import 'package:worldhopper/models/enhanced_metadata.dart';
import 'package:worldhopper/models/entry.dart';
import 'package:worldhopper/models/feed.dart';
import 'package:worldhopper/models/link.dart';
import 'package:worldhopper/models/stream_link.dart';
import 'package:worldhopper/services/kavita_api_client.dart';
import 'package:worldhopper/services/opds_parser.dart' show ParsedFeed;

/// Maps Kavita REST API JSON responses to [Feed]/[Entry] models.
///
/// This is a pure data-transformation layer — no HTTP calls. It produces
/// the same model objects that the OPDS parser would, so the UI layer
/// works identically for both server types.
class KavitaFeedMapper {
  final String baseUrl;
  final String apiKey;
  final KavitaApiClient _apiClient;

  KavitaFeedMapper({
    required this.baseUrl,
    required this.apiKey,
    required KavitaApiClient apiClient,
  }) : _apiClient = apiClient;

  // ---------------------------------------------------------------------------
  // Root → Libraries
  // ---------------------------------------------------------------------------

  /// Convert a list of LibraryDto → navigation [Feed].
  Feed mapLibrariesToFeed(List<Map<String, dynamic>> libraries) {
    final entries = libraries.map(_libraryToEntry).toList();
    return Feed(
      id: 'kavita-root',
      title: 'Libraries',
      entries: entries,
    );
  }

  Entry _libraryToEntry(Map<String, dynamic> lib) {
    final id = lib['id'] as int;
    final name = lib['name'] as String? ?? 'Library';

    return Entry(
      id: 'library-$id',
      title: name,
      links: [
        Link(rel: 'subsection', href: 'kavita://libraries/$id'),
      ],
    );
  }

  // ---------------------------------------------------------------------------
  // Library → Series
  // ---------------------------------------------------------------------------

  /// Convert a paginated series list → navigation [Feed].
  Feed mapSeriesToFeed(
    List<Map<String, dynamic>> series, {
    required int libraryId,
    int page = 1,
    int pageSize = 20,
    int? totalItems,
  }) {
    final entries = series.map(_seriesToEntry).toList();

    final links = <Link>[];
    // Pagination: add next link if there are more items
    if (totalItems != null && page * pageSize < totalItems) {
      links.add(Link(
        rel: 'next',
        href: 'kavita://libraries/$libraryId?page=${page + 1}',
      ));
    }

    return Feed(
      id: 'kavita-library-$libraryId',
      title: 'Series',
      entries: entries,
      links: links,
      totalResults: totalItems,
      itemsPerPage: pageSize,
      startIndex: (page - 1) * pageSize,
    );
  }

  Entry _seriesToEntry(Map<String, dynamic> series) {
    final id = series['id'] as int;
    final name = series['name'] as String? ?? 'Untitled';
    // Build cover URL
    final coverUrl = _apiClient.seriesCoverUrl(baseUrl, apiKey, id);

    return Entry(
      id: 'series-$id',
      title: name,
      coverUrl: coverUrl,
      thumbnailUrl: coverUrl,
      links: [
        Link(rel: 'subsection', href: 'kavita://series/$id'),
      ],
    );
  }

  // ---------------------------------------------------------------------------
  // Series → Volumes/Chapters (acquisition feed)
  // ---------------------------------------------------------------------------

  /// Convert series-detail → acquisition [ParsedFeed].
  ///
  /// Returns both the [Feed] and a metadata map for the publication cache.
  ParsedFeed mapSeriesDetailToFeed(
    Map<String, dynamic> detail, {
    required int seriesId,
    Map<String, dynamic>? seriesInfo,
  }) {
    final volumes =
        (detail['volumes'] as List?)?.cast<Map<String, dynamic>>() ?? [];
    final specials =
        (detail['specials'] as List?)?.cast<Map<String, dynamic>>() ?? [];

    final entries = <Entry>[];
    final metadata = <String, EnhancedMetadata>{};

    // Extract series name from seriesInfo if available
    final seriesName = seriesInfo?['name'] as String?;

    for (final volume in volumes) {
      final chapters =
          (volume['chapters'] as List?)?.cast<Map<String, dynamic>>() ?? [];

      if (chapters.length == 1) {
        // Single chapter in volume — show as single entry
        final chapter = chapters.first;
        final entry = _chapterToEntry(chapter, seriesId, volume: volume);
        entries.add(entry);
        if (seriesName != null) {
          metadata[entry.id] = EnhancedMetadata(series: seriesName);
        }
      } else {
        // Multiple chapters — show each chapter as an entry
        for (final chapter in chapters) {
          final entry = _chapterToEntry(chapter, seriesId, volume: volume);
          entries.add(entry);
          if (seriesName != null) {
            metadata[entry.id] = EnhancedMetadata(series: seriesName);
          }
        }
      }
    }

