/*global window */

/* Demonstration of cross-domain security workaround
   by Philip Hutchison, October 2010
   MIT-style license. Use at your own risk.
   This example's code can be made much more concise, but I'm using long form for clarity in the example
   See explanation at http://pipwerks.com/2010/10/17/iframes-and-cross-domain-security-part-3/
*/

//Returns boolean indicating whether parent frame is accessible
function isSameDomain(){
    
    //Using try/catch to check for top.location so we don't throw a JS error
    try {
        return !!top.location.href;
    } catch (e){
        return false;
    }
    
}


function useProxy(msg){
    
    //var 'msg' will be sent to proxy HTML file via a querystring.
    //This function will prep the string, then send to proxy 

    var querystring = window.location.href.split("?")[1] || false,
        id = "proxyframe", //The name of the frame
        proxy = frames[id], //Look for existing frame with name "proxyframe"
        url_array,
        root = "",
		pairs,
		url;

    if(!querystring || !msg){ return false; }
    

    // --- Prep/clean up string ---
    
    //Encode any question marks since they're reserved for querystrings
    msg = msg.replace(/\?/gi, "%3F");
    
    //URI encode the entire string
    msg = encodeURI(msg);
    
    
    // --- Send to proxy via querystring ---

    //First we must determine what domain is hosting the proxy file
    //by examining the querystring for our custom 'root' parameter
        
    //Ensure all ampersands are single (not entities) so we can split using "&"
    querystring = querystring.replace(/&/g, "&");    
    pairs = querystring.split("&");

    //Loop through the pairs.
    for(var i=0; i < pairs.length; i++){

        if(pairs[i].indexOf("root=") !== -1){

            //Extract the value from the string by replacing the
            //identifier/assignment portion of the string with nothing ""
            root = pairs[i].replace("root=", "");    
            
            if(root !== ""){
                
                //a root parameter was found. decode it.
                root = decodeURI(root);
                
                //replace parent page filename in root parameter
                //with proxy filename and querystring
                url_array = root.split("/");                
                url_array[url_array.length -1] = "proxy.html?msg=" +msg;
                
                //Set new URL
                url = url_array.join("/");                
            
            }
            
            break; //We only care about the 'root' parameter
            
        }

    }
    
    //If the proxy iframe has already been created, use it
    if(proxy){

        //Redirect to the new URL
        proxy.location.href = url;

    //else create the proxy iframe
    } else {

        var iframe = document.createElement("iframe");
        iframe.id = id;
        iframe.name = id;
        iframe.src = url;
        iframe.style.display = "none";
        document.body.appendChild(iframe);

    }
    
}


function sendMessage(){

    var msg = document.getElementById("message").value;

    //If domains match, no need for proxy workaround.
    if(parent && isSameDomain()){
    
        //Invoke parent's JavaScript directly
        top.showMessage(msg);
    
    } else {
        
        //Security restrictions prevent us from communicating
        //directly with parent. Must use proxy instead.
        useProxy(msg);
        
    }

    return false;

}