import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'database_constants.dart';

class DatabaseHelper {
  static final DatabaseHelper _instance = DatabaseHelper._internal();
  static Database? _db;

  factory DatabaseHelper() {
    return _instance;
  }

  DatabaseHelper._internal();

  Future<Database> get db async {
    if (_db != null) return _db!;
    _db = await _openDb();
    return _db!;
  }

  Future<void> close() async {
    if (_db != null) {
      await _db!.close();
      _db = null;
    }
  }

  Future<Database> _openDb() async {
    final dir = await getApplicationDocumentsDirectory();
    final path = join(dir.path, 'wanikani_srs.db');

    return openDatabase(
      path,
      version: 8,
      onCreate: (db, version) async {
        await db.execute(
          '''CREATE TABLE ${DbConstants.kanjiTable} (${DbConstants.idColumn} INTEGER PRIMARY KEY, ${DbConstants.levelColumn} INTEGER, ${DbConstants.charactersColumn} TEXT, ${DbConstants.meaningsColumn} TEXT, ${DbConstants.onyomiColumn} TEXT, ${DbConstants.kunyomiColumn} TEXT)''',
        );
        await db.execute(
          '''CREATE TABLE ${DbConstants.settingsTable} (${DbConstants.keyColumn} TEXT PRIMARY KEY, ${DbConstants.valueColumn} TEXT)''',
        );
        await db.execute(
          '''CREATE TABLE ${DbConstants.srsItemsTable} (${DbConstants.kanjiIdColumn} INTEGER, ${DbConstants.quizModeColumn} TEXT, ${DbConstants.readingTypeColumn} TEXT, ${DbConstants.srsStageColumn} INTEGER, ${DbConstants.lastAskedColumn} TEXT, ${DbConstants.disabledColumn} INTEGER DEFAULT 0, PRIMARY KEY (${DbConstants.kanjiIdColumn}, ${DbConstants.quizModeColumn}, ${DbConstants.readingTypeColumn}))''',
        );
        await db.execute(
          '''CREATE TABLE ${DbConstants.vocabularyTable} (${DbConstants.idColumn} INTEGER PRIMARY KEY, ${DbConstants.levelColumn} INTEGER, ${DbConstants.charactersColumn} TEXT, ${DbConstants.meaningsColumn} TEXT, ${DbConstants.readingsColumn} TEXT, ${DbConstants.pronunciationAudiosColumn} TEXT)''',
        );
        await db.execute(
          '''CREATE TABLE ${DbConstants.srsVocabItemsTable} (${DbConstants.vocabIdColumn} INTEGER, ${DbConstants.quizModeColumn} TEXT, ${DbConstants.srsStageColumn} INTEGER, ${DbConstants.lastAskedColumn} TEXT, ${DbConstants.disabledColumn} INTEGER DEFAULT 0, PRIMARY KEY (${DbConstants.vocabIdColumn}, ${DbConstants.quizModeColumn}))''',
        );
      },
      onUpgrade: (db, oldVersion, newVersion) async {
        if (oldVersion < 8) {
          await db.execute('ALTER TABLE ${DbConstants.srsItemsTable} ADD COLUMN ${DbConstants.disabledColumn} INTEGER DEFAULT 0');
          await db.execute('ALTER TABLE ${DbConstants.srsVocabItemsTable} ADD COLUMN ${DbConstants.disabledColumn} INTEGER DEFAULT 0');
        }
      },
    );
  }
}