// ==UserScript==
// @name           FaviconizeTheWeb
// @description    Adds a favicon for the website next to every external link on the page.  Clearly shows when you will be leaving the current site, and where you will be going!  (Unfortunately making links longer than expected can result in unwanted overflow on various websites.  For example, Google header bar!)
// @downstreamURL  http://userscripts.org/scripts/source/60833.user.js
// @namespace      FTW
// @include        *
//// Awesome websites already provide favicons:
// @exclude        http://www.delicious.com/search*
// @exclude        https://www.delicious.com/search*
// @exclude        http://duckduckgo.com/*
// @exclude        https://duckduckgo.com/*
//// Not possible due to content policy
// @exclude        https://github.com/*
//// Causes login dialogs to open!
// @exclude        http://www.jobs.ac.uk/*
// @version        1.5.6
// @downloadURL https://update.greasyfork.icu/scripts/7665/FaviconizeTheWeb.user.js
// @updateURL https://update.greasyfork.icu/scripts/7665/FaviconizeTheWeb.meta.js
// ==/UserScript==
// Based on FaviconizeGoogle.



// == Config == //

var placeFaviconAfter = false;
var placeFaviconInsideLink = false;
var scaleIcon = 0.75;

var initialDelay = 1000;
var delayIncrement = 5; // after 200 links the delay between batches will be 1 second
var batchSize = 10;

var alwaysUseGoogle = false;   // Uses a google service to load the favicon images



if (!alwaysUseGoogle) {
	// We can speed up if we are requesting from multiple sites
	initialDelay = 100;
	delayIncrement = 5;
}

if (document.location.host.indexOf(".google.") >= 0) {
	scaleIcon = 1.0;
	// return;   // REMOVE THIS TO RUN ON GOOGLE!
	//// For search results pages with late loading results via AJAX.
	initialDelay = 1000;   // Pause to wait for AJAX results (e.g. going back to a URL where search terms were modified and updated in the # part).
	// TODO: The proper way to deal with AJAX is to watch for DOMNodeInserted event.
}



// CHANGELOG
// 2012-10.15  Applied CSS rules to elements, to override more specific page rules.



// BUG: When a link only just fits inside its container, adding the favicon may
// cause the container to grow or overflow or wrap!  This can look very messy
// if the site uses a strict CSS layout.  We have a fix for Google; can we
// detect in general when this fix should be employed?  (AVOID_OVERFLOW)



// == Library Functions == //

if (typeof GM_log == 'undefined' && typeof console != 'undefined' && typeof console.log == 'function') {
	GM_log = function(x) {
		console.log(x);
	};
}

function setBatchTimeout(callbackFn,delay) {
	// Rather dodgy implementation of batch processing ;)
	if (Math.random()>(1.0/batchSize)) // 0.0 locks up the browser on large pages with many favicons
		callbackFn();
	else
		setTimeout(callbackFn,delay);
}

function getElementsByTagNameAndClassName(tN,cN) {
	return filterListBy( document.getElementsByTagName(tN), function(x){ return x.className==cN } );
}

function getElementsByClassName(cN) {
	return getElementsByTagNameAndClassName("*",cN);
}

function checkAncestorsForId(node, id) {
	while (node = node.parentNode) {
		if (node.id == id) {
			return true;
		}
	}
	return false;
}

function filterListBy(l,c) {
	var ret = [];
	for (var i=0;i<l.length;i++) {
		var it = l[i];
		if (c(it)) {
			ret.push(it);
		}
	}
	return ret;
}

var currentDelay = 0;
function iterateAndDo(list,iterationFn) {
	var i = 0;
	function doOne() {
		if (i < list.length) {
			iterationFn(list[i]);
			i++;
			currentDelay += delayIncrement;
			setBatchTimeout(doOne,currentDelay);
		} else {
			GM_log("Added "+i+" favicons to "+document.title+".");
		}
	}
	doOne();
}



