// Copyright (c) 2017, 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<ProcessSignal> watch()
/// Watch for process signals.
/// The following ProcessSignals can be listened to:
/// - ProcessSignal.sighup.
/// - ProcessSignal.sigint. Signal sent by e.g. CTRL-C.
/// - ProcessSignal.sigterm. Not available on Windows.
/// - ProcessSignal.sigusr1. Not available on Windows.
/// - ProcessSignal.sigusr2. Not available on Windows.
/// - ProcessSignal.sigwinch. Not available on Windows.
///
/// Other signals are disallowed, as they may be used by the VM.
///
/// A signal can be watched multiple times, from multiple isolates, where all
/// callbacks are invoked when signaled, in no specific order.
///
/// @description Checks that mention ProcessSignals can be watched.
/// @author ngl@unipro.ru

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

check(ProcessSignal signal) {
  String executable = Platform.resolvedExecutable;
  String eScript = Platform.script.toString();

  asyncStart();
  Process.start(executable, [
    ...Platform.executableArguments,
    eScript,
    signal.toString()
  ]).then((process) {
    process.stdin.close();
    process.stderr.drain();
    var output = "";
    process.stdout.transform(utf8.decoder).listen((str) {
      output += str;
      if (output == 'done\n') {
        process.kill(signal);
      }
    }, onDone: () {
      Expect.equals('done\n$signal\n', output);
    });
    process.exitCode.then((exitCode) {
      Expect.equals(0, exitCode);
      asyncEnd();
    });
  });
}

runMain() {
  if (!Platform.isWindows) {
    check(ProcessSignal.sighup);
    check(ProcessSignal.sigint);
    check(ProcessSignal.sigterm);
    check(ProcessSignal.sigusr1);
    check(ProcessSignal.sigusr2);
    check(ProcessSignal.sigwinch);
  }
}

runProcess(List<String> args) {
  // This process should die if it never receives a signal.
  var timeout = new Timer(new Duration(seconds: 5), () => exit(1));
  for (var arg in args) {
    var signal;
    switch (arg) {
      case 'SIGHUP':
        signal = ProcessSignal.sighup;
        break;
      case 'SIGINT':
        signal = ProcessSignal.sigint;
        break;
      case 'SIGTERM':
        signal = ProcessSignal.sigterm;
        break;
      case 'SIGUSR1':
        signal = ProcessSignal.sigusr1;
        break;
      case 'SIGUSR2':
        signal = ProcessSignal.sigusr2;
        break;
      case 'SIGWINCH':
        signal = ProcessSignal.sigwinch;
        break;
    }
    signal.watch().first.then((s) {
      if (signal != s) exit(1);
      if (signal.toString() != arg) exit(1);
      print(signal);
      exit(0);
    });
  }
  print("done");
}

main(List<String> args) {
  if (args.length > 0)
    runProcess(args);
  else {
    runMain();
  }
}