
    final progressAsync = ref.watch(readingProgressProvider(progressKey));

    return Scaffold(
      body: CustomScrollView(
        slivers: [
          _buildAppBar(context, ref),
          SliverToBoxAdapter(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                _buildHeader(context),
                const SizedBox(height: 24),
                _buildMetadata(context),
                const SizedBox(height: 24),
                if (entry.summary != null || entry.content != null) ...[
                  _buildDescription(context),
                  const SizedBox(height: 24),
                ],
                _buildProgressCard(context, ref, progressAsync),
                const SizedBox(height: 24),
                _buildActionButtons(context, ref, progressAsync),
                const SizedBox(height: 32),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildAppBar(BuildContext context, WidgetRef ref) {
    // Watch connectivity state
    final connectivityState = ref.watch(connectivityStateProvider);

    // Check if offline (default to online while loading)
    final isOffline = connectivityState.whenOrNull(
          data: (isOnline) => !isOnline,
        ) ??
        false;

    return SliverAppBar(
      expandedHeight: 300,
      pinned: true,
      actions: isOffline
          ? [
              Padding(
                padding: const EdgeInsets.only(right: 8),
                child: Icon(
                  Icons.cloud_off,
                  color: Theme.of(context).colorScheme.error,
                  semanticLabel: 'Offline',
                ),
              ),
            ]
          : null,
      flexibleSpace: FlexibleSpaceBar(
        background: _buildCoverImage(context),
      ),
    );
  }

  Widget _buildCoverImage(BuildContext context) {
    final imageUrl = entry.coverUrl ?? entry.thumbnailUrl;

    if (imageUrl == null) {
      return Container(
        color: Theme.of(context).colorScheme.surfaceContainerHighest,
        child: Icon(
          Icons.book,
          size: 100,
          color: Theme.of(context).colorScheme.onSurface.withOpacity(0.3),
        ),
      );
    }

    return CachedNetworkImage(
      imageUrl: imageUrl,
      fit: BoxFit.cover,
      placeholder: (context, url) => Container(
        color: Theme.of(context).colorScheme.surfaceContainerHighest,
        child: const Center(child: CircularProgressIndicator()),
      ),
      errorWidget: (context, url, error) => Container(
        color: Theme.of(context).colorScheme.surfaceContainerHighest,
        child: Icon(
          Icons.broken_image,
          size: 100,
          color: Theme.of(context).colorScheme.error,
        ),
      ),
    );
  }

  Widget _buildHeader(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 24),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            entry.title,
            style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                  fontWeight: FontWeight.bold,
                ),
          ),
          if (entry.authors.isNotEmpty) ...[
            const SizedBox(height: 8),
            Text(
              entry.authors.join(', '),
              style: Theme.of(context).textTheme.titleMedium?.copyWith(
                    color: Theme.of(context)
                        .colorScheme
                        .onSurface
                        .withOpacity(0.7),
                  ),
            ),
          ],
        ],
      ),
    );
  }

  Widget _buildMetadata(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 24),
      child: Wrap(
        spacing: 12,
        runSpacing: 8,
        children: [
          if (entry.hasStreamLink)
            Chip(
              avatar: const Icon(Icons.auto_stories, size: 18),
              label: Text('${entry.streamLink!.pageCount} pages'),
            ),
          if (entry.categories.isNotEmpty)
            ...entry.categories.map(
              (category) => Chip(
                label: Text(category),
              ),
            ),
          if (entry.published != null)
            Chip(
              avatar: const Icon(Icons.calendar_today, size: 18),
              label: Text(_formatDate(entry.published!)),
            ),
        ],
      ),
    );
  }

  Widget _buildDescription(BuildContext context) {
    final description = entry.content ?? entry.summary ?? '';

    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 24),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Description',
            style: Theme.of(context).textTheme.titleLarge?.copyWith(
                  fontWeight: FontWeight.bold,
                ),
          ),
          const SizedBox(height: 12),
          Text(
            _stripHtml(description),
            style: Theme.of(context).textTheme.bodyMedium,
          ),
        ],
      ),
    );
  }

  Widget _buildProgressCard(
    BuildContext context,
    WidgetRef ref,
    AsyncValue<ReadingProgress?> progressAsync,
  ) {
    return progressAsync.when(
      data: (progress) {
        if (progress == null) return const SizedBox.shrink();

        return Padding(
          padding: const EdgeInsets.symmetric(horizontal: 24),
          child: Card(
            child: Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      Text(
                        'Reading Progress',
                        style: Theme.of(context).textTheme.titleMedium?.copyWith(
                              fontWeight: FontWeight.bold,
                            ),
                      ),
                      Text(
                        '${(progress.progressPercentage * 100).toInt()}%',
                        style: Theme.of(context).textTheme.titleMedium?.copyWith(
                              color: Theme.of(context).colorScheme.primary,
                              fontWeight: FontWeight.bold,
                            ),
                      ),
                    ],
                  ),
                  const SizedBox(height: 12),
                  LinearProgressIndicator(
                    value: progress.progressPercentage,
                    minHeight: 8,
                    borderRadius: BorderRadius.circular(4),
                  ),
                  const SizedBox(height: 8),
                  Text(
                    entry.isEpub
                        ? 'Last read: ${_formatDateTime(progress.lastReadAt)}'
                        : 'Page ${progress.currentPage + 1} of ${progress.totalPages}',
                    style: Theme.of(context).textTheme.bodySmall,
                  ),
                ],
              ),
            ),
          ),
        );
      },
      loading: () => const SizedBox.shrink(),
      error: (_, __) => const SizedBox.shrink(),
    );
  }