// == Main == //

function createFaviconFor(url) {

	var protocol = url.replace(/^([^\/]*):\/\/.*/,'$1');
	var host = url.replace(/^[^\/]*:\/\//,'').replace(/\/.*$/,'');
	// if (host == document.location.host) {
		// return null;
	// }
	var img = document.createElement('IMG');
	// img.src = 'http://'+host+'/favicon.ico';

	var imageExtensions = ( alwaysUseGoogle ? [] : ['ico','png','gif','jpg'] );
	function tryExtension(evt) {
		var ext = imageExtensions.shift();
		// Use protocol (http/https) of current page, to avoid mixed-content warnings/failures.
		var protocol = document.location.protocol.replace(/:$/, '');
		if (ext) {
			img.src = protocol + '://' + host + '/favicon.' + ext;
		} else {
			if (!alwaysUseGoogle) {
				img.title = "Failed to find favicon for " + host;
			}
			img.src = protocol + '://www.google.com/s2/favicons?domain=' + host; // Google's cache will sometimes provide a favicon we would have missed, e.g. if the site uses .png instead of .ico.  Thanks to NV for suggesting this, and to Google.
			// img.src = protocol + '://g.etfv.co/' + protocol + "://" + host; // As suggested by decembre
			// @consider We could also generate an md5sum and request a gravatar, which might simply allow human recognition of repeats.
			// img.removeEventListener('error',tryExtension,true);
			img.onerror = undefined;
		}
		if (evt) {
			// Will this stop the browser from displaying the error?
			evt.preventDefault();
			return false;
			// Answer: NO!
		}
	}
	// img.addEventListener('error',tryExtension,true);
	img.onerror = tryExtension;
	tryExtension();

	img.title = ''+host;
	// img.width = 16*scaleIcon;
	// img.height = 16*scaleIcon;
	img.className = 'ftwFavicon';
	// img.style.border = 0;
	// Favicon image elements are hidden until they have fully loaded
	// img.style.display = 'none';
	img.addEventListener('load',function(){ img.style.display = ''; },false);
	return img;
}



var count = 0;

var lastURL = null;

function checkLink(link) {

	if (!link.href) {
		return;
	}
	// Skip relative and same-host links (there is no host on file:/// pages):
	if (link.href.match(/^[/]/) || (document.location.host && link.href.match("://"+document.location.host))) {
		return;
	}
	// Skip Javascript links and relative (same-page) anchors
	if ( link.href.match(/^#/) || link.href.match(/^javascript:/)
		// Sometimes .href is the full URL whereas .getAttrib starts just #
		|| link.getAttribute("href").match(/^#/) || link.getAttribute("href").match(/^javascript:/)
	) {
		return;
	}
	// Do not faviconize links which contain (or are only) an image
	if (link.getElementsByTagName("IMG").length > 0 || link.getElementsByTagName("SVG").length > 0) {
		return;
	}
	if (link.protocol === "file:") {
		return;
		// We might be able to guess the real hostname from the path and do a web request for the favicon, or search the folders above for a favicon file?
	}
	// StackExchange's "Hot Network Questions" links already have favicons!
	if (link.previousSibling && link.previousSibling.classList && link.previousSibling.classList.contains('favicon')) {
		return;
	}

	// Let's not create a duplicate favicon if the page offers the same link with two different <A>s:
	var sameAsLast = (link.href == lastURL);
	if (sameAsLast)
		return;
	// TODO CONSIDER: Instead of that, just never add the same favicon twice in a row, i.e. same host.
	// But optional.  At other times it might be desirable to have both, e.g. in a list of 10 with a few from the same domain.

