import 'dart:async';
import 'package:sqflite/sqflite.dart';
import '../models/kanji_item.dart';
import '../models/srs_item.dart';
import '../api/wk_client.dart';
import 'database_constants.dart';
import 'database_helper.dart';

import 'package:flutter_dotenv/flutter_dotenv.dart';

class DeckRepository {
  String? _apiKey;

  Future<void> setApiKey(String apiKey) async {
    _apiKey = apiKey;
    await saveApiKey(apiKey);
  }

  String? get apiKey => _apiKey;

  Future<void> saveApiKey(String apiKey) async {
    final db = await DatabaseHelper().db;
    await db.insert(DbConstants.settingsTable, {
      DbConstants.keyColumn: 'apiKey',
      DbConstants.valueColumn: apiKey,
    }, conflictAlgorithm: ConflictAlgorithm.replace);
  }

  Future<String?> loadApiKey() async {
    final db = await DatabaseHelper().db;
    final rows = await db.query(
      DbConstants.settingsTable,
      where: '${DbConstants.keyColumn} = ?',
      whereArgs: ['apiKey'],
    );

    if (rows.isNotEmpty) {
      _apiKey = rows.first[DbConstants.valueColumn] as String;
      return _apiKey;
    }

    try {
      final envApiKey = dotenv.env['WANIKANI_API_KEY'];
      if (envApiKey != null && envApiKey.isNotEmpty) {
        await saveApiKey(envApiKey);
        _apiKey = envApiKey;
        return _apiKey;
      }
    } catch (e) {
      // dotenv is not initialized
    }

    return null;
  }

  Future<void> saveKanji(List<KanjiItem> items) async {
    final db = await DatabaseHelper().db;
    final batch = db.batch();
    for (final it in items) {
      batch.insert(DbConstants.kanjiTable, {
        DbConstants.idColumn: it.id,
        DbConstants.levelColumn: it.level,
        DbConstants.charactersColumn: it.characters,
        DbConstants.meaningsColumn: it.meanings.join('|'),
        DbConstants.onyomiColumn: it.onyomi.join('|'),
        DbConstants.kunyomiColumn: it.kunyomi.join('|'),
      }, conflictAlgorithm: ConflictAlgorithm.replace);
    }
    await batch.commit(noResult: true);
  }

  Future<List<KanjiItem>> loadKanji() async {
    final db = await DatabaseHelper().db;
    final rows = await db.query(DbConstants.kanjiTable);
    final kanjiItems = rows
        .map(
          (r) => KanjiItem(
            id: r[DbConstants.idColumn] as int,
            level: r[DbConstants.levelColumn] as int? ?? 0,
            characters: r[DbConstants.charactersColumn] as String,
            meanings: (r[DbConstants.meaningsColumn] as String)
                .split('|')
                .where((s) => s.isNotEmpty)
                .toList(),
            onyomi: (r[DbConstants.onyomiColumn] as String)
                .split('|')
                .where((s) => s.isNotEmpty)
                .toList(),
            kunyomi: (r[DbConstants.kunyomiColumn] as String)
                .split('|')
                .where((s) => s.isNotEmpty)
                .toList(),
          ),
        )
        .toList();

    final srsRows = await db.query(DbConstants.srsItemsTable);
    final srsItemsByKanjiId = <int, List<SrsItem>>{};
    for (final r in srsRows) {
      final srsItem = SrsItem(
        subjectId: r[DbConstants.kanjiIdColumn] as int,
        quizMode: QuizMode.values.firstWhere(
          (e) => e.toString() == r[DbConstants.quizModeColumn] as String,
        ),
        readingType: r[DbConstants.readingTypeColumn] as String?,
        srsStage: r[DbConstants.srsStageColumn] as int,
        lastAsked: DateTime.parse(r[DbConstants.lastAskedColumn] as String),
      );
      srsItemsByKanjiId.putIfAbsent(srsItem.subjectId, () => []).add(srsItem);
    }

    for (final item in kanjiItems) {
      final srsItems = srsItemsByKanjiId[item.id] ?? [];
      for (final srsItem in srsItems) {
        final key = srsItem.quizMode.toString() + (srsItem.readingType ?? '');
        item.srsItems[key] = srsItem;
      }
    }

    return kanjiItems;
  }

  Future<void> updateSrsItem(SrsItem item) async {
    final db = await DatabaseHelper().db;
    await db.update(
      DbConstants.srsItemsTable,
      {
        DbConstants.srsStageColumn: item.srsStage,
        DbConstants.lastAskedColumn: item.lastAsked.toIso8601String(),
      },
      where: '${DbConstants.kanjiIdColumn} = ? AND ${DbConstants.quizModeColumn} = ? AND ${DbConstants.readingTypeColumn} = ?',
      whereArgs: [item.subjectId, item.quizMode.toString(), item.readingType],
    );
  }

  Future<void> insertSrsItem(SrsItem item) async {
    final db = await DatabaseHelper().db;
    await db.insert(DbConstants.srsItemsTable, {
      DbConstants.kanjiIdColumn: item.subjectId,
      DbConstants.quizModeColumn: item.quizMode.toString(),
      DbConstants.readingTypeColumn: item.readingType,
      DbConstants.srsStageColumn: item.srsStage,
      DbConstants.lastAskedColumn: item.lastAsked.toIso8601String(),
    }, conflictAlgorithm: ConflictAlgorithm.replace);
  }

  Future<List<KanjiItem>> fetchAndCacheFromWk([String? apiKey]) async {
    final key = apiKey ?? _apiKey;
    if (key == null) throw Exception('API key not set');

    final client = WkClient(key);
    final assignments = await client.fetchAllAssignments(
      subjectTypes: ['kanji'],
    );

    final unlocked = <int>{};
    for (final a in assignments) {
      final data = a['data'] as Map<String, dynamic>;
      final sidRaw = data['subject_id'];
      if (sidRaw == null) continue;
      final sid = sidRaw is int ? sidRaw : int.tryParse(sidRaw.toString());
      if (sid == null) continue;
      final started = data['started_at'];
      final srs = data['srs_stage'];
      final isUnlocked = (started != null) || (srs != null && (srs as int) > 0);
      if (isUnlocked) unlocked.add(sid);
    }

    if (unlocked.isEmpty) return [];

    final subjects = await client.fetchSubjectsByIds(unlocked.toList());
    final items = subjects
        .where(
          (s) =>
              s['object'] == 'kanji' ||
              (s['data'] != null &&
                  (s['data'] as Map)['object_type'] == 'kanji'),
        )
        .map((s) => KanjiItem.fromSubject(s))
        .where((k) => k.characters.isNotEmpty && k.meanings.isNotEmpty)
        .toList();

    await saveKanji(items);
    return items;
  }
}