// ==UserScript==
// @name        StumbleOut
// @version     2
// @author      raina
// @namespace   raina
// @description Breaks the original link out of StumbleUpon frames. Now with mutation observers!
// @license     http://www.gnu.org/licenses/gpl-3.0.txt
// @include     http://www.stumbleupon.com/su/*
// @run-at      document-start
// @grant       none
// @downloadURL none
// ==/UserScript==
(function() {
	"use strict";

	var link, iframe;

	// Method 1: Actual link is appended to URL, get it and go.
	var method1 = function() {
		window.location.href = link;
	};


	// Method 2: Dig link from iframe after page has loaded. Probably deprecated on SU's part but flows naturally to Method 3.
	var method2 = function() {
		digger();
		if (iframe !== undefined && iframe) {
			window.location.href = iframe.src;
		} else if ("complete" === document.readyState) {
			method3();
		}
	};

	
	// Method 3: Dig link from iframe after web app reports having loaded.
	var method3 = function() {
		var target = document.body;
		var observer = new MutationObserver(function (mutations) {
			mutations.forEach(function (mutation) {
				if ("class" === mutation.attributeName) {
					digger();
					if (iframe !== undefined && iframe) {
						window.location.href = iframe.src;
						observer.disconnect();
					}
				}
			});
		});
		var config = {attributes: true};
		observer.observe(target, config);
	};


	var digger = function() {
		if (iframe === undefined || !iframe) {
			iframe = document.querySelector('.stumble-frame');
		}
	};


	if (window.self === window.top) {
		link = window.location.href.replace(/www\.stumbleupon\.com\/su\/[^\/]*(\/[^\/]*:[^\/]*)?\//, '').replace(/\/#?$/, '');
		if (window.location.href !== link && /^https?:\/\/[\d\w]/.test(link)) {
			method1();
		} else {
			document.addEventListener("readystatechange", method2, false);
		}
	}
}());