    // Add specials
    for (final special in specials) {
      final entry = _chapterToEntry(special, seriesId);
      entries.add(entry);
      if (seriesName != null) {
        metadata[entry.id] = EnhancedMetadata(series: seriesName);
      }
    }

    final feed = Feed(
      id: 'kavita-series-$seriesId',
      title: seriesName ?? 'Series',
      entries: entries,
    );

    return ParsedFeed(feed, metadata);
  }

  Entry _chapterToEntry(
    Map<String, dynamic> chapter,
    int seriesId, {
    Map<String, dynamic>? volume,
  }) {
    final chapterId = chapter['id'] as int;
    final pages = chapter['pages'] as int? ?? 0;
    final pagesRead = chapter['pagesRead'] as int? ?? 0;
    final volumeId = volume?['id'] as int? ?? chapter['volumeId'] as int? ?? 0;
    // Build title from volume/chapter info
    final title = _buildChapterTitle(chapter, volume: volume);

    // Determine content type from format
    // MangaFormat: 0=Image, 1=Archive, 2=Unknown, 3=Epub, 4=Pdf
    final format = chapter['format'] as int?;
    final isEpub = format == 3;

    // Build cover URL
    final coverUrl = _apiClient.chapterCoverUrl(baseUrl, apiKey, chapterId);

    // Build links — embed seriesId/volumeId/chapterId in the download URL
    // so markAsRead can extract them later.
    final links = <Link>[];
    if (isEpub) {
      links.add(Link(
        rel: 'http://opds-spec.org/acquisition/open-access',
        href:
            '$baseUrl/api/Download/chapter?chapterId=$chapterId&seriesId=$seriesId&volumeId=$volumeId',
        type: 'application/epub+zip',
      ));
    } else {
      links.add(Link(
        rel: 'http://opds-spec.org/acquisition/open-access',
        href:
            '$baseUrl/api/Download/chapter?chapterId=$chapterId&seriesId=$seriesId&volumeId=$volumeId',
        type: 'application/zip',
      ));
    }

    // Build StreamLink for non-EPUB (image-based reading)
    StreamLink? streamLink;
    if (!isEpub && pages > 0) {
      streamLink = StreamLink(
        href: _apiClient.pageImageUrlTemplate(baseUrl, apiKey, chapterId),
        type: 'image/jpeg',
        pageCount: pages,
        lastRead: pagesRead > 0 ? pagesRead - 1 : null, // Convert to 0-indexed
      );
    }

    // Authors from chapter writers
    final writers = (chapter['writers'] as List?)
            ?.map((w) => (w as Map<String, dynamic>)['name'] as String? ?? '')
            .where((n) => n.isNotEmpty)
            .toList() ??
        [];

    // Summary
    final summary = chapter['summary'] as String?;

    return Entry(
      id: 'chapter-$chapterId',
      title: title,
      summary: summary != null && summary.isNotEmpty ? summary : null,
      authors: writers,
      links: links,
      streamLink: streamLink,
      coverUrl: coverUrl,
      thumbnailUrl: coverUrl,
    );
  }

  String _buildChapterTitle(
    Map<String, dynamic> chapter, {
    Map<String, dynamic>? volume,
  }) {
    final isSpecial = chapter['isSpecial'] as bool? ?? false;
    final titleName = chapter['titleName'] as String?;
    final chapterNumber = chapter['number'] as String?;
    final chapterRange = chapter['range'] as String?;

    if (isSpecial && titleName != null && titleName.isNotEmpty) {
      return titleName;
    }

    // If volume is provided, include volume info
    if (volume != null) {
      final volumeName = volume['name'] as String?;
      final minNumber = volume['minNumber'] as num?;

      // If the volume has a meaningful number and the chapter is the only one
      if (minNumber != null && minNumber > 0) {
        if (titleName != null && titleName.isNotEmpty) {
          return 'Vol. ${minNumber.toInt()} - $titleName';
        }
        return 'Volume ${minNumber.toInt()}';
      }

      if (volumeName != null && volumeName.isNotEmpty) {
        return volumeName;
      }
    }

    // Fall back to chapter info
    if (titleName != null && titleName.isNotEmpty) {
      return titleName;
    }
    if (chapterRange != null && chapterRange.isNotEmpty) {
      return 'Chapter $chapterRange';
    }
    if (chapterNumber != null && chapterNumber != '0') {
      return 'Chapter $chapterNumber';
    }

    return 'Chapter';
  }
}