Repository Pattern

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// Domain layer – abstract
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abstract class UserRepository {
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  Future<Either<Failure, User>> getUser(String id);
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  Future<Either<Failure, List<User>>> getUsers();
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}
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// Data layer – implementation
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class UserRepositoryImpl implements UserRepository {
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  final UserRemoteDataSource remoteDataSource;
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  final UserLocalDataSource localDataSource;
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  final NetworkInfo networkInfo;
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  const UserRepositoryImpl({
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    required this.remoteDataSource,
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    required this.localDataSource,
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    required this.networkInfo,
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  });
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  @override
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  Future<Either<Failure, User>> getUser(String id) async {
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    if (await networkInfo.isConnected) {
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      try {
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        final user = await remoteDataSource.getUser(id);
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        await localDataSource.cacheUser(user);
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        return Right(user.toDomain());
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      } on ServerException catch (e) {
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        return Left(ServerFailure(e.message));
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      }
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    } else {
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      try {
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        final user = await localDataSource.getCachedUser(id);
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        return Right(user.toDomain());
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      } on CacheException {
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        return const Left(CacheFailure());
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      }
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    }
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  }
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  @override
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  Future<Either<Failure, List<User>>> getUsers() async {
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    // similar pattern...
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    throw UnimplementedError();
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  }
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}