/*!
* JS Redirection Mobile
*
* Developed by
* Sebastiano Armeli-Battana (@sebarmeli) - http://www.sebastianoarmelibattana.com
* Dual licensed under the MIT or GPL Version 3 licenses.
*/
/*
  Copyright (c) 2011 Sebastiano Armeli-Battana (http://www.sebastianoarmelibattana.com)

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
* This script will cover a basic scenario of full JS mobile redirection.
* The user will be redirected to the mobile version of the site (home page)
* if it's trying to access the site from a mobile device. This check is
* mainly done checking the User-Agent string. 
* The mobile URL will be obtained appending a prefix (default is "m") to 
* the hostname of the current URL. It's used a naked domain to avoid conflict with
* www.
* 
* In some cases the user needs to be redirected to the Desktop version of the site 
* from a mobile device. This happens when the user clicks on a link such as "Go to full site"
* or when there is a specific parameter in the querystring.
*
* In that case a new key/value in sessionStorage (for modern browsers) 
* will be set and until the user doesn't close browser window or tab it will access
* to the desktop version from a mobile device. There is a fallback for old browsers that
* don't support sessionStorage, and it will use a cookie. The cookie will expiry in one hour 
* (default value) or you configure the expiry time.
* 
* To use this function, you need to call it as SA.redirection_mobile(config);
* E.g. SA.redirection_mobile ({noredirection_param : "noredirection", mobile_prefix : "mobile", cookie_hours : "2" })
* or
* E.g. SA.redirection_mobile ({mobile_url : "mobile.whatever.com/example", mobile_sheme : "https" })
* or
* E.g. SA.redirection_mobile ({mobile_prefix : "mobile"})
* or
* E.g. SA.redirection_mobile ({mobile_prefix : "mobile", mobile_scheme : "https", redirection_paramName : "modile_redirect"})
* or
* E.g. SA.redirection_mobile ({mobile_url : "mobile.whatever.com/example", tablet_redirection : "true"})
* or
* E.g. SA.redirection_mobile ({{mobile_url : "mobile.whatever.com/example", beforeredirection_callback : (function(){alert('2')}) }})
* or
* E.g. SA.redirection_mobile ({{mobile_url : "mobile.whatever.com", tablet_url : "tablet.whatever.com")
*
*
* @link http://github.com/sebarmeli/JS-Redirection-Mobile-Site/
* @author Sebastiano Armeli-Battana
* @version 0.9.5
* @date 25/07/2011 
* 
*/
  
/*globals window,document, navigator, SA */
if (!window.SA) {window.SA = {};}

/*
* @param configuration object containing three properties:
*      - mobile_prefix : prefix appended to the hostname (such as "m" to redirect to "m.domain.com")
*      - mobile_url : mobile url to use for the redirection (such as "mobile.whatever.com" to redirect to "whatever.com" )
*      - mobile_scheme : url scheme (http/https) of the mobile site domain
*      - cookie_hours : number of hours the cookie needs to exist after redirection to desktop site
*      - noredirection_param : parameter to pass in the querystring of the URL to avoid the redirection (the value must be equal to "true").
*        It's also the name of the item in the localStorage (or cookie name) to avoid mobile
*        redirection. Default value is "noredirection". Eg: http://domain.com?noredirection=true
*      - tablet_redirection : boolean value that enables/disables(default) the redirection for tablet such as iPad, Samsung Galaxy Tab, Kindle or Motorola Xoom. - Default:false
*        Default Url for redirection will be the same as the one for mobile devices.
*      - tablet_url : url to use for the redirection in case user is using a tablet to access the site
*      - keep_path : boolean to determine if the destination url needs to keep the path from the original url
*      - keep_query : boolean to determine if the destination url needs to keep the querystring from the original url
*      - beforeredirection_callback : callback launched before the redirection happens
*/
SA.redirection_mobile = function(configuration) {

  // Helper function for adding time to the current date
  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;

  };

