utils.js

/*
 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree.
 */
/* eslint-env node */
'use strict';

let logDisabled_ = true;
let deprecationWarnings_ = true;

/**
 * Extract browser version out of the provided user agent string.
 *
 * @param {!string} uastring userAgent string.
 * @param {!string} expr Regular expression used as match criteria.
 * @param {!number} pos position in the version string to be returned.
 * @return {!number} browser version.
 */
export function extractVersion(uastring, expr, pos) {
  const match = uastring.match(expr);
  return match && match.length >= pos && parseInt(match[pos], 10);
}

// Wraps the peerconnection event eventNameToWrap in a function
// which returns the modified event object (or false to prevent
// the event).
export function wrapPeerConnectionEvent(window, eventNameToWrap, wrapper) {
  if (!window.RTCPeerConnection) {
    return;
  }
  const proto = window.RTCPeerConnection.prototype;
  const nativeAddEventListener = proto.addEventListener;
  proto.addEventListener = function(nativeEventName, cb) {
    if (nativeEventName !== eventNameToWrap) {
      return nativeAddEventListener.apply(this, arguments);
    }
    const wrappedCallback = (e) => {
      const modifiedEvent = wrapper(e);
      if (modifiedEvent) {
        if (cb.handleEvent) {
          cb.handleEvent(modifiedEvent);
        } else {
          cb(modifiedEvent);
        }
      }
    };
    this._eventMap = this._eventMap || {};
    if (!this._eventMap[eventNameToWrap]) {
      this._eventMap[eventNameToWrap] = new Map();
    }
    this._eventMap[eventNameToWrap].set(cb, wrappedCallback);
    return nativeAddEventListener.apply(this, [nativeEventName,
      wrappedCallback]);
  };

  const nativeRemoveEventListener = proto.removeEventListener;
  proto.removeEventListener = function(nativeEventName, cb) {
    if (nativeEventName !== eventNameToWrap || !this._eventMap
        || !this._eventMap[eventNameToWrap]) {
      return nativeRemoveEventListener.apply(this, arguments);
    }
    if (!this._eventMap[eventNameToWrap].has(cb)) {
      return nativeRemoveEventListener.apply(this, arguments);
    }
    const unwrappedCb = this._eventMap[eventNameToWrap].get(cb);
    this._eventMap[eventNameToWrap].delete(cb);
    if (this._eventMap[eventNameToWrap].size === 0) {
      delete this._eventMap[eventNameToWrap];
    }
    if (Object.keys(this._eventMap).length === 0) {
      delete this._eventMap;
    }
    return nativeRemoveEventListener.apply(this, [nativeEventName,
      unwrappedCb]);
  };

  Object.defineProperty(proto, 'on' + eventNameToWrap, {
    get() {
      return this['_on' + eventNameToWrap];
    },
    set(cb) {
      if (this['_on' + eventNameToWrap]) {
        this.removeEventListener(eventNameToWrap,
          this['_on' + eventNameToWrap]);
        delete this['_on' + eventNameToWrap];
      }
      if (cb) {
        this.addEventListener(eventNameToWrap,
          this['_on' + eventNameToWrap] = cb);
      }
    },
    enumerable: true,
    configurable: true
  });
}

export function disableLog(bool) {
  if (typeof bool !== 'boolean') {
    return new Error('Argument type: ' + typeof bool +
        '. Please use a boolean.');
  }
  logDisabled_ = bool;
  return (bool) ? 'adapter.js logging disabled' :
    'adapter.js logging enabled';
}

/**
 * Disable or enable deprecation warnings
 * @param {!boolean} bool set to true to disable warnings.
 */
export function disableWarnings(bool) {
  if (typeof bool !== 'boolean') {
    return new Error('Argument type: ' + typeof bool +
        '. Please use a boolean.');
  }
  deprecationWarnings_ = !bool;
  return 'adapter.js deprecation warnings ' + (bool ? 'disabled' : 'enabled');
}

export function log() {
  if (typeof window === 'object') {
    if (logDisabled_) {
      return;
    }
    if (typeof console !== 'undefined' && typeof console.log === 'function') {
      console.log.apply(console, arguments);
    }
  }
}

