// Copyright (c) 2015, 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 dart._vmservice;

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

part 'asset.dart';
part 'client.dart';
part 'devfs.dart';
part 'constants.dart';
part 'running_isolate.dart';
part 'running_isolates.dart';
part 'message.dart';
part 'message_router.dart';
part 'named_lookup.dart';

final isolateControlPort = RawReceivePort();
final scriptLoadPort = RawReceivePort();

abstract class IsolateEmbedderData {
  void cleanup();
}

String _makeAuthToken() {
  final kTokenByteSize = 8;
  Uint8List bytes = Uint8List(kTokenByteSize);
  Random random = Random.secure();
  for (int i = 0; i < kTokenByteSize; i++) {
    bytes[i] = random.nextInt(256);
  }
  return base64Url.encode(bytes);
}

// The randomly generated auth token used to access the VM service.
final serviceAuthToken = _makeAuthToken();

// This is for use by the embedder. It is a map from the isolateId to
// anything implementing IsolateEmbedderData. When an isolate goes away,
// the cleanup method will be invoked after being removed from the map.
final isolateEmbedderData = <int, IsolateEmbedderData>{};

// These must be kept in sync with the declarations in vm/json_stream.h and
// pkg/dds/lib/src/rpc_error_codes.dart.
const kParseError = -32700;
const kInvalidRequest = -32600;
const kMethodNotFound = -32601;
const kInvalidParams = -32602;
const kInternalError = -32603;

const kExtensionError = -32000;

const kFeatureDisabled = 100;
const kCannotAddBreakpoint = 102;
const kStreamAlreadySubscribed = 103;
const kStreamNotSubscribed = 104;
const kIsolateMustBeRunnable = 105;
const kIsolateMustBePaused = 106;
const kCannotResume = 107;
const kIsolateIsReloading = 108;
const kIsolateReloadBarred = 109;
const kIsolateMustHaveReloaded = 110;
const kServiceAlreadyRegistered = 111;
const kServiceDisappeared = 112;
const kExpressionCompilationError = 113;
const kInvalidTimelineRequest = 114;

// Experimental (used in private rpcs).
const kFileSystemAlreadyExists = 1001;
const kFileSystemDoesNotExist = 1002;
const kFileDoesNotExist = 1003;

final _errorMessages = <int, String>{
  kInvalidParams: 'Invalid params',
  kInternalError: 'Internal error',
  kFeatureDisabled: 'Feature is disabled',
  kStreamAlreadySubscribed: 'Stream already subscribed',
  kStreamNotSubscribed: 'Stream not subscribed',
  kFileSystemAlreadyExists: 'File system already exists',
  kFileSystemDoesNotExist: 'File system does not exist',
  kFileDoesNotExist: 'File does not exist',
  kServiceAlreadyRegistered: 'Service already registered',
  kServiceDisappeared: 'Service has disappeared',
  kExpressionCompilationError: 'Expression compilation error',
  kInvalidTimelineRequest: 'The timeline related request could not be completed'
      'due to the current configuration',
};

String encodeRpcError(Message message, int code, {String? details}) {
  final response = <String, dynamic>{
    'jsonrpc': '2.0',
    'id': message.serial,
    'error': {
      'code': code,
      'message': _errorMessages[code],
    },
  };
  if (details != null) {
    response['error']['data'] = <String, String>{
      'details': details,
    };
  }
  return json.encode(response);
}

String encodeMissingParamError(Message message, String param) =>
    encodeRpcError(message, kInvalidParams,
        details: "${message.method} expects the '${param}' parameter");

String encodeInvalidParamError(Message message, String param) {
  final value = message.params[param];
  return encodeRpcError(message, kInvalidParams,
      details: "${message.method}: invalid '${param}' parameter: ${value}");
}

String encodeCompilationError(Message message, String diagnostic) =>
    encodeRpcError(message, kExpressionCompilationError, details: diagnostic);

String encodeResult(Message message, Map result) => json.encode({
      'jsonrpc': '2.0',
      'id': message.serial,
      'result': result,
    });

