packages/flutter_tools/lib/src/android/android_device.dart

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:path/path.dart' as path;

import '../android/android_sdk.dart';
import '../application_package.dart';
import '../base/os.dart';
import '../base/process.dart';
import '../build_info.dart';
import '../dart/package_map.dart';
import '../device.dart';
import '../flx.dart' as flx;
import '../globals.dart';
import '../toolchain.dart';
import '../vmservice.dart';
import '../protocol_discovery.dart';
import 'adb.dart';
import 'android.dart';
import 'android_sdk.dart';

const String _defaultAdbPath = 'adb';

// Path where the FLX bundle will be copied on the device.
const String _deviceBundlePath = '/data/local/tmp/dev.flx';

// Path where the snapshot will be copied on the device.
const String _deviceSnapshotPath = '/data/local/tmp/dev_snapshot.bin';

class AndroidDevices extends PollingDeviceDiscovery {
  AndroidDevices() : super('AndroidDevices');

  @override
  bool get supportsPlatform => true;

  @override
  List<Device> pollingGetDevices() => getAdbDevices();
}

class AndroidDevice extends Device {
  AndroidDevice(
    String id, {
    this.productID,
    this.modelID,
    this.deviceCodeName
  }) : super(id);

  final String productID;
  final String modelID;
  final String deviceCodeName;

  Map<String, String> _properties;
  bool _isLocalEmulator;
  TargetPlatform _platform;

  String _getProperty(String name) {
    if (_properties == null) {
      _properties = <String, String>{};

      List<String> propCommand = adbCommandForDevice(<String>['shell', 'getprop']);
      printTrace(propCommand.join(' '));

      try {
        // We pass an encoding of LATIN1 so that we don't try and interpret the
        // `adb shell getprop` result as UTF8.
        ProcessResult result = Process.runSync(
          propCommand.first,
          propCommand.sublist(1),
          stdoutEncoding: LATIN1
        );
        if (result.exitCode == 0) {
          _properties = parseAdbDeviceProperties(result.stdout);
        } else {
          printError('Error retrieving device properties for $name.');
        }
      } catch (error) {
        printError('Error retrieving device properties for $name: $error');
      }
    }

    return _properties[name];
  }

  @override
  bool get isLocalEmulator {
    if (_isLocalEmulator == null) {
      String characteristics = _getProperty('ro.build.characteristics');
      _isLocalEmulator = characteristics != null && characteristics.contains('emulator');
    }
    return _isLocalEmulator;
  }

  @override
  TargetPlatform get platform {
    if (_platform == null) {
      // http://developer.android.com/ndk/guides/abis.html (x86, armeabi-v7a, ...)
      switch (_getProperty('ro.product.cpu.abi')) {
        case 'x86_64':
          _platform = TargetPlatform.android_x64;
          break;
        case 'x86':
          _platform = TargetPlatform.android_x86;
          break;
        default:
          _platform = TargetPlatform.android_arm;
          break;
      }
    }

    return _platform;
  }

  @override
  String get sdkNameAndVersion => 'Android $_sdkVersion (API $_apiVersion)';

  String get _sdkVersion => _getProperty('ro.build.version.release');

  String get _apiVersion => _getProperty('ro.build.version.sdk');

  _AdbLogReader _logReader;
  _AndroidDevicePortForwarder _portForwarder;

