// Copyright (c) 2013, 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.

library vmservice;

import 'dart:async';
import 'dart:convert';
import 'dart:isolate';
import 'dart:typed_data';

part 'client.dart';
part 'constants.dart';
part 'running_isolate.dart';
part 'running_isolates.dart';
part 'message.dart';
part 'message_router.dart';

final RawReceivePort isolateLifecyclePort = new RawReceivePort();
final RawReceivePort scriptLoadPort = new RawReceivePort();

typedef ShutdownCallback();

class VMService extends MessageRouter {
  static VMService _instance;

  /// Collection of currently connected clients.
  final Set<Client> clients = new Set<Client>();

  /// Collection of currently running isolates.
  RunningIsolates runningIsolates = new RunningIsolates();

  /// A port used to receive events from the VM.
  final RawReceivePort eventPort;

  ShutdownCallback onShutdown;

  void _addClient(Client client) {
    assert(client.streams.isEmpty);
    clients.add(client);
  }

  void _removeClient(Client client) {
    clients.remove(client);
    for (var streamId in client.streams) {
      if (!_isAnyClientSubscribed(streamId)) {
        _vmCancelStream(streamId);
      }
    }
  }

  void _eventMessageHandler(List eventMessage) {
    var streamId = eventMessage[0];
    var event = eventMessage[1];
    for (var client in clients) {
      if (client.sendEvents && client.streams.contains(streamId)) {
        client.post(event);
      }
    }
  }

  void _controlMessageHandler(int code,
                              int portId,
                              SendPort sp,
                              String name) {
    switch (code) {
      case Constants.ISOLATE_STARTUP_MESSAGE_ID:
        runningIsolates.isolateStartup(portId, sp, name);
      break;
      case Constants.ISOLATE_SHUTDOWN_MESSAGE_ID:
        runningIsolates.isolateShutdown(portId, sp);
      break;
    }
  }

  void _exit() {
    isolateLifecyclePort.close();
    scriptLoadPort.close();
    // Create a copy of the set as a list because client.close() alters the set.
    var clientsList = clients.toList();
    for (var client in clientsList) {
      client.close();
    }
    // Call embedder shutdown hook after the internal shutdown.
    if (onShutdown != null) {
      onShutdown();
    }
    _onExit();
  }

  void messageHandler(message) {
    if (message is List) {
      if (message.length == 2) {
        // This is an event.
        assert(message[0] is String);
        assert(message[1] is String || message[1] is Uint8List);
        _eventMessageHandler(message);
        return;
      }
      if (message.length == 1) {
        // This is a control message directing the vm service to exit.
        assert(message[0] == Constants.SERVICE_EXIT_MESSAGE_ID);
        _exit();
        return;
      }
      if (message.length == 4) {
        // This is a message informing us of the birth or death of an
        // isolate.
        _controlMessageHandler(message[0], message[1], message[2], message[3]);
        return;
      }
    }
    Logger.root.severe(
        'Internal vm-service error: ignoring illegal message: $message');
  }

  void _notSupported(_) {
    throw new UnimplementedError('Service script loading not supported.');
  }

  VMService._internal()
      : eventPort = isolateLifecyclePort {
    scriptLoadPort.handler = _notSupported;
    eventPort.handler = messageHandler;
  }

  factory VMService() {
    if (VMService._instance == null) {
      VMService._instance = new VMService._internal();
      _onStart();
    }
    return _instance;
  }

  void _clientCollection(Message message) {
    var members = [];
    var result = {};
    clients.forEach((client) {
      members.add(client.toJson());
    });
    result['type'] = 'ClientList';
    result['members'] = members;
    message.setResponse(JSON.encode(result));
  }

  // These must be kept in sync with the declarations in vm/json_stream.h.
  static const _kInvalidParams = -32602;
  static const _kStreamAlreadySubscribed = 103;
  static const _kStreamNotSubscribed = 104;

  var _errorMessages = {
    _kInvalidParams: 'Invalid params"',
    _kStreamAlreadySubscribed: 'Stream already subscribed',
    _kStreamNotSubscribed: 'Stream not subscribed',
  };

  String _encodeError(Message message, int code, {String details}) {
    var response = {
      'jsonrpc': '2.0',
      'id' : message.serial,
      'error' : {
        'code': code,
        'message': _errorMessages[code],
      },
    };
    if (details != null) {
      response['error']['data'] = {
        'details': details,
      };
    }
    return JSON.encode(response);
  }

