/*!
* 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 ({redirection_paramName : "modile_redirect", 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", mobile_scheme : "https"})
* 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')}) }})
*
*
* @link http://github.com/sebarmeli/JS-Redirection-Mobile-Site/
* @author Sebastiano Armeli-Battana
* @version 0.8.5
* @date 02/04/2011
*
*/

/*globals window,document, navigator, SA */
if (!window.SA) {window.SA = {};}

/*
* @param config 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 "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
* - redirection_paramName : parameter to pass in the querystring of the URL to avoid the redirection (the value must be equal to "false").
* It's also the name of the item in the localStorage (or cookie name) to avoid mobile
* redirection. Default value is "mobile_redirect". Eg: http://domain.com?mobile_redirect=false
* - tablet_redirection : boolean value that enables/disables(default) the redirection for tablet such as iPad, Samsung Galaxy Tab, Kindle or Motorola Xoom. - Default:false
* - beforeredirection_callback : callback launched before the redirection happens
*/
SA.redirection_mobile = function(config) {

// 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 = config || {};

// parameter to pass in the URL to avoid the redirection
redirection_param = config.redirection_paramName || "mobile_redirect",

// 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,

// 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 === FALSE ) {

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

// Check if the sessionStorage contain the parameter
var isSessionStorage = (window.sessionStorage) ?
(window.sessionStorage.getItem(redirection_param) === FALSE) :
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
(config.tablet_redirection === TRUE) ? isUAMobile = true : isUAMobile = false;

}

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

// Callback call
if (config.beforeredirection_callback) {
if (!config.beforeredirection_callback.call(this)) {
return;
}
}

document.location.href = mobile_protocol + "//" + mobile_host;
}
};