  List<String> adbCommandForDevice(List<String> args) {
    return <String>[getAdbPath(androidSdk), '-s', id]..addAll(args);
  }

  bool _isValidAdbVersion(String adbVersion) {
    // Sample output: 'Android Debug Bridge version 1.0.31'
    Match versionFields = new RegExp(r'(\d+)\.(\d+)\.(\d+)').firstMatch(adbVersion);
    if (versionFields != null) {
      int majorVersion = int.parse(versionFields[1]);
      int minorVersion = int.parse(versionFields[2]);
      int patchVersion = int.parse(versionFields[3]);
      if (majorVersion > 1) {
        return true;
      }
      if (majorVersion == 1 && minorVersion > 0) {
        return true;
      }
      if (majorVersion == 1 && minorVersion == 0 && patchVersion >= 32) {
        return true;
      }
      return false;
    }
    printError(
        'Unrecognized adb version string $adbVersion. Skipping version check.');
    return true;
  }

  bool _checkForSupportedAdbVersion() {
    if (androidSdk == null)
      return false;

    try {
      String adbVersion = runCheckedSync(<String>[getAdbPath(androidSdk), 'version']);
      if (_isValidAdbVersion(adbVersion))
        return true;
      printError('The ADB at "${getAdbPath(androidSdk)}" is too old; please install version 1.0.32 or later.');
    } catch (error, trace) {
      printError('Error running ADB: $error', trace);
    }

    return false;
  }

  bool _checkForSupportedAndroidVersion() {
    try {
      // If the server is automatically restarted, then we get irrelevant
      // output lines like this, which we want to ignore:
      //   adb server is out of date.  killing..
      //   * daemon started successfully *
      runCheckedSync(<String>[getAdbPath(androidSdk), 'start-server']);

      // Sample output: '22'
      String sdkVersion = _getProperty('ro.build.version.sdk');

      int sdkVersionParsed = int.parse(sdkVersion, onError: (String source) => null);
      if (sdkVersionParsed == null) {
        printError('Unexpected response from getprop: "$sdkVersion"');
        return false;
      }

      if (sdkVersionParsed < minApiLevel) {
        printError(
          'The Android version ($sdkVersion) on the target device is too old. Please '
          'use a $minVersionName (version $minApiLevel / $minVersionText) device or later.');
        return false;
      }

      return true;
    } catch (e) {
      printError('Unexpected failure from adb: $e');
      return false;
    }
  }

  String _getDeviceSha1Path(ApplicationPackage app) {
    return '/data/local/tmp/sky.${app.id}.sha1';
  }

  String _getDeviceApkSha1(ApplicationPackage app) {
    return runCheckedSync(adbCommandForDevice(<String>['shell', 'cat', _getDeviceSha1Path(app)]));
  }

  String _getSourceSha1(ApplicationPackage app) {
    AndroidApk apk = app;
    File shaFile = new File('${apk.apkPath}.sha1');
    return shaFile.existsSync() ? shaFile.readAsStringSync() : '';
  }

  @override
  String get name => modelID;

  @override
  bool isAppInstalled(ApplicationPackage app) {
    // This call takes 400ms - 600ms.
    String listOut = runCheckedSync(adbCommandForDevice(<String>['shell', 'pm', 'list', 'packages', app.id]));
    if (!LineSplitter.split(listOut).contains("package:${app.id}"))
      return false;

    // Check the application SHA.
    return _getDeviceApkSha1(app) == _getSourceSha1(app);
  }

  @override
  bool installApp(ApplicationPackage app) {
    AndroidApk apk = app;
    if (!FileSystemEntity.isFileSync(apk.apkPath)) {
      printError('"${apk.apkPath}" does not exist.');
      return false;
    }

    if (!_checkForSupportedAdbVersion() || !_checkForSupportedAndroidVersion())
      return false;

    String installOut = runCheckedSync(adbCommandForDevice(<String>['install', '-r', apk.apkPath]));
    RegExp failureExp = new RegExp(r'^Failure.*$', multiLine: true);
    String failure = failureExp.stringMatch(installOut);
    if (failure != null) {
      printError('Package install error: $failure');
      return false;
    }

    runCheckedSync(adbCommandForDevice(<String>['shell', 'echo', '-n', _getSourceSha1(app), '>', _getDeviceSha1Path(app)]));
    return true;
  }

  @override
  bool uninstallApp(ApplicationPackage app) {
    if (!_checkForSupportedAdbVersion() || !_checkForSupportedAndroidVersion())
      return false;

