// Copyright 2017 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 'package:meta/meta.dart';

import '../application_package.dart';
import '../base/common.dart';
import '../base/io.dart';
import '../base/logger.dart';
import '../base/platform.dart';
import '../base/process.dart';
import '../base/process_manager.dart';
import '../base/time.dart';
import '../build_info.dart';
import '../device.dart';
import '../globals.dart';
import '../vmservice.dart';

import 'fuchsia_sdk.dart';
import 'fuchsia_workflow.dart';

final String _ipv4Loopback = InternetAddress.loopbackIPv4.address;
final String _ipv6Loopback = InternetAddress.loopbackIPv6.address;

// Enables testing the fuchsia isolate discovery
Future<VMService> _kDefaultFuchsiaIsolateDiscoveryConnector(Uri uri) {
  return VMService.connect(uri);
}

/// Read the log for a particular device.
class _FuchsiaLogReader extends DeviceLogReader {
  _FuchsiaLogReader(this._device, [this._app]);

  static final RegExp _flutterLogOutput = RegExp(r'INFO: \w+\(flutter\): ');

  FuchsiaDevice _device;
  ApplicationPackage _app;

  @override
  String get name => _device.name;

  Stream<String> _logLines;
  @override
  Stream<String> get logLines {
    _logLines ??= _processLogs(fuchsiaSdk.syslogs());
    return _logLines;
  }

  Stream<String> _processLogs(Stream<String> lines) {
    // Get the starting time of the log processor to filter logs from before
    // the process attached.
    final DateTime startTime = systemClock.now();
    // Determine if line comes from flutter, and optionally whether it matches
    // the correct fuchsia module.
    final RegExp matchRegExp = _app == null
      ? _flutterLogOutput
      : RegExp('INFO: ${_app.name}\\(flutter\\): ');
    return Stream<String>.eventTransformed(
      lines,
      (Sink<String> outout) => _FuchsiaLogSink(outout, matchRegExp, startTime),
    );
  }

  @override
  String toString() => name;
}

class _FuchsiaLogSink implements EventSink<String> {
  _FuchsiaLogSink(this._outputSink, this._matchRegExp, this._startTime);

  static final RegExp _utcDateOutput = RegExp(r'\d+\-\d+\-\d+ \d+:\d+:\d+');
  final EventSink<String> _outputSink;
  final RegExp _matchRegExp;
  final DateTime _startTime;

  @override
  void add(String line) {
    if (!_matchRegExp.hasMatch(line)) {
      return;
    }
    final String rawDate = _utcDateOutput.firstMatch(line)?.group(0);
    if (rawDate == null) {
      return;
    }
    final DateTime logTime = DateTime.parse(rawDate);
    if (logTime.millisecondsSinceEpoch < _startTime.millisecondsSinceEpoch) {
      return;
    }
    _outputSink.add('[${logTime.toLocal()}] Flutter: ${line.split(_matchRegExp).last}');
  }

  @override
  void addError(Object error, [ StackTrace stackTrace ]) {
    _outputSink.addError(error, stackTrace);
  }

  @override
  void close() { _outputSink.close(); }
}

class FuchsiaDevices extends PollingDeviceDiscovery {
  FuchsiaDevices() : super('Fuchsia devices');

  @override
  bool get supportsPlatform => platform.isLinux || platform.isMacOS;

  @override
  bool get canListAnything => fuchsiaWorkflow.canListDevices;

  @override
  Future<List<Device>> pollingGetDevices() async {
    if (!fuchsiaWorkflow.canListDevices) {
      return <Device>[];
    }
    final String text = await fuchsiaSdk.listDevices();
    if (text == null || text.isEmpty) {
      return <Device>[];
    }
    final List<FuchsiaDevice> devices = parseListDevices(text);
    return devices;
  }

  @override
  Future<List<String>> getDiagnostics() async => const <String>[];
}

@visibleForTesting
List<FuchsiaDevice> parseListDevices(String text) {
  final List<FuchsiaDevice> devices = <FuchsiaDevice>[];
  for (String rawLine in text.trim().split('\n')) {
    final String line = rawLine.trim();
    // ['ip', 'device name']
    final List<String> words = line.split(' ');
    if (words.length < 2) {
      continue;
    }
    final String name = words[1];
    final String id = words[0];
    devices.add(FuchsiaDevice(id, name: name));
  }
  return devices;
}

class FuchsiaDevice extends Device {
  FuchsiaDevice(String id, { this.name }) : super(id);

  @override
  bool get supportsHotReload => true;

  @override
  bool get supportsHotRestart => false;

  @override
  bool get supportsStopApp => false;

  @override
  final String name;

  @override
  Future<bool> get isLocalEmulator async => false;

