/**
 * 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.
 */

const {helper} = require('./helper');
const Page = require('./Page');
const EventEmitter = require('events');

class Browser extends EventEmitter {
  /**
   * @param {!Connection} connection
   * @param {boolean} ignoreHTTPSErrors
   * @param {function():Promise=} closeCallback
   */
  constructor(connection, ignoreHTTPSErrors, closeCallback) {
    super();
    this._ignoreHTTPSErrors = ignoreHTTPSErrors;
    this._screenshotTaskQueue = new TaskQueue();
    this._connection = connection;
    this._closeCallback = closeCallback || new Function();
  }

  /**
   * @return {string}
   */
  wsEndpoint() {
    return this._connection.url();
  }

  /**
   * @return {!Promise<!Page>}
   */
  async newPage() {
    const {targetId} = await this._connection.send('Target.createTarget', {url: 'about:blank'});
    const client = await this._connection.createSession(targetId);
    return await Page.create(client, this._ignoreHTTPSErrors, this._screenshotTaskQueue);
  }

  /**
   * @return {!Promise<string>}
   */
  async version() {
    const version = await this._connection.send('Browser.getVersion');
    return version.product;
  }

  async close() {
    this._connection.dispose();
    await this._closeCallback.call(null);
  }
}

module.exports = Browser;
helper.tracePublicAPI(Browser);

class TaskQueue {
  constructor() {
    this._chain = Promise.resolve();
  }

  /**
   * @param {function()} task
   * @return {!Promise}
   */
  postTask(task) {
    const result = this._chain.then(task);
    this._chain = result.catch(() => {});
    return result;
  }
}