    String uninstallOut = runCheckedSync(adbCommandForDevice(<String>['uninstall', app.id]));
    RegExp failureExp = new RegExp(r'^Failure.*$', multiLine: true);
    String failure = failureExp.stringMatch(uninstallOut);
    if (failure != null) {
      printError('Package uninstall error: $failure');
      return false;
    }

    return true;
  }

  Future<Null> _forwardPort(String service, int devicePort, int port) async {
    try {
      // Set up port forwarding for observatory.
      port = await portForwarder.forward(devicePort, hostPort: port);
      printStatus('$service listening on http://127.0.0.1:$port');
    } catch (e) {
      printError('Unable to forward port $port: $e');
    }
  }

  Future<LaunchResult> startBundle(AndroidApk apk, String bundlePath, {
    bool traceStartup: false,
    String route,
    DebuggingOptions options
  }) async {
    printTrace('$this startBundle');

    if (bundlePath != null) {
      if (!FileSystemEntity.isFileSync(bundlePath)) {
        printError('Cannot find $bundlePath');
        return new LaunchResult.failed();
      }

      runCheckedSync(
          adbCommandForDevice(<String>['push', bundlePath, _deviceBundlePath]));
    }

    ProtocolDiscovery observatoryDiscovery;
    ProtocolDiscovery diagnosticDiscovery;

    if (options.debuggingEnabled) {
      observatoryDiscovery = new ProtocolDiscovery(logReader, ProtocolDiscovery.kObservatoryService);
      diagnosticDiscovery = new ProtocolDiscovery(logReader, ProtocolDiscovery.kDiagnosticService);
    }

    List<String> cmd;

    if (bundlePath != null) {
      // Specify in the RUN intent the path to the local bundle pushed.
      cmd = adbCommandForDevice(<String>[
        'shell', 'am', 'start',
        '-a', 'android.intent.action.RUN',
        '-d', _deviceBundlePath,
        '-f', '0x20000000',  // FLAG_ACTIVITY_SINGLE_TOP
        '--ez', 'enable-background-compilation', 'true',
      ]);
    } else {
      cmd = adbCommandForDevice(<String>[
        'shell', 'am', 'start',
        '-a', 'android.intent.action.RUN',
        '-f', '0x20000000',  // FLAG_ACTIVITY_SINGLE_TOP
        '--ez', 'enable-background-compilation', 'true',
      ]);
    }

    if (traceStartup)
      cmd.addAll(<String>['--ez', 'trace-startup', 'true']);
    if (route != null)
      cmd.addAll(<String>['--es', 'route', route]);
    if (options.debuggingEnabled) {
      if (options.buildMode == BuildMode.debug)
        cmd.addAll(<String>['--ez', 'enable-checked-mode', 'true']);
      if (options.startPaused)
        cmd.addAll(<String>['--ez', 'start-paused', 'true']);
    }
    cmd.add(apk.launchActivity);
    String result = runCheckedSync(cmd);
    // This invocation returns 0 even when it fails.
    if (result.contains('Error: ')) {
      printError(result.trim());
      return new LaunchResult.failed();
    }

    if (!options.debuggingEnabled) {
      return new LaunchResult.succeeded();
    } else {
      // Wait for the service protocol port here. This will complete once the
      // device has printed "Observatory is listening on...".
      printTrace('Waiting for observatory port to be available...');

      try {
        int observatoryDevicePort, diagnosticDevicePort;

        if (options.buildMode == BuildMode.debug) {
          Future<List<int>> scrapeServicePorts = Future.wait(
            <Future<int>>[observatoryDiscovery.nextPort(), diagnosticDiscovery.nextPort()]
          );
          List<int> devicePorts = await scrapeServicePorts.timeout(new Duration(seconds: 20));
          observatoryDevicePort = devicePorts[0];
          diagnosticDevicePort = devicePorts[1];
        } else {
          observatoryDevicePort = await observatoryDiscovery.nextPort().timeout(new Duration(seconds: 20));
        }