  @override
  bool get supportsStartPaused => false;

  @override
  Future<bool> isAppInstalled(ApplicationPackage app) async => false;

  @override
  Future<bool> isLatestBuildInstalled(ApplicationPackage app) async => false;

  @override
  Future<bool> installApp(ApplicationPackage app) => Future<bool>.value(false);

  @override
  Future<bool> uninstallApp(ApplicationPackage app) async => false;

  @override
  bool isSupported() => true;

  @override
  Future<LaunchResult> startApp(
    ApplicationPackage package, {
    String mainPath,
    String route,
    DebuggingOptions debuggingOptions,
    Map<String, dynamic> platformArgs,
    bool prebuiltApplication = false,
    bool usesTerminalUi = true,
    bool ipv6 = false,
  }) => Future<void>.error('unimplemented');

  @override
  Future<bool> stopApp(ApplicationPackage app) async {
    // Currently we don't have a way to stop an app running on Fuchsia.
    return false;
  }

  @override
  Future<TargetPlatform> get targetPlatform async => TargetPlatform.fuchsia;

  @override
  Future<String> get sdkNameAndVersion async => 'Fuchsia';

  @override
  DeviceLogReader getLogReader({ ApplicationPackage app }) => _logReader ??= _FuchsiaLogReader(this, app);
  _FuchsiaLogReader _logReader;

  @override
  DevicePortForwarder get portForwarder => _portForwarder ??= _FuchsiaPortForwarder(this);
  _FuchsiaPortForwarder _portForwarder;

  @override
  void clearLogs() { }

  @override
  bool get supportsScreenshot => false;

  bool get ipv6 {
    // Workaround for https://github.com/dart-lang/sdk/issues/29456
    final String fragment = id.split('%').first;
    try {
      Uri.parseIPv6Address(fragment);
      return true;
    } on FormatException {
      return false;
    }
  }

  /// List the ports currently running a dart observatory.
  Future<List<int>> servicePorts() async {
    final String findOutput = await shell('find /hub -name vmservice-port');
    if (findOutput.trim() == '') {
      throwToolExit('No Dart Observatories found. Are you running a debug build?');
      return null;
    }
    final List<int> ports = <int>[];
    for (String path in findOutput.split('\n')) {
      if (path == '') {
        continue;
      }
      final String lsOutput = await shell('ls $path');
      for (String line in lsOutput.split('\n')) {
        if (line == '') {
          continue;
        }
        final int port = int.tryParse(line);
        if (port != null) {
          ports.add(port);
        }
      }
    }
    return ports;
  }

  /// Run `command` on the Fuchsia device shell.
  Future<String> shell(String command) async {
    final RunResult result = await runAsync(<String>[
      'ssh', '-F', fuchsiaArtifacts.sshConfig.absolute.path, id, command]);
    if (result.exitCode != 0) {
      throwToolExit('Command failed: $command\nstdout: ${result.stdout}\nstderr: ${result.stderr}');
      return null;
    }
    return result.stdout;
  }

  /// Finds the first port running a VM matching `isolateName` from the
  /// provided set of `ports`.
  ///
  /// Returns null if no isolate port can be found.
  ///
  // TODO(jonahwilliams): replacing this with the hub will require an update
  // to the flutter_runner.
  Future<int> findIsolatePort(String isolateName, List<int> ports) async {
    for (int port in ports) {
      try {
        // Note: The square-bracket enclosure for using the IPv6 loopback
        // didn't appear to work, but when assigning to the IPv4 loopback device,
        // netstat shows that the local port is actually being used on the IPv6
        // loopback (::1).
        final Uri uri = Uri.parse('http://[$_ipv6Loopback]:$port');
        final VMService vmService = await VMService.connect(uri);
        await vmService.getVM();
        await vmService.refreshViews();
        for (FlutterView flutterView in vmService.vm.views) {
          if (flutterView.uiIsolate == null) {
            continue;
          }
          final Uri address = flutterView.owner.vmService.httpAddress;
          if (flutterView.uiIsolate.name.contains(isolateName)) {
            return address.port;
          }
        }
      } on SocketException catch (err) {
        printTrace('Failed to connect to $port: $err');
      }
    }
    throwToolExit('No ports found running $isolateName');
    return null;
  }