String encodeSuccess(Message message) =>
    encodeResult(message, {'type': 'Success'});

const shortDelay = Duration(milliseconds: 10);

/// Called when the server should be started.
typedef Future ServerStartCallback();

/// Called when the server should be stopped.
typedef Future ServerStopCallback();

/// Called when DDS has connected.
typedef Future<void> DdsConnectedCallback();

/// Called when DDS has disconnected.
typedef Future<void> DdsDisconnectedCallback();

/// Called when the service is exiting.
typedef Future CleanupCallback();

/// Called to create a temporary directory
typedef Future<Uri> CreateTempDirCallback(String base);

/// Called to delete a directory
typedef Future DeleteDirCallback(Uri path);

/// Called to write a file.
typedef Future WriteFileCallback(Uri path, List<int> bytes);

/// Called to write a stream into a file.
typedef Future WriteStreamFileCallback(Uri path, Stream<List<int>> bytes);

/// Called to read a file.
typedef Future<List<int>> ReadFileCallback(Uri path);

/// Called to list all files under some path.
typedef Future<List<Map<String, dynamic>>> ListFilesCallback(Uri path);

/// Called when we need information about the server.
typedef Future<Uri> ServerInformamessage_routertionCallback();

/// Called when we need information about the server.
typedef Uri? ServerInformationCallback();

/// Called when we want to [enable] or disable the web server or silence VM
/// service console messages.
typedef Future<Uri?> WebServerControlCallback(bool enable, bool? silenceOutput);

/// Called when we want to [enable] or disable new websocket connections to the
/// server.
typedef void WebServerAcceptNewWebSocketConnectionsCallback(bool enable);

/// Hooks that are setup by the embedder.
class VMServiceEmbedderHooks {
  static ServerStartCallback? serverStart;
  static ServerStopCallback? serverStop;
  static DdsConnectedCallback? ddsConnected;
  static DdsDisconnectedCallback? ddsDisconnected;
  static CleanupCallback? cleanup;
  static CreateTempDirCallback? createTempDir;
  static DeleteDirCallback? deleteDir;
  static WriteFileCallback? writeFile;
  static WriteStreamFileCallback? writeStreamFile;
  static ReadFileCallback? readFile;
  static ListFilesCallback? listFiles;
  static ServerInformationCallback? serverInformation;
  static WebServerControlCallback? webServerControl;
  static WebServerAcceptNewWebSocketConnectionsCallback?
      acceptNewWebSocketConnections;
}

class _ClientResumePermissions {
  final List<Client> clients = [];
  int permissionsMask = 0;
}

class VMService extends MessageRouter {
  static VMService? _instance;

  static const serviceNamespace = 's';

  /// Collection of currently connected clients.
  final clients = NamedLookup<Client>(prologue: serviceNamespace);
  final _serviceRequests = IdGenerator(prologue: 'sr');

  /// Mapping of client names to all clients of that name and their resume
  /// permissions.
  final Map<String, _ClientResumePermissions> clientResumePermissions = {};

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

  /// Flag to indicate VM service is exiting.
  bool isExiting = false;

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

  final devfs = DevFS();

  Uri? get ddsUri => _ddsUri;
  Uri? _ddsUri;

  Future<String> _yieldControlToDDS(Message message) async {
    final acceptNewWebSocketConnections =
        VMServiceEmbedderHooks.acceptNewWebSocketConnections;
    if (acceptNewWebSocketConnections == null) {
      return encodeRpcError(message, kFeatureDisabled,
          details:
              'Embedder does not support yielding to a VM service intermediary.');
    }

    if (_ddsUri != null) {
      return encodeRpcError(message, kFeatureDisabled,
          details: 'A DDS instance is already connected at ${_ddsUri!}.');
    }

    final uri = message.params['uri'];
    if (uri == null) {
      return encodeMissingParamError(message, 'uri');
    }
    // DDS can only take control if there is no other clients connected
    // directly to the VM service.
    if (clients.length > 1) {
      return encodeRpcError(message, kFeatureDisabled,
          details:
              'Existing VM service clients prevent DDS from taking control.');
    }
    acceptNewWebSocketConnections(false);
    _ddsUri = Uri.parse(uri);
    await VMServiceEmbedderHooks.ddsConnected!();
    return encodeSuccess(message);
  }

