import 'dart:io';

import 'package:drift/drift.dart';
import 'package:drift/native.dart';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';

part 'app_database.g.dart';

@DataClassName('DbNote')
class Notes extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text()();
  TextColumn get body => text()();
  DateTimeColumn get createdAt => dateTime()();
  DateTimeColumn get updatedAt => dateTime()();
  IntColumn get sortIndex => integer().named('sort_index')();
}

@DriftDatabase(tables: [Notes])
class AppDatabase extends _$AppDatabase {
  AppDatabase({required String encryptionKey}) : super(_openConnection(encryptionKey));

  @override
  int get schemaVersion => 1;

  Future<List<DbNote>> getAllNotes() {
    return (select(notes)..orderBy([
      (note) => OrderingTerm(expression: note.sortIndex),
    ])).get();
  }

  Future<int> insertNoteAtTop(NotesCompanion note) {
    return transaction(() async {
      await customStatement('UPDATE notes SET sort_index = sort_index + 1');
      return into(notes).insert(note.copyWith(sortIndex: const Value<int>(0)));
    });
  }

  Future<void> replaceAllNotes(List<NotesCompanion> noteList) {
    return transaction(() async {
      await delete(notes).go();

      for (final NotesCompanion note in noteList) {
        await into(notes).insert(note);
      }
    });
  }

  Future<void> updateNoteRow(DbNote note) {
    return update(notes).replace(note);
  }

  Future<void> deleteNoteAndShift({
    required int id,
    required int removedIndex,
  }) {
    return transaction(() async {
      await (delete(notes)..where((note) => note.id.equals(id))).go();
      await customStatement(
        'UPDATE notes SET sort_index = sort_index - 1 WHERE sort_index > ?',
        [removedIndex],
      );
    });
  }

  Future<void> moveNote({
    required int id,
    required int oldIndex,
    required int newIndex,
  }) {
    if (oldIndex == newIndex) {
      return Future<void>.value();
    }

    return transaction(() async {
      if (oldIndex < newIndex) {
        await customStatement(
          'UPDATE notes SET sort_index = sort_index - 1 WHERE sort_index > ? AND sort_index <= ?',
          [oldIndex, newIndex],
        );
      } else {
        await customStatement(
          'UPDATE notes SET sort_index = sort_index + 1 WHERE sort_index >= ? AND sort_index < ?',
          [newIndex, oldIndex],
        );
      }

      await customStatement(
        'UPDATE notes SET sort_index = ? WHERE id = ?',
        [newIndex, id],
      );
    });
  }
}

LazyDatabase _openConnection(String encryptionKey) {
  return LazyDatabase(() async {
    final Directory supportDir = await getApplicationSupportDirectory();
    final File file = File(p.join(supportDir.path, 'notes.sqlite'));

    return NativeDatabase(
      file,
      setup: (database) {
        final String escapedKey = encryptionKey.replaceAll("'", "''");

        // sqlite3mc can emulate SQLCipher file format for compatibility.
        database.execute("PRAGMA cipher = 'sqlcipher'");
        database.execute('PRAGMA legacy = 4');
        database.execute("PRAGMA key = '$escapedKey'");
      },
    );
  });
}