// Copyright 2016 The Closure Library Authors. 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.

/**
 * @fileoverview Methods to verify IE versions.
 * TODO(johnlenz): delete this remove this file on the experiment is complete.
 */
goog.provide('goog.labs.useragent.verifier');


/** @const */
goog.labs.useragent.verifier.NOT_IE = 0;


/**
 * Detect the the current IE version using runtime behavior, returns 0
 * if a version of IE is not detected.
 * @return {number}
 */
goog.labs.useragent.verifier.detectIeVersionByBehavior = function() {
  if (document.all) {
    if (!document.compatMode) {
      return 5;
    }
    if (!window.XMLHttpRequest) {
      return 6;
    }
    if (!document.querySelector) {
      return 7;
    }
    if (!document.addEventListener) {
      return 8;
    }
    if (!window.atob) {
      return 9;
    }

    return 10;
  }
  if (!(window.ActiveXObject) && 'ActiveXObject' in window) {
    return 11;
  }

  return goog.labs.useragent.verifier.NOT_IE;
};


/**
 * Detect the the current IE version using MSIE version presented in the
 * user agent string (This will not detected IE 11 which does not present a
 * MSIE version), or zero if IE is not detected.
 * @return {number}
 */
goog.labs.useragent.verifier.detectIeVersionByNavigator = function() {
  var ua = navigator.userAgent.toLowerCase();
  if (ua.indexOf('msie') != -1) {
    var value = parseInt(ua.split('msie')[1], 10);
    if (typeof value == 'number' && !isNaN(value)) {
      return value;
    }
  }

  return goog.labs.useragent.verifier.NOT_IE;
};


/**
 * Correct the actual IE version based on the Trident version in the user agent
 * string.  This adjusts for IE's "compatiblity modes".
 * @return {number}
 */
goog.labs.useragent.verifier.getCorrectedIEVersionByNavigator = function() {
  var ua = navigator.userAgent;
  if (/Trident/.test(ua) || /MSIE/.test(ua)) {
    return goog.labs.useragent.verifier.getIEVersion_(ua);
  } else {
    return goog.labs.useragent.verifier.NOT_IE;
  }
};


/**
 * Get corrected IE version, see goog.labs.userAgent.browser.getIEVersion_
 *
 * @param {string} userAgent the User-Agent.
 * @return {number}
 * @private
 */
goog.labs.useragent.verifier.getIEVersion_ = function(userAgent) {
  // IE11 may identify itself as MSIE 9.0 or MSIE 10.0 due to an IE 11 upgrade
  // bug. Example UA:
  // Mozilla/5.0 (MSIE 9.0; Windows NT 6.1; WOW64; Trident/7.0; rv:11.0)
  // like Gecko.
  var rv = /rv: *([\d\.]*)/.exec(userAgent);
  if (rv && rv[1]) {
    return Number(rv[1]);
  }

  var msie = /MSIE +([\d\.]+)/.exec(userAgent);
  if (msie && msie[1]) {
    // IE in compatibility mode usually identifies itself as MSIE 7.0; in this
    // case, use the Trident version to determine the version of IE. For more
    // details, see the links above.
    var tridentVersion = /Trident\/(\d.\d)/.exec(userAgent);
    if (msie[1] == '7.0') {
      if (tridentVersion && tridentVersion[1]) {
        switch (tridentVersion[1]) {
          case '4.0':
            return 8;
          case '5.0':
            return 9;
          case '6.0':
            return 10;
          case '7.0':
            return 11;
        }
      } else {
        return 7;
      }
    } else {
      return Number(msie[1]);
    }
  }
  return goog.labs.useragent.verifier.NOT_IE;
};