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

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

    for (final service in client.services.keys) {
      _eventMessageHandler(
          'Service',
          Response.json({
            'jsonrpc': '2.0',
            'method': 'streamNotify',
            'params': {
              'streamId': 'Service',
              'event': {
                'type': 'Event',
                'kind': 'ServiceUnregistered',
                'timestamp': DateTime.now().millisecondsSinceEpoch,
                'service': service,
                'method': namespace + '.' + service,
              }
            }
          }));
    }
    // Complete all requests as failed
    for (final handle in client.serviceHandles.values) {
      handle(null);
    }
    if (clients.isEmpty) {
      // If DDS was connected, we are in single client mode and need to
      // allow for new websocket connections.
      final acceptNewWebSocketConnections =
          VMServiceEmbedderHooks.acceptNewWebSocketConnections;
      if (_ddsUri != null && acceptNewWebSocketConnections != null) {
        _ddsUri = null;
        VMServiceEmbedderHooks.ddsDisconnected!();
        acceptNewWebSocketConnections(true);
      }
    }
  }

  void _eventMessageHandler(String streamId, Response event) {
    for (final 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);
        isolateEmbedderData.remove(portId)?.cleanup();
        break;
    }
  }

  Future<void> _serverMessageHandler(
      int code, SendPort sp, bool enable, bool? silenceOutput) async {
    switch (code) {
      case Constants.WEB_SERVER_CONTROL_MESSAGE_ID:
        final webServerControl = VMServiceEmbedderHooks.webServerControl;
        if (webServerControl == null) {
          sp.send(null);
          return;
        }
        final uri = await webServerControl(enable, silenceOutput);
        sp.send(uri);
        break;
      case Constants.SERVER_INFO_MESSAGE_ID:
        final serverInformation = VMServiceEmbedderHooks.serverInformation;
        if (serverInformation == null) {
          sp.send(null);
          return;
        }
        final uri = await serverInformation();
        sp.send(uri);
        break;
    }
  }

  Future<void> _handleNativeRpcCall(message, SendPort replyPort) async {
    // Keep in sync with 'runtime/vm/service_isolate.cc:InvokeServiceRpc'.
    Response response;

    try {
      final rpc = Message.fromJsonRpc(
          null, json.decode(utf8.decode(message as List<int>)));
      if (rpc.type != MessageType.Request) {
        response = Response.internalError(
            'The client sent a non-request json-rpc message.');
      } else {
        response = (await routeRequest(this, rpc))!;
      }
    } catch (exception) {
      response = Response.internalError(
          'The rpc call resulted in exception: $exception.');
    }
    late List<int> bytes;
    switch (response.kind) {
      case ResponsePayloadKind.String:
        bytes = utf8.encode(response.payload);
        bytes = bytes is Uint8List ? bytes : Uint8List.fromList(bytes);
        break;
      case ResponsePayloadKind.Binary:
      case ResponsePayloadKind.Utf8String:
        bytes = response.payload as Uint8List;
        break;
    }
    replyPort.send(bytes);
  }

  Future _exit() async {
    isExiting = true;

    final serverStop = VMServiceEmbedderHooks.serverStop;
    // Stop the server.
    if (serverStop != null) {
      await serverStop();
    }

    // Close receive ports.
    isolateControlPort.close();
    scriptLoadPort.close();

    // Create a copy of the set as a list because client.disconnect() will
    // alter the connected clients set.
    final clientsList = clients.toList();
    for (final client in clientsList) {
      client.disconnect();
    }
    devfs.cleanup();
    final cleanup = VMServiceEmbedderHooks.cleanup;
    if (cleanup != null) {
      await cleanup();
    }

