puppeteer/src/Connection.ts

/**
 * Copyright 2017 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import {assert} from './helper';

import EventsModule = require('./Events');
const {Events} = EventsModule;

import debug = require('debug');
const debugProtocol = debug('puppeteer:protocol');

import EventEmitter = require('events');

interface ConnectionCallback {
    resolve: Function;
    reject: Function;
    error: Error;
    method: string;

}

export class Connection extends EventEmitter {
  _url: string;
  _transport: Puppeteer.ConnectionTransport;
  _delay: number;
  _lastId = 0;
  _sessions: Map<string, CDPSession> = new Map();
  _closed = false;

  _callbacks: Map<number, ConnectionCallback> = new Map();

  /**
   * @param {string} url
   * @param {!Puppeteer.ConnectionTransport} transport
   * @param {number=} delay
   */
  constructor(url: string, transport: Puppeteer.ConnectionTransport, delay = 0) {
    super();
    this._url = url;
    this._delay = delay;

    this._transport = transport;
    this._transport.onmessage = this._onMessage.bind(this);
    this._transport.onclose = this._onClose.bind(this);
  }

  static fromSession(session: CDPSession): Connection {
    return session._connection;
  }

  /**
   * @param {string} sessionId
   * @return {?CDPSession}
   */
  session(sessionId: string): CDPSession | null {
    return this._sessions.get(sessionId) || null;
  }

  url(): string {
    return this._url;
  }

  send<ReturnType extends {}>(method: string, params = {}): Promise<ReturnType> {
    const id = this._rawSend({method, params});
    return new Promise((resolve, reject) => {
      this._callbacks.set(id, {resolve, reject, error: new Error(), method});
    });
  }

  _rawSend(message: {}): number {
    const id = ++this._lastId;
    message = JSON.stringify(Object.assign({}, message, {id}));
    debugProtocol('SEND ► ' + message);
    this._transport.send(message);
    return id;
  }

  async _onMessage(message: string): Promise<void> {
    if (this._delay)
      await new Promise(f => setTimeout(f, this._delay));
    debugProtocol('◀ RECV ' + message);
    const object = JSON.parse(message);
    if (object.method === 'Target.attachedToTarget') {
      const sessionId = object.params.sessionId;
      const session = new CDPSession(this, object.params.targetInfo.type, sessionId);
      this._sessions.set(sessionId, session);
    } else if (object.method === 'Target.detachedFromTarget') {
      const session = this._sessions.get(object.params.sessionId);
      if (session) {
        session._onClosed();
        this._sessions.delete(object.params.sessionId);
      }
    }
    if (object.sessionId) {
      const session = this._sessions.get(object.sessionId);
      if (session)
        session._onMessage(object);
    } else if (object.id) {
      const callback = this._callbacks.get(object.id);
      // Callbacks could be all rejected if someone has called `.dispose()`.
      if (callback) {
        this._callbacks.delete(object.id);
        if (object.error)
          callback.reject(createProtocolError(callback.error, callback.method, object));
        else
          callback.resolve(object.result);
      }
    } else {
      this.emit(object.method, object.params);
    }
  }

  _onClose(): void {
    if (this._closed)
      return;
    this._closed = true;
    this._transport.onmessage = null;
    this._transport.onclose = null;
    for (const callback of this._callbacks.values())
      callback.reject(rewriteError(callback.error, `Protocol error (${callback.method}): Target closed.`));
    this._callbacks.clear();
    for (const session of this._sessions.values())
      session._onClosed();
    this._sessions.clear();
    this.emit(Events.Connection.Disconnected);
  }

  dispose(): void {
    this._onClose();
    this._transport.close();
  }

  /**
   * @param {Protocol.Target.TargetInfo} targetInfo
   * @return {!Promise<!CDPSession>}
   */
  async createSession(targetInfo: Protocol.Target.TargetInfo): Promise<CDPSession> {
    const {sessionId} = await this.send<Protocol.Target.attachedToTargetPayload>('Target.attachToTarget', {targetId: targetInfo.targetId, flatten: true});
    return this._sessions.get(sessionId);
  }
}

interface CDPSessionOnMessageObject {
    id?: number;
    method: string;
    params: {};
    error: {message: string; data: any};
    result?: any;

}
export class CDPSession extends EventEmitter {
  _connection: Connection;
  _sessionId: string;
  _targetType: string;
  _callbacks: Map<number, ConnectionCallback> = new Map();

  constructor(connection: Connection, targetType: string, sessionId: string) {
    super();
    this._connection = connection;
    this._targetType = targetType;
    this._sessionId = sessionId;
  }

  send<T extends keyof Protocol.CommandParameters>(method: T, params?: Protocol.CommandParameters[T]): Promise<Protocol.CommandReturnValues[T]> {
    if (!this._connection)
      return Promise.reject(new Error(`Protocol error (${method}): Session closed. Most likely the ${this._targetType} has been closed.`));

    const id = this._connection._rawSend({
      sessionId: this._sessionId,
      method,
      /* TODO(jacktfranklin@): once this Firefox bug is solved
       * we no longer need the `|| {}` check
       * https://bugzilla.mozilla.org/show_bug.cgi?id=1631570
       */
      params: params || {}
    });

    return new Promise((resolve, reject) => {
      this._callbacks.set(id, {resolve, reject, error: new Error(), method});
    });
  }

  _onMessage(object: CDPSessionOnMessageObject): void {
    if (object.id && this._callbacks.has(object.id)) {
      const callback = this._callbacks.get(object.id);
      this._callbacks.delete(object.id);
      if (object.error)
        callback.reject(createProtocolError(callback.error, callback.method, object));
      else
        callback.resolve(object.result);
    } else {
      assert(!object.id);
      this.emit(object.method, object.params);
    }
  }

  async detach(): Promise<void> {
    if (!this._connection)
      throw new Error(`Session already detached. Most likely the ${this._targetType} has been closed.`);
    await this._connection.send('Target.detachFromTarget',  {sessionId: this._sessionId});
  }

  _onClosed(): void {
    for (const callback of this._callbacks.values())
      callback.reject(rewriteError(callback.error, `Protocol error (${callback.method}): Target closed.`));
    this._callbacks.clear();
    this._connection = null;
    this.emit(Events.CDPSession.Disconnected);
  }
}

/**
 * @param {!Error} error
 * @param {string} method
 * @param {{error: {message: string, data: any}}} object
 * @return {!Error}
 */
function createProtocolError(error: Error, method: string, object: { error: { message: string; data: any}}): Error {
  let message = `Protocol error (${method}): ${object.error.message}`;
  if ('data' in object.error)
    message += ` ${object.error.data}`;
  return rewriteError(error, message);
}

/**
 * @param {!Error} error
 * @param {string} message
 * @return {!Error}
 */
function rewriteError(error: Error, message: string): Error {
  error.message = message;
  return error;
}