import 'dart:developer';
import 'dart:io';

import 'package:hydrated_bloc/hydrated_bloc.dart';

/// Opens the HydratedBloc box; a corrupt box is dropped and rebuilt, and if
/// even that fails the app runs on [InMemoryStorage] instead of never
/// reaching `runApp`.
Future<Storage> buildHydratedStorageWithFallback(String directoryPath) async {
  final directory = HydratedStorageDirectory(directoryPath);
  try {
    return await HydratedStorage.build(storageDirectory: directory);
  } catch (e, s) {
    log('HydratedStorage open failed, rebuilding: $e', stackTrace: s);
  }
  try {
    await _deleteHydratedBox(directoryPath);
    return await HydratedStorage.build(storageDirectory: directory);
  } catch (e, s) {
    log('HydratedStorage rebuild failed, using memory: $e', stackTrace: s);
    return InMemoryStorage();
  }
}

Future<void> _deleteHydratedBox(String directoryPath) async {
  final directory = Directory(directoryPath);
  if (!directory.existsSync()) return;
  await for (final entity in directory.list()) {
    final name = entity.uri.pathSegments.lastWhere((s) => s.isNotEmpty);
    if (entity is File && name.startsWith('hydrated_box')) {
      await entity.delete();
    }
  }
}

/// Non-persistent [Storage]; state lives for the session only.
class InMemoryStorage implements Storage {
  final Map<String, dynamic> _values = {};

  @override
  dynamic read(String key) => _values[key];

  @override
  Future<void> write(String key, dynamic value) async => _values[key] = value;

  @override
  Future<void> delete(String key) async => _values.remove(key);

  @override
  Future<void> clear() async => _values.clear();

  @override
  Future<void> close() async {}
}