        printTrace('observatory port = $observatoryDevicePort');
        int observatoryLocalPort = await options.findBestObservatoryPort();
        // TODO(devoncarew): Remember the forwarding information (so we can later remove the
        // port forwarding).
        await _forwardPort(ProtocolDiscovery.kObservatoryService, observatoryDevicePort, observatoryLocalPort);

        int diagnosticLocalPort;
        if (diagnosticDevicePort != null) {
          printTrace('diagnostic port = $diagnosticDevicePort');
          diagnosticLocalPort = await options.findBestDiagnosticPort();
          await _forwardPort(ProtocolDiscovery.kDiagnosticService, diagnosticDevicePort, diagnosticLocalPort);
        }

        return new LaunchResult.succeeded(
          observatoryPort: observatoryLocalPort,
          diagnosticPort: diagnosticLocalPort
        );
      } catch (error) {
        if (error is TimeoutException)
          printError('Timed out while waiting for a debug connection.');
        else
          printError('Error waiting for a debug connection: $error');
        return new LaunchResult.failed();
      } finally {
        observatoryDiscovery.cancel();
        diagnosticDiscovery.cancel();
      }
    }
  }

  @override
  Future<LaunchResult> startApp(
    ApplicationPackage package,
    BuildMode mode, {
    String mainPath,
    String route,
    DebuggingOptions debuggingOptions,
    Map<String, dynamic> platformArgs,
    bool prebuiltApplication: false
  }) async {
    if (!_checkForSupportedAdbVersion() || !_checkForSupportedAndroidVersion())
      return new LaunchResult.failed();

    String localBundlePath;

    if (!prebuiltApplication) {
      localBundlePath = await flx.buildFlx(
        mainPath: mainPath,
        precompiledSnapshot: isAotBuildMode(debuggingOptions.buildMode),
        includeRobotoFonts: false
      );
      if (localBundlePath == null)
        return new LaunchResult.failed();
    }

    printTrace('Starting bundle for $this.');

    return startBundle(
      package,
      localBundlePath,
      traceStartup: platformArgs['trace-startup'] ?? false,
      route: route,
      options: debuggingOptions
    );
  }

  @override
  bool get supportsHotMode => true;

  @override
  Future<bool> runFromFile(ApplicationPackage package,
                           String scriptUri,
                           String packagesUri) async {
    AndroidApk apk = package;
    List<String> cmd = adbCommandForDevice(<String>[
      'shell', 'am', 'start',
      '-a', 'android.intent.action.RUN',
      '-d', _deviceBundlePath,
      '-f', '0x20000000',  // FLAG_ACTIVITY_SINGLE_TOP
    ]);
    cmd.addAll(<String>['--es', 'file', scriptUri]);
    cmd.addAll(<String>['--es', 'packages', packagesUri]);
    cmd.add(apk.launchActivity);
    String result = runCheckedSync(cmd);
    if (result.contains('Error: ')) {
      printError(result.trim());
      return false;
    }
    return true;
  }

  @override
  bool get supportsRestart => true;

  @override
  Future<bool> restartApp(
    ApplicationPackage package,
    LaunchResult result, {
    String mainPath,
    VMService observatory,
    bool prebuiltApplication: false
  }) async {
    Directory tempDir = await Directory.systemTemp.createTemp('flutter_tools');

    if (prebuiltApplication) {
      return false;
    }

    try {
      String snapshotPath = path.join(tempDir.path, 'snapshot_blob.bin');
      int result = await flx.createSnapshot(
        snapshotterPath: tools.getHostToolPath(HostTool.SkySnapshot),
        mainPath: mainPath,
        snapshotPath: snapshotPath,
        packages: path.absolute(PackageMap.globalPackagesPath),
     );

      if (result != 0) {
        printError('Failed to run the Flutter compiler; exit code: $result');
        return false;
      }

