// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// @assertion Stream<RawSocketEvent> take(int count)
/// Provides at most the first count data events of this stream.
///
/// Returns a stream that emits the same events that this stream would if
/// listened to at the same time, until either this stream ends or it has emitted
/// count data events, at which point the returned stream is done.
///
/// If this stream produces fewer than count data events before it's done, so
/// will the returned stream.
///
/// Starts listening to this stream when the returned stream is listened to and
/// stops listening when the first count data events have been received.
///
/// @description Checks that the events of this stream are forwarded to the
/// returned stream until count data events have been forwarded or this stream
/// ends. The returned stream is closed after receiving 'count' sent events.
/// If this stream produces fewer than count data events before it's done, this
/// stream will be returned.
/// @author ngl@unipro.ru

import "dart:io";
import "dart:async";
import "../../../Utils/expect.dart";

check(int n, List expected) {
  asyncStart();
  var address = InternetAddress.loopbackIPv4;
  RawDatagramSocket.bind(address, 0).then((producer) {
    RawDatagramSocket.bind(address, 0).then((receiver) {
      int sent = 0;
      int count = 0;
      List list = [];
      producer.send([sent++], address, receiver.port);
      producer.send([sent++], address, receiver.port);
      producer.send([sent++], address, receiver.port);
      producer.close();

      Stream s = receiver.take(n);
      s.listen((event) {
        list.add(event);
        receiver.receive();
        count++;
      }, onDone: () {
        Expect.listEquals(expected, list);
        Expect.equals(n > 4 ? 4 : n, count);
        asyncEnd();
      });

      new Timer(const Duration(milliseconds: 200), () {
        Expect.isNull(receiver.receive());
        receiver.close();
      });
    });
  });
}

main() {
  List expected = [
    RawSocketEvent.write,
    RawSocketEvent.read,
    RawSocketEvent.read,
    RawSocketEvent.closed
  ];
  check(0, []);
  check(1, expected.sublist(0, 1));
  check(2, expected.sublist(0, 2));
  check(3, expected.sublist(0, 3));
  check(4, expected);
  check(5, expected);
}