import 'package:flutter/services.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';

/// `errSecDuplicateItem`: the iOS keychain refused to add an item that is
/// already there.
const int kErrSecDuplicateItem = -25299;

/// Whether [error] is the iOS keychain's "item already exists" failure.
/// flutter_secure_storage surfaces it as a PlatformException whose details
/// (and message) carry the OSStatus.
bool isKeychainDuplicateItem(Object error) {
  if (error is! PlatformException) return false;
  if (error.details == kErrSecDuplicateItem) return true;
  return error.message?.contains('$kErrSecDuplicateItem') ?? false;
}

extension KeychainWrite on FlutterSecureStorage {
  /// [write] that survives `errSecDuplicateItem`. The plugin's iOS write is
  /// check-then-add/update and not atomic: a concurrent write to the same key
  /// — or an existence check that itself failed (seen with the disk full) —
  /// ends in SecItemAdd on an existing item. The second attempt finds the
  /// item and updates it.
  Future<void> writeRetrying({
    required String key,
    required String value,
  }) async {
    try {
      await write(key: key, value: value);
    } on PlatformException catch (e) {
      if (!isKeychainDuplicateItem(e)) rethrow;
      await write(key: key, value: value);
    }
  }
}