import 'package:halkyon_learn_flutter/src/feature/card/model/card_content.dart';
import 'package:halkyon_learn_flutter/src/feature/dictionary/data/dictionary_gateway.dart';
import 'package:halkyon_learn_flutter/src/feature/dictionary/model/dictionary.dart';

/// JMdict in English, as an instance that loaded it lists it.
const jmdict = Dictionary(
  source: 'jmdict',
  sourceVersion: '3.6.2 (2026-10-05)',
  kind: DictionaryKind.words,
  language: 'ja',
  glossLanguage: 'en',
  license: 'CC-BY-SA-4.0',
  credits: [
    (
      name: 'JMdict',
      by: 'Electronic Dictionary Research and Development Group (EDRDG)',
      license: 'CC-BY-SA-4.0',
      url: 'https://www.edrdg.org/edrdg/licence.html',
    ),
  ],
  entryCount: 3,
);

/// KANJIDIC2 in English, with the kana, as an instance that loaded it lists
/// it.
const kanjidic = Dictionary(
  source: 'kanjidic',
  sourceVersion: '2026-282',
  kind: DictionaryKind.characters,
  language: 'ja',
  glossLanguage: 'en',
  license: 'CC-BY-SA-4.0',
  credits: [
    (
      name: 'KANJIDIC2',
      by: 'Electronic Dictionary Research and Development Group (EDRDG)',
      license: 'CC-BY-SA-4.0',
      url: 'https://www.edrdg.org/edrdg/licence.html',
    ),
  ],
  entryCount: 2,
);

/// German words with English meanings from Wiktionary, as an instance that
/// loaded them lists them.
const wiktionaryDe = Dictionary(
  source: 'wiktionary-de',
  sourceVersion: '2026-10-03',
  kind: DictionaryKind.words,
  language: 'de',
  glossLanguage: 'en',
  license: 'CC-BY-SA-4.0',
  credits: [
    (
      name: 'Wiktionary',
      by: 'Wiktionary contributors',
      license: 'CC-BY-SA-4.0',
      url: 'https://en.wiktionary.org/wiki/Wiktionary:Copyrights',
    ),
  ],
  entryCount: 4,
);

/// Chinese words of CC-CEDICT in simplified characters.
const ccCedictHans = Dictionary(
  source: 'cc-cedict-hans',
  sourceVersion: '2026-10-14',
  kind: DictionaryKind.words,
  language: 'zh-Hans',
  glossLanguage: 'en',
  license: 'CC-BY-SA-4.0',
  credits: [
    (
      name: 'CC-CEDICT',
      by: 'MDBG',
      license: 'CC-BY-SA-4.0',
      url: 'https://www.mdbg.net/chinese/dictionary?page=cc-cedict',
    ),
  ],
  entryCount: 0,
);

/// Chinese characters of Unihan in simplified writing.
const unihanHans = Dictionary(
  source: 'unihan-hans',
  sourceVersion: '18.0.0',
  kind: DictionaryKind.characters,
  language: 'zh-Hans',
  glossLanguage: 'en',
  license: 'Unicode-3.0',
  credits: [
    (
      name: 'Unihan Database',
      by: 'Unicode, Inc.',
      license: 'Unicode-3.0',
      url: 'https://www.unicode.org/reports/tr38/',
    ),
  ],
  entryCount: 1,
);

/// Greek words with English meanings from Wiktionary.
const wiktionaryEl = Dictionary(
  source: 'wiktionary-el',
  sourceVersion: '2026-10-03',
  kind: DictionaryKind.words,
  language: 'el',
  glossLanguage: 'en',
  license: 'CC-BY-SA-4.0',
  credits: [
    (
      name: 'Wiktionary',
      by: 'Wiktionary contributors',
      license: 'CC-BY-SA-4.0',
      url: 'https://en.wiktionary.org/wiki/Wiktionary:Copyrights',
    ),
  ],
  entryCount: 0,
);

/// The Greek alphabet the curator writes.
const greekAlphabet = Dictionary(
  source: 'greek-alphabet',
  sourceVersion: '1',
  kind: DictionaryKind.characters,
  language: 'el',
  glossLanguage: 'en',
  license: 'CC0-1.0',
  credits: [
    (
      name: 'Alphabets (Hangul, Greek)',
      by: 'Halkyon Learn contributors',
      license: 'CC0-1.0',
      url: 'https://code.halkyon.app/project-halkyon/halkyon_learn',
    ),
  ],
  entryCount: 1,
);

/// A German word of Wiktionary: [headword], its part of speech [pos] in
/// full, meaning [glosses], its [genders] and the [forms] that find it.
DictionaryWord germanWord(
  String headword, {
  required String pos,
  List<String> glosses = const [],
  List<String> genders = const [],
  List<String> forms = const [],
  List<String> labels = const [],
}) => DictionaryWord(
  ref: (source: 'wiktionary-de', id: '$headword/$pos'),
  headword: headword,
  reading: null,
  labels: labels,
  senses: [
    VocabularySense(glosses: glosses, pos: [pos]),
  ],
  partOfSpeech: pos,
  genders: genders,
  inflections: [for (final form in forms) WordInflection(form, const [])],
  language: 'de',
);