/**
 * Shows a deprecation warning suggesting the modern and spec-compatible API.
 */
export function deprecated(oldMethod, newMethod) {
  if (!deprecationWarnings_) {
    return;
  }
  console.warn(oldMethod + ' is deprecated, please use ' + newMethod +
      ' instead.');
}

/**
 * Browser detector.
 *
 * @return {object} result containing browser and version
 *     properties.
 */
export function detectBrowser(window) {
  // Returned result object.
  const result = {browser: null, version: null};

  // Fail early if it's not a browser
  if (typeof window === 'undefined' || !window.navigator ||
      !window.navigator.userAgent) {
    result.browser = 'Not a browser.';
    return result;
  }

  const {navigator} = window;

  // Prefer navigator.userAgentData.
  if (navigator.userAgentData && navigator.userAgentData.brands) {
    const chromium = navigator.userAgentData.brands.find((brand) => {
      return brand.brand === 'Chromium';
    });
    if (chromium) {
      return {browser: 'chrome', version: parseInt(chromium.version, 10)};
    }
  }

  if (navigator.mozGetUserMedia) { // Firefox.
    result.browser = 'firefox';
    result.version = extractVersion(navigator.userAgent,
      /Firefox\/(\d+)\./, 1);
  } else if (navigator.webkitGetUserMedia ||
      (window.isSecureContext === false && window.webkitRTCPeerConnection)) {
    // Chrome, Chromium, Webview, Opera.
    // Version matches Chrome/WebRTC version.
    // Chrome 74 removed webkitGetUserMedia on http as well so we need the
    // more complicated fallback to webkitRTCPeerConnection.
    result.browser = 'chrome';
    result.version = extractVersion(navigator.userAgent,
      /Chrom(e|ium)\/(\d+)\./, 2);
  } else if (window.RTCPeerConnection &&
      navigator.userAgent.match(/AppleWebKit\/(\d+)\./)) { // Safari.
    result.browser = 'safari';
    result.version = extractVersion(navigator.userAgent,
      /AppleWebKit\/(\d+)\./, 1);
    result.supportsUnifiedPlan = window.RTCRtpTransceiver &&
        'currentDirection' in window.RTCRtpTransceiver.prototype;
  } else { // Default fallthrough: not supported.
    result.browser = 'Not a supported browser.';
    return result;
  }

  return result;
}

/**
 * Checks if something is an object.
 *
 * @param {*} val The something you want to check.
 * @return true if val is an object, false otherwise.
 */
function isObject(val) {
  return Object.prototype.toString.call(val) === '[object Object]';
}

/**
 * Remove all empty objects and undefined values
 * from a nested object -- an enhanced and vanilla version
 * of Lodash's `compact`.
 */
export function compactObject(data) {
  if (!isObject(data)) {
    return data;
  }

  return Object.keys(data).reduce(function(accumulator, key) {
    const isObj = isObject(data[key]);
    const value = isObj ? compactObject(data[key]) : data[key];
    const isEmptyObject = isObj && !Object.keys(value).length;
    if (value === undefined || isEmptyObject) {
      return accumulator;
    }
    return Object.assign(accumulator, {[key]: value});
  }, {});
}

/* iterates the stats graph recursively. */
export function walkStats(stats, base, resultSet) {
  if (!base || resultSet.has(base.id)) {
    return;
  }
  resultSet.set(base.id, base);
  Object.keys(base).forEach(name => {
    if (name.endsWith('Id')) {
      walkStats(stats, stats.get(base[name]), resultSet);
    } else if (name.endsWith('Ids')) {
      base[name].forEach(id => {
        walkStats(stats, stats.get(id), resultSet);
      });
    }
  });
}

/* filter getStats for a sender/receiver track. */
export function filterStats(result, track, outbound) {
  const streamStatsType = outbound ? 'outbound-rtp' : 'inbound-rtp';
  const filteredResult = new Map();
  if (track === null) {
    return filteredResult;
  }
  const trackStats = [];
  result.forEach(value => {
    if (value.type === 'track' &&
        value.trackIdentifier === track.id) {
      trackStats.push(value);
    }
  });
  trackStats.forEach(trackStat => {
    result.forEach(stats => {
      if (stats.type === streamStatsType && stats.trackId === trackStat.id) {
        walkStats(result, stats, filteredResult);
      }
    });
  });
  return filteredResult;
}