  Widget _buildActionButtons(
    BuildContext context,
    WidgetRef ref,
    AsyncValue<ReadingProgress?> progressAsync,
  ) {
    // Check if entry can be read (either as stream or EPUB)
    final canRead = entry.hasStreamLink || entry.isEpub;
    
    if (!canRead) {
      return Padding(
        padding: const EdgeInsets.symmetric(horizontal: 24),
        child: Card(
          color: Theme.of(context).colorScheme.errorContainer,
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: Row(
              children: [
                Icon(
                  Icons.info_outline,
                  color: Theme.of(context).colorScheme.onErrorContainer,
                ),
                const SizedBox(width: 12),
                Expanded(
                  child: Text(
                    'This publication cannot be read in the app',
                    style: TextStyle(
                      color: Theme.of(context).colorScheme.onErrorContainer,
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      );
    }

    return progressAsync.when(
      data: (progress) {
        final isStarted = progress != null && progress.isStarted;
        final isCompleted = progress != null && progress.isCompleted;

        return Padding(
          padding: const EdgeInsets.symmetric(horizontal: 24),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              FilledButton.icon(
                onPressed: () => _startReading(context, ref, progress),
                icon: Icon(isStarted ? Icons.play_arrow : Icons.play_circle),
                label: Text(
                  isStarted
                      ? (isCompleted ? 'Read Again' : 'Continue Reading')
                      : 'Start Reading',
                ),
                style: FilledButton.styleFrom(
                  padding: const EdgeInsets.symmetric(vertical: 16),
                ),
              ),
              if (isStarted && !isCompleted) ...[
                const SizedBox(height: 12),
                OutlinedButton.icon(
                  onPressed: () => _startFromBeginning(context, ref),
                  icon: const Icon(Icons.restart_alt),
                  label: const Text('Start from Beginning'),
                ),
              ],
            ],
          ),
        );
      },
      loading: () => const Center(child: CircularProgressIndicator()),
      error: (_, __) => const SizedBox.shrink(),
    );
  }

  void _startReading(
    BuildContext context,
    WidgetRef ref,
    ReadingProgress? progress,
  ) {
    // Route to appropriate reader based on content type
    if (entry.isEpub) {
      // Navigate to EPUB reader (CosmosEpub handles position restoration)
      context.push(
        AppConstants.routeEpubReader,
        extra: {
          'entry': entry,
          'serverId': serverId,
        },
      );
    } else if (entry.hasStreamLink) {
      // Navigate to image reader
      final initialPage = progress?.currentPage ?? 0;

      context.push(
        AppConstants.routeReader,
        extra: {
          'entry': entry,
          'serverId': serverId,
          'initialPage': initialPage,
        },
      );
    }
  }

  void _startFromBeginning(BuildContext context, WidgetRef ref) {
    // Reset progress based on content type
    if (entry.isEpub) {
      final progress = ReadingProgress(
        id: const Uuid().v4(),
        publicationId: entry.id,
        serverId: serverId,
        currentPage: 0,
        totalPages: 100, // Percentage-based for EPUB
        epubLocation: null, // Clear location to start from beginning
        lastReadAt: DateTime.now(),
      );

      ref.read(readingProgressNotifierProvider.notifier).saveProgress(progress);

      // Navigate to EPUB reader from beginning
      context.push(
        AppConstants.routeEpubReader,
        extra: {
          'entry': entry,
          'serverId': serverId,
        },
      );
    } else if (entry.hasStreamLink) {
      final progress = ReadingProgress(
        id: const Uuid().v4(),
        publicationId: entry.id,
        serverId: serverId,
        currentPage: 0,
        totalPages: entry.streamLink!.pageCount,
        lastReadAt: DateTime.now(),
      );

      ref.read(readingProgressNotifierProvider.notifier).saveProgress(progress);

      // Navigate to image reader from beginning
      context.push(
        AppConstants.routeReader,
        extra: {
          'entry': entry,
          'serverId': serverId,
          'initialPage': 0,
        },
      );
    }
  }

  String _formatDate(DateTime date) {
    return '${date.year}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}';
  }

  String _formatDateTime(DateTime dateTime) {
    final now = DateTime.now();
    final difference = now.difference(dateTime);

    if (difference.inDays == 0) {
      if (difference.inHours == 0) {
        if (difference.inMinutes == 0) {
          return 'Just now';
        }
        return '${difference.inMinutes} min ago';
      }
      return '${difference.inHours} hour${difference.inHours > 1 ? 's' : ''} ago';
    } else if (difference.inDays == 1) {
      return 'Yesterday';
    } else if (difference.inDays < 7) {
      return '${difference.inDays} days ago';
    } else {
      return _formatDate(dateTime);
    }
  }

  String _stripHtml(String html) {
    return html.replaceAll(RegExp(r'<[^>]*>'), '').trim();
  }
}