  // Helper function for getting a value from a parameter in the querystring
  var getQueryValue = function(param) {

    if (!param) {
      return;
    }

    var querystring = document.location.search,
      queryStringArray = querystring && querystring.substring(1).split("&"),
      i = 0,
      length = queryStringArray.length;

    for (; i < length; i++) {
      var token = queryStringArray[i],
        firstPart = token && token.substring(0, token.indexOf("="));
      if (firstPart === param ) {
        return token.substring(token.indexOf("=") + 1, token.length);
      }
    }

  };
        
  // Retrieve the User Agent of the browser
  var agent = navigator.userAgent.toLowerCase(),
  
    // Constants
    FALSE = "false",
    TRUE = "true",

    // configuration object
    config = configuration || {},
  
    // parameter to pass in the URL to avoid the redirection
    redirection_param = config.noredirection_param || "noredirection",
    
    // prefix appended to the hostname
    mobile_prefix = config.mobile_prefix || "m",
    
    // new url for the mobile site domain 
    mobile_url = config.mobile_url,
    
    // protocol for the mobile site domain 
    mobile_protocol = config.mobile_scheme ?
      config.mobile_scheme + ":" :
        document.location.protocol,
    
    // URL host of incoming request
    host = document.location.host,

    // value for the parameter passed in the URL to avoid the redirection
    queryValue = getQueryValue(redirection_param),

    // Compose the mobile hostname considering "mobile_url" or "mobile_prefix" + hostname
    mobile_host = mobile_url ||
      (mobile_prefix + "." + 
        (!!host.match(/^www\./i) ?
          host.substring(4) : 
            host)),

    // Expiry hours for cookie
    cookie_hours = config.cookie_hours || 1,
    
    // Parameters to determine if the pathname and the querystring need to be kept
    keep_path = config.keep_path || false,
    keep_query = config.keep_query || false,

    // new url for the tablet site domain 
    tablet_host = config.tablet_url || mobile_host,
    
    // Check if the UA is a mobile one (iphone, ipod, android, blackberry)
    isUAMobile =!!(agent.match(/(iPhone|iPod|blackberry|android 0.5|htc|lg|midp|mmp|mobile|nokia|opera mini|palm|pocket|psp|sgh|smartphone|symbian|treo mini|Playstation Portable|SonyEricsson|Samsung|MobileExplorer|PalmSource|Benq|Windows Phone|Windows Mobile|IEMobile|Windows CE|Nintendo Wii)/i));


  // Check if the referrer was a mobile page (probably the user clicked "Go to full site") or in the 
  // querystring there is a parameter to avoid the redirection such as "?mobile_redirect=false"
  // (in that case we need to set a variable in the sessionStorage or in the cookie)
  if (document.referrer.indexOf(mobile_host) >= 0 || queryValue === TRUE ) {

    if (window.sessionStorage) {
      window.sessionStorage.setItem(redirection_param, TRUE);
    } else {
      document.cookie = redirection_param + "=" + TRUE + ";expires="+
        addTimeToDate(3600*1000*cookie_hours).toUTCString();
    }
  }

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

    // Check if the Cookie has been set up
    isCookieSet = document.cookie ? 
      (document.cookie.indexOf(redirection_param) >= 0) :
        false;
  
  // Check if the device is a Tablet such as iPad, Samsung Tab, Motorola Xoom or Amazon Kindle
  if (!!(agent.match(/(iPad|SCH-I800|xoom|kindle)/i))) {

    // Check if the redirection needs to happen for iPad
    var isUATablet = (config.tablet_redirection === TRUE || !!config.tablet_url) ? true : false;
    isUAMobile = false;
  }

  // Check that User Agent is mobile, cookie is not set or value in the sessionStorage not present
  if ((isUATablet || isUAMobile) && !(isCookieSet || isSessionStorage)) {

    // Callback call
    if (config.beforeredirection_callback) {
      if (!config.beforeredirection_callback.call(this)) {
        return;
      }
    }
    
    var path_query = "";
    
    if(keep_path) { 
      path_query += document.location.pathname;
    }
    
    if (keep_query) {
      path_query += document.location.search;
    }
    
    if (isUATablet){
      document.location.href = mobile_protocol + "//" + tablet_host + path_query;
    } else if (isUAMobile) {
      document.location.href = mobile_protocol + "//" + mobile_host + path_query;
    }
    
  } 
};