    // Notify the VM that we have exited.
    _onExit();
  }

  void messageHandler(message) {
    if (message is List) {
      if (message.length == 2) {
        // This is an event.
        _eventMessageHandler(message[0], Response.from(message[1]));
        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;
      }
      final opcode = message[0];
      if (message.length == 3 && opcode == Constants.METHOD_CALL_FROM_NATIVE) {
        _handleNativeRpcCall(message[1], message[2]);
        return;
      }
      if (message.length == 4) {
        if ((opcode == Constants.WEB_SERVER_CONTROL_MESSAGE_ID) ||
            (opcode == Constants.SERVER_INFO_MESSAGE_ID)) {
          // This is a message interacting with the web server.
          _serverMessageHandler(message[0], message[1], message[2], message[3]);
          return;
        } else {
          // This is a message informing us of the birth or death of an
          // isolate.
          _controlMessageHandler(
              message[0], message[1], message[2], message[3]);
          return;
        }
      }
      print('Internal vm-service error: ignoring illegal message: $message');
    }
  }

  VMService._internal() : eventPort = isolateControlPort {
    eventPort.handler = messageHandler;
  }

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

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

  Client? _findFirstClientThatHandlesService(String service) {
    for (Client c in clients) {
      if (c.services.containsKey(service)) {
        return c;
      }
    }
    return null;
  }

  static const kServiceStream = 'Service';
  static const serviceStreams = <String>[kServiceStream];

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

    if (client.streams.contains(streamId)) {
      return encodeRpcError(message, kStreamAlreadySubscribed);
    }
    if (!_isAnyClientSubscribed(streamId)) {
      if (!serviceStreams.contains(streamId) && !_vmListenStream(streamId)) {
        return encodeRpcError(message, kInvalidParams,
            details: "streamListen: invalid 'streamId' parameter: ${streamId}");
      }
    }

    // Some streams can generate events or side effects after registration
    switch (streamId) {
      case kServiceStream:
        for (Client c in clients) {
          if (c == client) continue;
          for (String service in c.services.keys) {
            _sendServiceRegisteredEvent(c, service, target: client);
          }
        }
        ;
        break;
    }

    client.streams.add(streamId);
    return encodeSuccess(message);
  }

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

    if (!client.streams.contains(streamId)) {
      return encodeRpcError(message, kStreamNotSubscribed);
    }
    client.streams.remove(streamId);
    if (!serviceStreams.contains(streamId) &&
        !_isAnyClientSubscribed(streamId)) {
      _vmCancelStream(streamId);
    }

    return encodeSuccess(message);
  }

  static bool _hasNamespace(String method) =>
      method.contains('.') &&
      _getNamespace(method).startsWith(serviceNamespace);
  static String _getNamespace(String method) => method.split('.').first;
  static String _getMethod(String method) => method.split('.').last;

  Future<String> _registerService(Message message) async {
    final client = message.client!;
    final service = message.params['service'];
    final alias = message.params['alias'];

    if (service is! String || service == '') {
      return encodeRpcError(message, kInvalidParams,
          details: "registerService: invalid 'service' parameter: ${service}");
    }
    if (alias is! String || alias == '') {
      return encodeRpcError(message, kInvalidParams,
          details: "registerService: invalid 'alias' parameter: ${alias}");
    }
    if (client.services.containsKey(service)) {
      return encodeRpcError(message, kServiceAlreadyRegistered);
    }
    client.services[service] = alias;

    bool removed = false;
    try {
      // Do not send streaming events to the client which registers the service
      removed = client.streams.remove(kServiceStream);
      await _sendServiceRegisteredEvent(client, service);
    } finally {
      if (removed) client.streams.add(kServiceStream);
    }

    return encodeSuccess(message);
  }

  Future<void> _sendServiceRegisteredEvent(Client client, String service,
      {Client? target}) async {
    final namespace = clients.keyOf(client);
    final alias = client.services[service];
    final event = Response.json({
      'jsonrpc': '2.0',
      'method': 'streamNotify',
      'params': {
        'streamId': kServiceStream,
        'event': {
          'type': 'Event',
          'kind': 'ServiceRegistered',
          'timestamp': DateTime.now().millisecondsSinceEpoch,
          'service': service,
          'method': namespace + '.' + service,
          'alias': alias
        }
      }
    });
    if (target == null) {
      _eventMessageHandler(kServiceStream, event);
    } else {
      target.post(event);
    }
  }

