/*!
* JS Redirection Mobile
*
* Copyright (c) 2010 Sebastiano Armeli-Battana (http://sebarmeli.com)
* MIT Licensed: http://www.opensource.org/licenses/mit-license.php
* @link http://github.com/sebarmeli/JS-Redirection-Mobile-Site/
*/

/*
* This version is exactly the same as redirection_mobile.js, but it's an anonymous self-executing
* function, and it's using the default values for param ("isStandardSite"), mobile_prefix("m"),
* and cookie_hour(1). In this way you can drop this file on your web server with o configuration
*
* @author Sebastiano Armeli-Battana
* @version 0.3
*
*/

/*globals window, redirection_mobile, document, navigator, location */
(function(window, document, navigator) {

  // Helper function
  var addTimeToDate = function(msec) {

    // Get the current date
    var exdate = new Date();

    // Add time to the date
    exdate.setTime(exdate.getTime() + msec);

    //Return the new Date
    return exdate;

  };

  // Retrieve the User Agent of the browser
  var agent = navigator.userAgent.toLowerCase(),

    // param value or default value
    param = "isStandardSite",

    // Constant
    TRUE = "true",

    // "m" is the default mobile hostname prefix
    mobile_prefix = "m",

    // URL host of incoming request
      host = document.location.host,

    // Compose the mobile hostname
      mobile_host = host + "/" + mobile_prefix,

    // Expiry hours for cookie
    cookie_hours = 1,

    // Check if the UA is a mobile one (iphone, ipod, ipad, android, blackberry)
    isUAMobile =!!(agent.match(/(iPhone|iPod|iPad|blackberry|android|htc|kindle|lg|midp|mmp|mobile|nokia|opera mini|palm|pocket|psp|sgh|smartphone|symbian|treo mini|Playstation Portable|SonyEricsson|Samsung|MobileExplorer|PalmSource|Benq|Windows Phone)/i));

  // Check if the referrer was a mobile page of the site
  // (in that case we need to set a variable in the sessionStorage or in the cookie)
  if (document.referrer.indexOf(mobile_host) >= 0) {
    if (window.sessionStorage) {
      window.sessionStorage.setItem(param, TRUE);
    } else {
      document.cookie = param + "=" + TRUE + ";expires="+
                        addTimeToDate(3600*1000*cookie_hours).toUTCString();
    }
  }

  // Check if the sessionStorage contain the parameter
  var isSessionStorage = (window.sessionStorage) ?
              (window.sessionStorage.getItem(param) === TRUE) :
               false,

    // Check if the Cookie has been set up
    isCookieSet = document.cookie ?
            (document.cookie.indexOf(param) >= 0) :
              false;

  // Check that User Agent is mobile, cookie is not set or value in the sessionStorage not present
  if (isUAMobile && !(isCookieSet || isSessionStorage)) {
     document.location.href = document.location.protocol + "//" + mobile_host;
  }

}(window, document, navigator));