// 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<E> asyncExpand<E>(Stream<E> convert(T event))
/// Transforms each element into a sequence of asynchronous events.
///
/// Returns a new stream and for each event of this stream, do the following:
///
/// - If the event is an error event or a done event, it is emitted directly by
///   the returned stream.
/// - Otherwise it is an element. Then the convert function is called with the
///   element as argument to produce a convert-stream for the element.
/// - If that call throws, the error is emitted on the returned stream.
/// - . . .
/// - Otherwise, this stream is paused and convert-stream is listened to. Every
///   data and error event of the convert-stream is emitted on the returned
///   stream in the order it is produced. When the convert-stream ends, this
///   stream is resumed.
///
/// @description Checks that the convert function is called with the element as
/// argument to produce a convert-stream for the element, and a convert-stream
/// is emitted on the returned stream in the order it is produced.
/// @author ngl@unipro.ru

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

var localhost = InternetAddress.loopbackIPv4;

Future<List<RawSocketEvent>> check(convert) async {
  RawDatagramSocket producer = await RawDatagramSocket.bind(localhost, 0);
  RawDatagramSocket receiver = await RawDatagramSocket.bind(localhost, 0);
  List<List<int>> toSend = [[0, 1, 2, 3], [1, 2, 3], [2, 3], [3]];
  List<RawSocketEvent> received = [];
  Completer<List<RawSocketEvent>> completer =
      new Completer<List<RawSocketEvent>>();
  Future<List<RawSocketEvent>> f = completer.future;

  bool wasSent = await sendDatagram(producer, toSend, localhost, receiver.port);
  Expect.isTrue(wasSent, "No datagram was sent");

  receiver.close();

  Stream s = receiver.asyncExpand(convert);
  s.listen((value) {
    received.add(value);
    Expect.equals(RawSocketEvent.closed, value);
  }).onDone(() {
    if (!completer.isCompleted) {
      completer.complete(received);
    }
  });
  return f;
}

main() async {
  int attempts4asyncExpand = 5;

  toCheck(convert, List expected) async {
    int expectedLen = expected.length;
    for (int i = 0; i < attempts4asyncExpand; i++) {
      List list = await check(convert);
      int listLen = list.length;
      if (listLen == 0) {
        continue;
      }
      if (listLen == expectedLen) {
        Expect.listEquals(expected, list);
        break;
      }
      if (listLen > expectedLen) {
        Expect.fail("$listLen elements found instead of $expectedLen.");
      }
      if (i == attempts4asyncExpand - 1) {
        print('$listLen elements found. Look like test failed.');
      }
    }
  }

  toCheck((e) => new Stream.fromIterable([e]), [RawSocketEvent.closed]);
  toCheck((e) => new Stream.fromIterable([e, e]),
      [RawSocketEvent.closed, RawSocketEvent.closed]);
}