  FuchsiaIsolateDiscoveryProtocol  getIsolateDiscoveryProtocol(String isolateName) => FuchsiaIsolateDiscoveryProtocol(this, isolateName);
}

class FuchsiaIsolateDiscoveryProtocol {
  FuchsiaIsolateDiscoveryProtocol(
    this._device,
    this._isolateName, [
    this._vmServiceConnector = _kDefaultFuchsiaIsolateDiscoveryConnector,
    this._pollOnce = false,
  ]);

  static const Duration _pollDuration = Duration(seconds: 10);
  final Map<int, VMService> _ports = <int, VMService>{};
  final FuchsiaDevice _device;
  final String _isolateName;
  final Completer<Uri> _foundUri = Completer<Uri>();
  final Future<VMService> Function(Uri) _vmServiceConnector;
  // whether to only poll once.
  final bool _pollOnce;
  Timer _pollingTimer;
  Status _status;

  FutureOr<Uri> get uri {
    if (_uri != null) {
      return _uri;
    }
    _status ??= logger.startProgress(
      'Waiting for a connection from $_isolateName on ${_device.name}...',
      timeout: null, // could take an arbitrary amount of time
    );
    _pollingTimer ??= Timer(_pollDuration, _findIsolate);
    return _foundUri.future.then((Uri uri) {
      _uri = uri;
      return uri;
    });
  }
  Uri _uri;

  void dispose() {
    if (!_foundUri.isCompleted) {
      _status?.cancel();
      _status = null;
      _pollingTimer?.cancel();
      _pollingTimer = null;
      _foundUri.completeError(Exception('Did not complete'));
    }
  }

  Future<void> _findIsolate() async {
    final List<int> ports = await _device.servicePorts();
    for (int port in ports) {
      VMService service;
      if (_ports.containsKey(port)) {
        service = _ports[port];
      } else {
        final int localPort = await _device.portForwarder.forward(port);
        try {
          final Uri uri = Uri.parse('http://[$_ipv6Loopback]:$localPort');
          service = await _vmServiceConnector(uri);
          _ports[port] = service;
        } on SocketException catch (err) {
          printTrace('Failed to connect to $localPort: $err');
          continue;
        }
      }
      await service.getVM();
      await service.refreshViews();
      for (FlutterView flutterView in service.vm.views) {
        if (flutterView.uiIsolate == null) {
          continue;
        }
        final Uri address = flutterView.owner.vmService.httpAddress;
        if (flutterView.uiIsolate.name.contains(_isolateName)) {
          _foundUri.complete(_device.ipv6
            ? Uri.parse('http://[$_ipv6Loopback]:${address.port}/')
            : Uri.parse('http://$_ipv4Loopback:${address.port}/'));
          _status.stop();
          return;
        }
      }
    }
    if (_pollOnce) {
      _foundUri.completeError(Exception('Max iterations exceeded'));
      _status.stop();
      return;
    }
    _pollingTimer = Timer(_pollDuration, _findIsolate);
  }
}

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

  final FuchsiaDevice device;
  final Map<int, Process> _processes = <int, Process>{};

  @override
  Future<int> forward(int devicePort, { int hostPort }) async {
    hostPort ??= await _findPort();
    // Note: the provided command works around a bug in -N, see US-515
    // for more explanation.
    final List<String> command = <String>[
      'ssh', '-6', '-F', fuchsiaArtifacts.sshConfig.absolute.path, '-nNT', '-vvv', '-f',
      '-L', '$hostPort:$_ipv4Loopback:$devicePort', device.id, 'true',
    ];
    final Process process = await processManager.start(command);
    unawaited(process.exitCode.then((int exitCode) {
      if (exitCode != 0) {
        throwToolExit('Failed to forward port:$devicePort');
      }
    }));
    _processes[hostPort] = process;
    _forwardedPorts.add(ForwardedPort(hostPort, devicePort));
    return hostPort;
  }

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

  @override
  Future<void> unforward(ForwardedPort forwardedPort) async {
    _forwardedPorts.remove(forwardedPort);
    final Process process = _processes.remove(forwardedPort.hostPort);
    process?.kill();
    final List<String> command = <String>[
        'ssh', '-F', fuchsiaArtifacts.sshConfig.absolute.path, '-O', 'cancel', '-vvv',
        '-L', '${forwardedPort.hostPort}:$_ipv4Loopback:${forwardedPort.devicePort}', device.id];
    final ProcessResult result = await processManager.run(command);
    if (result.exitCode != 0) {
      throwToolExit(result.stderr);
    }
  }

  static Future<int> _findPort() async {
    int port = 0;
    ServerSocket serverSocket;
    try {
      serverSocket = await ServerSocket.bind(_ipv4Loopback, 0);
      port = serverSocket.port;
    } catch (e) {
      // Failures are signaled by a return value of 0 from this function.
      printTrace('_findPort failed: $e');
    }
    if (serverSocket != null)
      await serverSocket.close();
    return port;
  }
}

class FuchsiaModulePackage extends ApplicationPackage {
  FuchsiaModulePackage({@required this.name}) : super(id: name);

  @override
  final String name;
}