import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

import 'preferences_storage.dart';
import 'storage_keys.dart';

abstract interface class SecureKeyValueStorage {
  Future<String?> read(String key);
  Future<void> write(String key, String value);
  Future<void> delete(String key);
}

class FlutterSecureKeyValueStorage implements SecureKeyValueStorage {
  const FlutterSecureKeyValueStorage();

  static const _storage = FlutterSecureStorage();

  @override
  Future<String?> read(String key) => _storage.read(key: key);
  @override
  Future<void> write(String key, String value) =>
      _storage.write(key: key, value: value);
  @override
  Future<void> delete(String key) => _storage.delete(key: key);
}

/// Sensitive identity values stay behind one injectable storage boundary.
/// Legacy plaintext preferences are migrated only after a secure write works.
class SecureIdentityStorage {
  SecureIdentityStorage(
    this._preferences, {
    SecureKeyValueStorage secureStorage = const FlutterSecureKeyValueStorage(),
  }) : _storage = secureStorage;

  final PreferencesStorage _preferences;
  final SecureKeyValueStorage _storage;

  Future<String?> restoreAccessToken() async {
    final legacyPreferences = _normalized(
      _preferences.getString(storageLegacyAccessToken),
    );
    final hasInstallSession = _preferences.getBool(storageAuthSessionActive);

    // A plaintext token proves that this installation predates secure storage
    // migration. A Keychain token by itself does not: iOS may retain it after
    // uninstall while SharedPreferences (including this marker) is reset.
    if (!hasInstallSession && legacyPreferences == null) {
      await _deleteAllAuthCredentials();
      await _preferences.remove(storageAuthSessionActive);
      return null;
    }

    final current = _normalized(await _storage.read(secureAccessToken));
    final legacySecure = current == null
        ? _normalized(await _storage.read(secureLegacyJwtToken))
        : null;
    final token = current ?? legacyPreferences ?? legacySecure;
    if (current == null && token != null) {
      await _storage.write(secureAccessToken, token);
    }
    await _storage.delete(secureLegacyJwtToken);
    await _preferences.remove(storageLegacyAccessToken);
    if (token == null) {
      await _preferences.remove(storageAuthSessionActive);
    } else {
      await _preferences.setBool(storageAuthSessionActive, true);
    }
    return token;
  }

  Future<String?> readJwt() async {
    if (!_preferences.getBool(storageAuthSessionActive) ||
        _preferences.containsKey(storageLegacyAccessToken)) {
      return restoreAccessToken();
    }
    final token = _normalized(await _storage.read(secureAccessToken));
    if (token == null) await _preferences.remove(storageAuthSessionActive);
    return token;
  }

  Future<void> saveJwt(String token) async {
    final normalized = _normalized(token);
    if (normalized == null) {
      throw ArgumentError.value(token, 'token', 'must not be empty');
    }
    await _storage.write(secureAccessToken, normalized);
    await _storage.delete(secureLegacyJwtToken);
    await _preferences.remove(storageLegacyAccessToken);
    await _preferences.setBool(storageAuthSessionActive, true);
  }

  Future<void> clearJwt() async {
    await _deleteAllAuthCredentials();
    await _preferences.remove(storageLegacyAccessToken);
    await _preferences.remove(storageAuthSessionActive);
  }

  Future<void> clearSessionCredentials() async {
    await clearJwt();
    await _storage.delete(secureMallCredential);
    await _storage.delete(secureRefreshToken);
  }

  Future<void> clearAccountCredentials() async {
    await clearSessionCredentials();
    await _storage.delete(secureBiometricCredential);
  }

  Future<String?> readDeviceId() => _storage.read(secureDeviceId);

  Future<void> saveDeviceId(String deviceId) =>
      _storage.write(secureDeviceId, deviceId);

  Future<void> _deleteAllAuthCredentials() async {
    await _storage.delete(secureAccessToken);
    await _storage.delete(secureLegacyJwtToken);
  }
}

final secureIdentityStorageProvider = Provider<SecureIdentityStorage>(
  (ref) => SecureIdentityStorage(ref.watch(preferencesStorageProvider)),
);

/// Process-memory session snapshot. Interceptors read this synchronously;
/// secure storage is touched only when a session starts, restores, or ends.
class AuthSessionStorage {
  AuthSessionStorage(this._identityStorage);

  final SecureIdentityStorage _identityStorage;
  String? _accessToken;
  int _generation = 0;
  Future<String?>? _restoreFuture;
  Future<void> _operationTail = Future<void>.value();

  String? get accessToken => _accessToken;
  int get generation => _generation;

  Future<String?> restore() => _restoreFuture ??= _serialize(_restore);

  Future<String?> _restore() async {
    _accessToken = await _identityStorage.restoreAccessToken();
    _generation++;
    return _accessToken;
  }

  Future<void> save(String token) async {
    await _serialize(() async {
      await _identityStorage.saveJwt(token);
      _accessToken = token.trim();
      _generation++;
      _restoreFuture = Future<String?>.value(_accessToken);
    });
  }

  Future<void> clear({bool accountDeleted = false}) async {
    await _serialize(() async {
      if (accountDeleted) {
        await _identityStorage.clearAccountCredentials();
      } else {
        await _identityStorage.clearSessionCredentials();
      }
      _accessToken = null;
      _generation++;
      _restoreFuture = Future<String?>.value();
    });
  }

  Future<T> _serialize<T>(Future<T> Function() operation) {
    final result = _operationTail.then((_) => operation());
    _operationTail = result.then<void>(
      (_) {},
      onError: (Object _, StackTrace _) {},
    );
    return result;
  }
}

final authSessionStorageProvider = Provider<AuthSessionStorage>(
  (ref) => AuthSessionStorage(ref.watch(secureIdentityStorageProvider)),
);

String? _normalized(String? value) {
  final normalized = value?.trim() ?? '';
  return normalized.isEmpty ? null : normalized;
}