      AndroidApk apk = package;
      String androidActivity = apk.launchActivity;
      bool success = await refreshSnapshot(androidActivity, snapshotPath);

      if (!success) {
        printError('Error refreshing snapshot on $this.');
        return false;
      }

      return true;
    } finally {
      tempDir.deleteSync(recursive: true);
    }
  }

  @override
  Future<bool> stopApp(ApplicationPackage app) {
    List<String> command = adbCommandForDevice(<String>['shell', 'am', 'force-stop', app.id]);
    return runCommandAndStreamOutput(command).then((int exitCode) => exitCode == 0);
  }

  @override
  void clearLogs() {
    runSync(adbCommandForDevice(<String>['logcat', '-c']));
  }

  @override
  DeviceLogReader get logReader {
    if (_logReader == null)
      _logReader = new _AdbLogReader(this);
    return _logReader;
  }

  @override
  DevicePortForwarder get portForwarder {
    if (_portForwarder == null)
      _portForwarder = new _AndroidDevicePortForwarder(this);

    return _portForwarder;
  }

  /// Return the most recent timestamp in the Android log or `null` if there is
  /// no available timestamp. The format can be passed to logcat's -T option.
  String get lastLogcatTimestamp {
    String output = runCheckedSync(adbCommandForDevice(<String>[
      'logcat', '-v', 'time', '-t', '1'
    ]));

    RegExp timeRegExp = new RegExp(r'^\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3}', multiLine: true);
    Match timeMatch = timeRegExp.firstMatch(output);
    return timeMatch?.group(0);
  }

  @override
  bool isSupported() => true;

  Future<bool> refreshSnapshot(String activity, String snapshotPath) async {
    if (!FileSystemEntity.isFileSync(snapshotPath)) {
      printError('Cannot find $snapshotPath');
      return false;
    }

    RunResult result = await runAsync(
      adbCommandForDevice(<String>['push', snapshotPath, _deviceSnapshotPath])
    );
    if (result.exitCode != 0) {
      printStatus(result.toString());
      return false;
    }

    List<String> cmd = adbCommandForDevice(<String>[
      'shell', 'am', 'start',
      '-a', 'android.intent.action.RUN',
      '-d', _deviceBundlePath,
      '-f', '0x20000000',  // FLAG_ACTIVITY_SINGLE_TOP
      '--es', 'snapshot', _deviceSnapshotPath,
      activity,
    ]);
    result = await runAsync(cmd);
    if (result.exitCode != 0) {
      printStatus(result.toString());
      return false;
    }

    final RegExp errorRegExp = new RegExp(r'^Error: .*$', multiLine: true);
    Match errorMatch = errorRegExp.firstMatch(result.processResult.stdout);
    if (errorMatch != null) {
      printError(errorMatch.group(0));
      return false;
    }

    return true;
  }

  @override
  bool get supportsScreenshot => true;

  @override
  Future<bool> takeScreenshot(File outputFile) {
    const String remotePath = '/data/local/tmp/flutter_screenshot.png';

    runCheckedSync(adbCommandForDevice(<String>['shell', 'screencap', '-p', remotePath]));
    runCheckedSync(adbCommandForDevice(<String>['pull', remotePath, outputFile.path]));
    runCheckedSync(adbCommandForDevice(<String>['shell', 'rm', remotePath]));

    return new Future<bool>.value(true);
  }

  @override
  Future<List<DiscoveredApp>> discoverApps() {
    RegExp discoverExp = new RegExp(r'DISCOVER: (.*)');
    List<DiscoveredApp> result = <DiscoveredApp>[];
    StreamSubscription<String> logs = logReader.logLines.listen((String line) {
      Match match = discoverExp.firstMatch(line);
      if (match != null) {
        Map<String, dynamic> app = JSON.decode(match.group(1));
        result.add(new DiscoveredApp(app['id'], app['observatoryPort']));
      }
    });

    runCheckedSync(adbCommandForDevice(<String>[
      'shell', 'am', 'broadcast', '-a', 'io.flutter.view.DISCOVER'
    ]));

    return new Future<List<DiscoveredApp>>.delayed(new Duration(seconds: 1), () {
      logs.cancel();
      return result;
    });
  }
}

