import 'dart:async';
import 'dart:typed_data';

import '../proto/messages.pb.dart';

/// Abstract decoder interface. Feeds raw frames in, emits envelopes out.
///
/// On native, the implementation runs in an isolate and batches envelopes.
/// On Web, the implementation decodes synchronously in [feed].
abstract class Decoder {
  /// Stream of decoded envelopes (or batches thereof, flattened to per-envelope).
  Stream<Envelope> get envelopes;

  /// Spin up any background machinery. No-op on the inline (Web) decoder.
  Future<void> start();

  /// Push a raw frame for decoding. Returns immediately.
  void feed(Uint8List frame);

  /// Tear down. Stops the isolate (on native) and closes the stream.
  Future<void> dispose();
}