  Future<String> _handleService(Message message) async {
    final namespace = _getNamespace(message.method!);
    final method = _getMethod(message.method!);
    final client = clients[namespace];
    if (client.services.containsKey(method)) {
      final id = _serviceRequests.newId();
      final oldId = message.serial;
      final completer = Completer<String>();
      client.serviceHandles[id] = (Message? m) {
        if (m != null) {
          completer.complete(json.encode(m.forwardToJson({'id': oldId})));
        } else {
          completer.complete(encodeRpcError(message, kServiceDisappeared));
        }
      };
      client.post(
          Response.json(message.forwardToJson({'id': id, 'method': method})));
      return completer.future;
    }
    return encodeRpcError(message, kMethodNotFound,
        details: 'Unknown service: ${message.method}');
  }

  Future<String> _getSupportedProtocols(Message message) async {
    final version = json.decode(
      utf8.decode(
        (await Message.forMethod('getVersion').sendToVM()).payload,
      ),
    )['result'];
    final protocols = {
      'type': 'ProtocolList',
      'protocols': [
        {
          'protocolName': 'VM Service',
          'major': version['major'],
          'minor': version['minor'],
        },
      ],
    };
    return encodeResult(message, protocols);
  }

  Future<Response?> routeRequest(VMService _, Message message) async {
    final response = await _routeRequestImpl(message);
    if (response == null) {
      // We should only have a null response for Notifications.
      assert(message.type == MessageType.Notification);
      return null;
    }
    return Response.from(response);
  }

  Future _routeRequestImpl(Message message) async {
    try {
      if (message.completed) {
        return await message.response;
      }
      if (message.method == '_yieldControlToDDS') {
        return await _yieldControlToDDS(message);
      }
      if (message.method == 'streamListen') {
        return await _streamListen(message);
      }
      if (message.method == 'streamCancel') {
        return await _streamCancel(message);
      }
      if (message.method == 'registerService') {
        return await _registerService(message);
      }
      if (message.method == 'getSupportedProtocols') {
        return await _getSupportedProtocols(message);
      }
      if (devfs.shouldHandleMessage(message)) {
        return await devfs.handleMessage(message);
      }
      if (_hasNamespace(message.method!)) {
        return await _handleService(message);
      }
      if (message.params['isolateId'] != null) {
        return await runningIsolates.routeRequest(this, message);
      }
      return await message.sendToVM();
    } catch (e, st) {
      message.setErrorResponse(kInternalError, 'Unexpected exception:$e\n$st');
      return message.response;
    }
  }

  void routeResponse(message) {
    final client = message.client!;
    if (client.serviceHandles.containsKey(message.serial)) {
      client.serviceHandles.remove(message.serial)!(message);
      _serviceRequests.release(message.serial);
    }
  }
}

@pragma('vm:entry-point',
    const bool.fromEnvironment('dart.vm.product') ? false : 'call')
RawReceivePort boot() {
  // Return the port we expect isolate control messages on.
  return isolateControlPort;
}

@pragma('vm:entry-point', !const bool.fromEnvironment('dart.vm.product'))
// ignore: unused_element
void _registerIsolate(int port_id, SendPort sp, String name) =>
    VMService().runningIsolates.isolateStartup(port_id, sp, name);

/// Notify the VM that the service is running.
void _onStart() native 'VMService_OnStart';

/// Notify the VM that the service is no longer running.
void _onExit() native 'VMService_OnExit';

/// Notify the VM that the server's address has changed.
void onServerAddressChange(String? address) {
  _onServerAddressChange(address);
}

void _onServerAddressChange(String? address)
    native 'VMService_OnServerAddressChange';

/// Subscribe to a service stream.
bool _vmListenStream(String streamId) native 'VMService_ListenStream';

/// Cancel a subscription to a service stream.
void _vmCancelStream(String streamId) native 'VMService_CancelStream';

/// Get the bytes to the tar archive.
Uint8List _requestAssets() native 'VMService_RequestAssets';