Map<String, String> parseAdbDeviceProperties(String str) {
  Map<String, String> properties = <String, String>{};
  final RegExp propertyExp = new RegExp(r'\[(.*?)\]: \[(.*?)\]');
  for (Match match in propertyExp.allMatches(str))
    properties[match.group(1)] = match.group(2);
  return properties;
}

// 015d172c98400a03       device usb:340787200X product:nakasi model:Nexus_7 device:grouper
final RegExp _kDeviceRegex = new RegExp(r'^(\S+)\s+(\S+)(.*)');

/// Return the list of connected ADB devices.
///
/// [mockAdbOutput] is public for testing.
List<AndroidDevice> getAdbDevices({ String mockAdbOutput }) {
  List<AndroidDevice> devices = <AndroidDevice>[];
  List<String> output;

  if (mockAdbOutput == null) {
    String adbPath = getAdbPath(androidSdk);
    if (adbPath == null)
      return <AndroidDevice>[];
    output = runSync(<String>[adbPath, 'devices', '-l']).trim().split('\n');
  } else {
    output = mockAdbOutput.trim().split('\n');
  }

  for (String line in output) {
    // Skip lines like: * daemon started successfully *
    if (line.startsWith('* daemon '))
      continue;

    if (line.startsWith('List of devices'))
      continue;

    if (_kDeviceRegex.hasMatch(line)) {
      Match match = _kDeviceRegex.firstMatch(line);

      String deviceID = match[1];
      String deviceState = match[2];
      String rest = match[3];

      Map<String, String> info = <String, String>{};
      if (rest != null && rest.isNotEmpty) {
        rest = rest.trim();
        for (String data in rest.split(' ')) {
          if (data.contains(':')) {
            List<String> fields = data.split(':');
            info[fields[0]] = fields[1];
          }
        }
      }

      if (info['model'] != null)
        info['model'] = cleanAdbDeviceName(info['model']);

      if (deviceState == 'unauthorized') {
        printError(
          'Device $deviceID is not authorized.\n'
          'You might need to check your device for an authorization dialog.'
        );
      } else if (deviceState == 'offline') {
        printError('Device $deviceID is offline.');
      } else {
        devices.add(new AndroidDevice(
          deviceID,
          productID: info['product'],
          modelID: info['model'] ?? deviceID,
          deviceCodeName: info['device']
        ));
      }
    } else {
      printError(
        'Unexpected failure parsing device information from adb output:\n'
        '$line\n'
        'Please report a bug at https://github.com/flutter/flutter/issues/new');
    }
  }

  return devices;
}

/// A log reader that logs from `adb logcat`.
class _AdbLogReader extends DeviceLogReader {
  _AdbLogReader(this.device) {
    _linesController = new StreamController<String>.broadcast(
      onListen: _start,
      onCancel: _stop
    );
  }

  final AndroidDevice device;

  bool _lastWasFiltered = false;

  StreamController<String> _linesController;
  Process _process;

  @override
  Stream<String> get logLines => _linesController.stream;

  @override
  String get name => device.name;

  void _start() {
    // Start the adb logcat process.
    List<String> args = <String>['logcat', '-v', 'tag'];
    String lastTimestamp = device.lastLogcatTimestamp;
    if (lastTimestamp != null) {
      bool supportsLastTimestamp = false;

