import '../models/jellyfin_library.dart';

/// A raw genre plus the canonical family it belongs to.
class JellyfinGenreMatch {
  const JellyfinGenreMatch({required this.id, required this.label});

  final String id;
  final String label;
}

/// Built-in grouping for Jellyfin genre tags. The rules intentionally prefer
/// the head noun ("Folk Metal" -> Metal, "Blues Rock" -> Rock) and then a
/// small alias table for hybrids and Cyrillic spellings. Anything unmatched
/// stays its own family so no library tag is lost.
class JellyfinGenreCatalog {
  const JellyfinGenreCatalog();

  static const _labels = <String, String>{
    'metal': 'Metal',
    'rock': 'Rock',
    'jazz': 'Jazz',
    'pop': 'Pop',
    'folk': 'Folk',
    'blues': 'Blues',
    'soul': 'Soul',
    'funk': 'Funk',
    'rnb': 'R&B',
    'country': 'Country',
    'classical': 'Classical',
    'soundtrack': 'Soundtrack',
    'electronic': 'Electronic',
    'ambient': 'Ambient',
    'punk': 'Punk',
    'latin': 'Latin',
    'acoustic': 'Acoustic',
    'avant-garde': 'Avant-Garde',
    'gothic': 'Gothic',
    'pagan': 'Pagan',
    'singer-songwriter': 'Singer-Songwriter',
    'comedy': 'Comedy',
  };

  static const _order = <String>[
    'metal',
    'rock',
    'jazz',
    'pop',
    'folk',
    'blues',
    'soul',
    'funk',
    'rnb',
    'country',
    'classical',
    'soundtrack',
    'electronic',
    'ambient',
    'punk',
    'latin',
    'acoustic',
    'avant-garde',
    'gothic',
    'pagan',
    'singer-songwriter',
    'comedy',
  ];

  /// Whole-name aliases that cannot be inferred from the last token.
  static const _aliases = <String, String>{
    'black': 'metal',
    'death': 'metal',
    'viking': 'metal',
    'doom': 'metal',
    'alternative': 'rock',
    'grunge': 'rock',
    'progressive': 'rock',
    'rockabilly': 'rock',
    'rock & roll': 'rock',
    'rock singer-songwriter': 'rock',
    'neofolk': 'folk',
    'medieval': 'folk',
    'composer': 'classical',
    'conductor': 'classical',
    'film scores': 'soundtrack',
    'films/games': 'soundtrack',
    'dungeon synth': 'ambient',
    'new age': 'ambient',
    'dance': 'electronic',
    'electro': 'electronic',
    'fusion': 'jazz',
    'swing': 'jazz',
    'hardcore': 'punk',
    'metalcore': 'metal',
    'deathcore': 'metal',
    'black metal': 'metal',
    'death metal': 'metal',
    'heavy metal': 'metal',
    'soul & funk': 'soul',
    'r&b': 'rnb',
    'latin music': 'latin',
    'rock pop': 'pop',
    'acoustic': 'acoustic',
    'avant-garde': 'avant-garde',
    'gothic': 'gothic',
    'pagan': 'pagan',
    'singer & songwriter': 'singer-songwriter',
    'comedy': 'comedy',
    'neoclassical': 'classical',
    'метъл': 'metal',
    'рок': 'rock',
    'хард рок': 'rock',
    'джаз': 'jazz',
    'поп': 'pop',
    'фолк': 'folk',
    'блус': 'blues',
    'кънтри': 'country',
    'класическа': 'classical',
    'електронна': 'electronic',
    'ембиънт': 'ambient',
    'пънк': 'punk',
    'соул': 'soul',
    'фънк': 'funk',
    'латино': 'latin',
  };

  /// Head nouns. The last token wins, which handles every "X Metal",
  /// "X Rock", "X Jazz" and "X Folk" variant without enumerating them.
  static const _headNouns = <String, String>{
    'metal': 'metal',
    'метъл': 'metal',
    'rock': 'rock',
    'рок': 'rock',
    'jazz': 'jazz',
    'джаз': 'jazz',
    'pop': 'pop',
    'поп': 'pop',
    'folk': 'folk',
    'фолк': 'folk',
    'blues': 'blues',
    'блус': 'blues',
    'soul': 'soul',
    'соул': 'soul',
    'funk': 'funk',
    'фънк': 'funk',
    'country': 'country',
    'кънтри': 'country',
    'classical': 'classical',
    'electronic': 'electronic',
    'ambient': 'ambient',
    'ембиънт': 'ambient',
    'punk': 'punk',
    'пънк': 'punk',
    'latin': 'latin',
    'латино': 'latin',
    'soundtrack': 'soundtrack',
  };

