// Copyright 2007 Google Inc.
// All Rights Reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in
//    the documentation and/or other materials provided with the
//    distribution.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE. 

/**
 * @fileoverview Detection of JScript version.
 *
 */


goog.provide('goog.userAgent.jscript');

goog.require('goog.string');


/**
 * @define {boolean} True if it is known at compile time that the runtime
 *     environment will not be using JScript.
 */
goog.userAgent.jscript.ASSUME_NO_JSCRIPT = false;


/**
 * Initializer for goog.userAgent.jscript.  Detects if the user agent is using
 * Microsoft JScript and which version of it.
 *
 * This is a named function so that it can be stripped via the jscompiler
 * option for stripping types.
 * @private
 */
goog.userAgent.jscript.init_ = function() {
  /**
   * @type {boolean}
   * @private
   */
  goog.userAgent.jscript.DETECTED_HAS_JSCRIPT_ = false;

  /**
   * @type {string}
   * @private
   */
  goog.userAgent.jscript.DETECTED_VERSION_ = '0';

  if ('ScriptEngine' in goog.global) {
    goog.userAgent.jscript.DETECTED_HAS_JSCRIPT_ =
        goog.global['ScriptEngine']() == 'JScript';
    if (goog.userAgent.jscript.DETECTED_HAS_JSCRIPT_) {
      goog.userAgent.jscript.DETECTED_VERSION_ =
          goog.global['ScriptEngineMajorVersion']() + '.' +
          goog.global['ScriptEngineMinorVersion']() + '.' +
          goog.global['ScriptEngineBuildVersion']();
    }
  }
};

if (!goog.userAgent.jscript.ASSUME_NO_JSCRIPT) {
  goog.userAgent.jscript.init_();
}

/**
 * Whether we detect that the user agent is using Microsoft JScript.
 * @type {boolean}
 */
goog.userAgent.jscript.HAS_JSCRIPT = goog.userAgent.jscript.ASSUME_NO_JSCRIPT ?
    false : goog.userAgent.jscript.DETECTED_HAS_JSCRIPT_;


/**
 * The installed version of JScript.
 * @type {string}
 */
goog.userAgent.jscript.VERSION = goog.userAgent.jscript.ASSUME_NO_JSCRIPT ?
    '0' : goog.userAgent.jscript.DETECTED_VERSION_;


/**
 * Whether the installed version of JScript is as new or newer than a given
 * version.
 * @param {string} version The version to check.
 * @return {boolean} Whether the installed version of JScript is as new or
 *     newer than the given version.
 */
goog.userAgent.jscript.isVersion = function(version) {
  return goog.string.compareVersions(goog.userAgent.jscript.VERSION,
                                     version) >= 0;
};