      // Check to see if this copy of adb supports -T.
      try {
        // "logcat: invalid option -- T", "Unrecognized Option"
        // logcat -g will finish immediately; it will print an error to stdout if -T isn't supported.
        String result = runSync(device.adbCommandForDevice(<String>['logcat', '-g', '-T', lastTimestamp]));
        supportsLastTimestamp = !result.contains('logcat: invalid option') && !result.contains('Unrecognized Option');
      } catch (_) { }

      if (supportsLastTimestamp)
        args.addAll(<String>['-T', lastTimestamp]);
    }
    runCommand(device.adbCommandForDevice(args)).then((Process process) {
      _process = process;
      _process.stdout.transform(UTF8.decoder).transform(const LineSplitter()).listen(_onLine);
      _process.stderr.transform(UTF8.decoder).transform(const LineSplitter()).listen(_onLine);

      _process.exitCode.then((int code) {
        if (_linesController.hasListener)
          _linesController.close();
      });
    });
  }

  // 'W/ActivityManager: '
  static final RegExp _logFormat = new RegExp(r'^[VDIWEF]\/[^:]+:\s+');

  static final List<RegExp> _whitelistedTags = <RegExp>[
    new RegExp(r'^[VDIWEF]\/flutter[^:]*:\s+', caseSensitive: false),
    new RegExp(r'^[IE]\/DartVM[^:]*:\s+'),
    new RegExp(r'^[WEF]\/AndroidRuntime:\s+'),
    new RegExp(r'^[WEF]\/ActivityManager:\s+'),
    new RegExp(r'^[WEF]\/System\.err:\s+'),
    new RegExp(r'^[F]\/[\S^:]+:\s+')
  ];

  void _onLine(String line) {
    if (_logFormat.hasMatch(line)) {
      // Filter out some noisy ActivityManager notifications.
      if (line.startsWith('W/ActivityManager: getRunningAppProcesses'))
        return;

      // Filter on approved names and levels.
      for (RegExp regex in _whitelistedTags) {
        if (regex.hasMatch(line)) {
          _lastWasFiltered = false;
          _linesController.add(line);
          return;
        }
      }

      _lastWasFiltered = true;
    } else {
      // If it doesn't match the log pattern at all, pass it through.
      if (!_lastWasFiltered)
        _linesController.add(line);
    }
  }

  void _stop() {
    // TODO(devoncarew): We should remove adb port forwarding here.

    _process?.kill();
  }
}

class _AndroidDevicePortForwarder extends DevicePortForwarder {
  _AndroidDevicePortForwarder(this.device);

  final AndroidDevice device;

  static int _extractPort(String portString) {
    return int.parse(portString.trim(), onError: (_) => null);
  }

  @override
  List<ForwardedPort> get forwardedPorts {
    final List<ForwardedPort> ports = <ForwardedPort>[];

    String stdout = runCheckedSync(device.adbCommandForDevice(
      <String>['forward', '--list']
    ));

    List<String> lines = LineSplitter.split(stdout).toList();
    for (String line in lines) {
      if (line.startsWith(device.id)) {
        List<String> splitLine = line.split("tcp:");

        // Sanity check splitLine.
        if (splitLine.length != 3)
          continue;

        // Attempt to extract ports.
        int hostPort = _extractPort(splitLine[1]);
        int devicePort = _extractPort(splitLine[2]);

        // Failed, skip.
        if ((hostPort == null) || (devicePort == null))
          continue;

        ports.add(new ForwardedPort(hostPort, devicePort));
      }
    }

    return ports;
  }

  @override
  Future<int> forward(int devicePort, { int hostPort }) async {
    if ((hostPort == null) || (hostPort == 0)) {
      // Auto select host port.
      hostPort = await findAvailablePort();
    }

    runCheckedSync(device.adbCommandForDevice(
      <String>['forward', 'tcp:$hostPort', 'tcp:$devicePort']
    ));

    return hostPort;
  }

  @override
  Future<Null> unforward(ForwardedPort forwardedPort) async {
    runCheckedSync(device.adbCommandForDevice(
      <String>['forward', '--remove', 'tcp:${forwardedPort.hostPort}']
    ));
  }
}