  String _encodeResult(Message message, Map result) {
    var response = {
      'jsonrpc': '2.0',
      'id' : message.serial,
      'result' : result,
    };
    return JSON.encode(response);
  }

  bool _isAnyClientSubscribed(String streamId) {
    for (var client in clients) {
      if (client.streams.contains(streamId)) {
        return true;
      }
    }
    return false;
  }

  Future<String> _streamListen(Message message) async {
    var client = message.client;
    var streamId = message.params['streamId'];

    if (client.streams.contains(streamId)) {
      return _encodeError(message, _kStreamAlreadySubscribed);
    }
    if (!_isAnyClientSubscribed(streamId)) {
      if (!_vmListenStream(streamId)) {
        return _encodeError(
            message, _kInvalidParams,
            details:"streamListen: invalid 'streamId' parameter: ${streamId}");
      }
    }
    client.streams.add(streamId);

    var result = { 'type' : 'Success' };
    return _encodeResult(message, result);
  }

  Future<String> _streamCancel(Message message) async {
    var client = message.client;
    var streamId = message.params['streamId'];

    if (!client.streams.contains(streamId)) {
      return _encodeError(message, _kStreamNotSubscribed);
    }
    client.streams.remove(streamId);
    if (!_isAnyClientSubscribed(streamId)) {
      _vmCancelStream(streamId);
    }

    var result = { 'type' : 'Success' };
    return _encodeResult(message, result);
  }

  // TODO(johnmccutchan): Turn this into a command line tool that uses the
  // service library.
  Future<String> _getCrashDump(Message message) async {
    var client = message.client;
    final perIsolateRequests = [
        // ?isolateId=<isolate id> will be appended to each of these requests.
        // Isolate information.
        Uri.parse('getIsolate'),
        // State of heap.
        Uri.parse('_getAllocationProfile'),
        // Call stack + local variables.
        Uri.parse('getStack?_full=true'),
    ];

    // Snapshot of running isolates.
    var isolates = runningIsolates.isolates.values.toList();

    // Collect the mapping from request uris to responses.
    var responses = {
    };

    // Request VM.
    var getVM = Uri.parse('getVM');
    var getVmResponse = JSON.decode(
        await new Message.fromUri(client, getVM).sendToVM());
    responses[getVM.toString()] = getVmResponse['result'];

    // Request command line flags.
    var getFlagList = Uri.parse('getFlagList');
    var getFlagListResponse = JSON.decode(
        await new Message.fromUri(client, getFlagList).sendToVM());
    responses[getFlagList.toString()] = getFlagListResponse['result'];

    // Make requests to each isolate.
    for (var isolate in isolates) {
      for (var request in perIsolateRequests) {
        var message = new Message.forIsolate(client, request, isolate);
        // Decode the JSON and and insert it into the map. The map key
        // is the request Uri.
        var response = JSON.decode(await isolate.route(message));
        responses[message.toUri().toString()] = response['result'];
      }
      // Dump the object id ring requests.
      var message =
          new Message.forIsolate(client, Uri.parse('_dumpIdZone'), isolate);
      var response = JSON.decode(await isolate.route(message));
      // Insert getObject requests into responses map.
      for (var object in response['result']['objects']) {
        final requestUri =
            'getObject&isolateId=${isolate.serviceId}?objectId=${object["id"]}';
        responses[requestUri] = object;
      }
    }

    // Encode the entire crash dump.
    return _encodeResult(message, responses);
  }

  Future<String> route(Message message) {
    if (message.completed) {
      return message.response;
    }
    // TODO(turnidge): Update to json rpc.  BEFORE SUBMIT.
    if ((message.path.length == 1) && (message.path[0] == 'clients')) {
      _clientCollection(message);
      return message.response;
    }
    if (message.method == '_getCrashDump') {
      return _getCrashDump(message);
    }
    if (message.method == 'streamListen') {
      return _streamListen(message);
    }
    if (message.method == 'streamCancel') {
      return _streamCancel(message);
    }
    if (message.params['isolateId'] != null) {
      return runningIsolates.route(message);
    }
    return message.sendToVM();
  }
}

RawReceivePort boot() {
  // Return the port we expect isolate startup and shutdown messages on.
  return isolateLifecyclePort;
}

void _registerIsolate(int port_id, SendPort sp, String name) {
  var service = new VMService();
  service.runningIsolates.isolateStartup(port_id, sp, name);
}

void _onStart() native "VMService_OnStart";

void _onExit() native "VMService_OnExit";

bool _vmListenStream(String streamId) native "VMService_ListenStream";

void _vmCancelStream(String streamId) native "VMService_CancelStream";