/// A JMdict word: [headword] read [reading], meaning [glosses], [labels]
/// and the parts of speech [pos] on its one sense.
DictionaryWord word(
  String id,
  String headword, {
  String? reading,
  List<String> glosses = const [],
  List<String> labels = const [],
  List<String> pos = const [],
  String? version,
}) => DictionaryWord(
  ref: (source: 'jmdict', id: id),
  headword: headword,
  reading: reading,
  labels: labels,
  senses: [VocabularySense(glosses: glosses, pos: pos)],
  version: version,
);

/// A KANJIDIC2 character: [headword] meaning [meanings], read [on] and
/// [kun], with [labels]; a kana with its [romaji]; or a character [of]
/// another dictionary of characters.
DictionaryCharacter character(
  String headword, {
  List<String> meanings = const [],
  List<String> on = const [],
  List<String> kun = const [],
  List<String> labels = const [],
  String? romaji,
  String? name,
  int? grade,
  int? strokes,
  String? version,
  Dictionary of = kanjidic,
}) => DictionaryCharacter(
  ref: (source: of.source, id: headword),
  name: name,
  language: of.language,
  headword: headword,
  labels: labels,
  meanings: meanings,
  onReadings: on,
  kunReadings: kun,
  romaji: romaji,
  grade: grade,
  strokes: strokes,
  version: version,
);

/// A [DictionaryGateway] in memory: an instance with the dictionaries
/// [available], holding the [words] (and characters) of each source in
/// their order. A search finds the entries whose headword, reading, a
/// meaning or a reading starts with the query.
class FakeDictionaryGateway({
  final List<Dictionary> available = const [jmdict],
  final List<DictionaryItem> words = const [],
}) implements DictionaryGateway {
  /// When set, every request fails with it.
  Exception? fail;

  /// How often the dictionaries were asked for.
  int asked = 0;

  @override
  Future<List<Dictionary>> dictionaries() async {
    asked++;
    if (fail case final error?) {
      throw error;
    }
    return available;
  }

  /// The entries of [dictionary].
  Iterable<DictionaryItem> _of(Dictionary dictionary) =>
      words.where((word) => word.ref.source == dictionary.source);

  @override
  Future<List<DictionaryItem>> search(
    Dictionary dictionary,
    String query,
  ) async {
    if (fail case final error?) {
      throw error;
    }
    final typed = query.trim().toLowerCase();
    return [
      for (final item in _of(dictionary))
        if (switch (item) {
          DictionaryWord() => [
            item.headword,
            ?item.reading,
            for (final sense in item.senses) ...sense.glosses,
          ],
          DictionaryCharacter() => [
            item.headword,
            ...item.meaningsShown,
            ...item.onReadings,
            for (final reading in item.kunReadings) reading.replaceAll('.', ''),
          ],
        }.any((key) => key.toLowerCase().startsWith(typed)))
          item,
    ];
  }

  @override
  Future<List<DictionaryItem>> entries(
    Dictionary dictionary,
    List<String> ids,
  ) async {
    if (fail case final error?) {
      throw error;
    }
    final byId = {for (final item in _of(dictionary)) item.ref.id: item};
    return [for (final id in ids) ?byId[id]];
  }

  /// How many keys [withKeys] was asked for each time.
  final keysAsked = <int>[];

  /// By its headword and its reading, as typed: the curator's keys hold
  /// both, the reading also in hiragana; a word of Wiktionary also by its
  /// headword and inflections in lower case, as its text keys hold them.
  @override
  Future<Map<String, List<DictionaryItem>>> withKeys(
    Dictionary dictionary,
    List<String> keys,
  ) async {
    if (fail case final error?) {
      throw error;
    }
    keysAsked.add(keys.length);
    final asked = keys.toSet();
    final byKey = <String, List<DictionaryItem>>{};
    for (final item in _of(dictionary)) {
      for (final key in {
        item.headword,
        if (item case DictionaryWord(:final reading?)) reading,
        if (item case DictionaryWord(partOfSpeech: _?, :final inflections)) ...[
          item.headword.toLowerCase(),
          for (final form in inflections) form.text.toLowerCase(),
        ],
      }) {
        if (asked.contains(key)) {
          (byKey[key] ??= []).add(item);
        }
      }
    }
    return byKey;
  }

  /// How often [changed] was asked, and with how many entries each time.
  final changedAsked = <int>[];

  @override
  Future<List<DictionaryItem>> changed(
    Dictionary dictionary,
    Map<String, String> versions,
  ) async {
    if (fail case final error?) {
      throw error;
    }
    changedAsked.add(versions.length);
    return [
      for (final item in _of(dictionary))
        if (versions[item.ref.id] case final kept?)
          if (item.version != null && item.version != kept) item,
    ];
  }

  @override
  Future<int> countLabelled(Dictionary dictionary, String label) async {
    if (fail case final error?) {
      throw error;
    }
    return _of(dictionary).where((word) => word.labels.contains(label)).length;
  }

  @override
  Future<List<DictionaryItem>> labelled(
    Dictionary dictionary,
    String label, {
    required int offset,
    required int limit,
  }) async {
    if (fail case final error?) {
      throw error;
    }
    return _of(dictionary)
        .where((word) => word.labels.contains(label))
        .skip(offset)
        .take(limit)
        .toList();
  }
}