  List<JellyfinGenreFamily> group(Iterable<String> rawGenres) {
    final byFamily = <String, List<String>>{};
    final labels = <String, String>{};
    for (final raw in rawGenres) {
      final name = raw.trim();
      if (name.isEmpty) continue;
      final genreMatch = match(name);
      byFamily.putIfAbsent(genreMatch.id, () => []).add(name);
      labels[genreMatch.id] = genreMatch.label;
    }

    final families = <JellyfinGenreFamily>[];
    for (final id in _order) {
      final raws = byFamily[id];
      if (raws == null || raws.isEmpty) continue;
      families.add(
        JellyfinGenreFamily(
          id: id,
          label: labels[id] ?? _labels[id]!,
          rawGenres: List.unmodifiable(_sorted(raws)),
          isStandalone: false,
        ),
      );
    }

    final standalone =
        byFamily.keys
            .where((id) => !_order.contains(id))
            .toList(growable: false)
          ..sort(
            (a, b) => (labels[a] ?? a).toLowerCase().compareTo(
              (labels[b] ?? b).toLowerCase(),
            ),
          );
    for (final id in standalone) {
      families.add(
        JellyfinGenreFamily(
          id: id,
          label: labels[id] ?? id,
          rawGenres: List.unmodifiable(_sorted(byFamily[id]!)),
          isStandalone: true,
        ),
      );
    }
    return families;
  }

  JellyfinGenreMatch match(String raw) {
    final name = raw.trim();
    final normalized = _normalize(name);
    final alias = _aliases[normalized];
    if (alias != null) {
      return JellyfinGenreMatch(id: alias, label: _labels[alias]!);
    }

    final tokens = normalized.split(RegExp(r'[\s\-/&]+'));
    for (var i = tokens.length - 1; i >= 0; i--) {
      final token = tokens[i];
      if (token.isEmpty) continue;
      final head = _headNouns[token];
      if (head != null) {
        return JellyfinGenreMatch(id: head, label: _labels[head]!);
      }
      // Only the last meaningful token decides the head noun; stop after it.
      break;
    }

    for (final entry in _headNouns.entries) {
      if (normalized.endsWith(entry.key)) {
        return JellyfinGenreMatch(
          id: entry.value,
          label: _labels[entry.value]!,
        );
      }
    }

    return JellyfinGenreMatch(
      id: 'raw:$normalized',
      label: name.isEmpty ? raw : name,
    );
  }

  /// Expands saved family selections to the raw server tags the query needs.
  List<String> rawGenresFor({
    required List<JellyfinGenreFamily> families,
    required Iterable<String> selectedIds,
  }) {
    final selected = selectedIds.toSet();
    final result = <String>[];
    for (final family in families) {
      if (!selected.contains(family.id)) continue;
      for (final raw in family.rawGenres) {
        if (!result.contains(raw)) result.add(raw);
      }
    }
    return result;
  }

  /// Drops selections whose family disappeared from the server and refreshes
  /// their labels from the current catalog.
  List<JellyfinGenreSelection> resolveSelections({
    required List<JellyfinGenreFamily> families,
    required Iterable<JellyfinGenreSelection> selections,
  }) {
    final byId = {for (final family in families) family.id: family};
    final resolved = <JellyfinGenreSelection>[];
    for (final selection in selections) {
      final family = byId[selection.id];
      if (family == null) continue;
      resolved.add(JellyfinGenreSelection(id: family.id, label: family.label));
    }
    return resolved;
  }

  JellyfinGenreFamily? familyById(
    List<JellyfinGenreFamily> families,
    String id,
  ) {
    for (final family in families) {
      if (family.id == id) return family;
    }
    return null;
  }

  static List<String> _sorted(List<String> values) {
    final copy = values.toList(growable: true)
      ..sort((a, b) => a.toLowerCase().compareTo(b.toLowerCase()));
    return copy;
  }

  static String _normalize(String value) {
    var text = value.trim().toLowerCase();
    text = text.replaceAll('ё', 'е');
    text = text.replaceAll(RegExp(r'\s+'), ' ');
    text = text.replaceAll(RegExp(r'[\[\]\(\)\{\}"“”„]'), '');
    text = text.replaceAll(RegExp(r'\s*/\s*'), '/');
    text = text.replaceAll(RegExp(r'\s*&\s*'), ' & ');
    text = text.replaceAll(RegExp(r'\s*-\s*'), '-');
    text = text.replaceAll(RegExp(r'[.!?]+$'), '');
    return text.trim();
  }
}