	lastURL = link.href;

	var img = createFaviconFor(link.href);
	// img.style = getStyleString();
	getStyleString().split(/; */).forEach(function(r){
		var p = r.split(/: */);
		var prop = p[0];
		var val  = p[1];
		var i;
		while ( (i = prop.indexOf("-")) >= 0) {
			prop = prop.substring(0,i) + prop.substring(i+1,i+2).toUpperCase() + prop.substring(i+2);
		}
		// GM_log("img.style["+prop+"] = "+val);
		img.style[prop] = val;
	});
	img.style.display = 'none';
	var loadListener = function(img){return function(){ img.style.display = 'inline'; };}(img);
	img.addEventListener('load',loadListener,false);
	var targetNode = link;
	if (placeFaviconInsideLink) {
		if (placeFaviconAfter) {
			targetNode.appendChild(img);
		} else {
			targetNode.insertBefore(img,targetNode.firstChild);
		}
	} else {
		if (placeFaviconAfter) {
			targetNode.parentNode.insertBefore(img,targetNode.nextSibling);
		} else {
			targetNode.parentNode.insertBefore(img,targetNode);
		}
	}

	// For Delicious.  Their low-detail links have float:left set, so our
	// images appear to their right, unless...
	if (document.location.href.indexOf("delicious")>=0 && /(^|\s)taggedlink($|\s)/.test(link.className)) {
		img.style.float = 'left';
	}

	// AVOID_OVERFLOW
	// Lots of links at the top of Google's search page overflow and look messy.
	if (document.location.host.indexOf(".google.") >= 0) {
		if (checkAncestorsForId(link,"mngb") || checkAncestorsForId(link,"gb")) {
			img.style.float = 'left';
		}
	}

	// If any website puts a border on their images, we want to remove it
	// img.style.border = '0px';

	count++;
	return;

}

function addStyle(css) {
	var style = document.createElement('STYLE');
	style.innerHTML = css;
	document.getElementsByTagName('head')[0].appendChild(style);
}

function getStyleString() {
	var padSide = (placeFaviconAfter?'left':'right');
	// var avoidOverflow = "float: left;"; // AVOID_OVERFLOW TESTING is it always suitable?  Works well on Google search results header links.  Yeah ok it was rubbish.  The favicon for a link in a paragraph appears at the beginning of the paragraph!
	var resetStyles = "display: inline; margin: 0px; padding: 0px; border: 0px; background: none; position: static;";
	var setStyles = "margin-"+padSide+": "+(scaleIcon/3)+"em; opacity: 0.7; width: "+scaleIcon+"em; height: "+scaleIcon+"em; vertical-align: 0em;";
	return resetStyles + " "+ setStyles;
}

function doIt() {

	// GM_log("doIt() was called!");

	//// Unfortunately this can be overridden by more specific page rules.
	//// e.g. ".article .body img" is more specific than ".ftwFavicon"
	// addStyle(".ftwFavicon { "+getStyleString()+" }");
	//// To override that, we put style rules in each element.

	// vertical-align: middle; <-- appears to make alignment worse in Chrome!
	// Settled for vertical-align: 0em; which fits since capital text seem to be about 0.75em tall

	// var links = document.evaluate("//a[@class='l']",document,null,6,null);
	// var links = filterListBy(document.links, function(x){ return x.className=='l'; } );
	// var links = document.links.filter( function(x){ return x.className=='l'; } );
	// var links = getElementsByTagNameAndClassName("A",'l');
	// Allows it to work on any sites:
	// if (links.length == 0)
	var links = document.getElementsByTagName("A");

	// GM_log("Got links = "+links.snapshotLength);

	iterateAndDo(links,checkLink);

}


// doIt();

/* Adding lots of little images to the page can lock up slow browsers a bit, so
 * we wait a bit before starting.
 */

// window.addEventListener('load',function(){
	// setTimeout(doIt,initialDelay);
// },false);

/* This method ensures a few small chunks of interaction time before we start. */
function startCountdown(total,fnToDo) {
	function doCountdown(msToGo) {
		if (msToGo > 0) {
			setTimeout(function(){
				doCountdown(msToGo-20);
			},20);
		} else {
			fnToDo();
		}
	}
	doCountdown(total);
}
startCountdown(initialDelay,doIt);

// Alternatively, just: setTimeout(doIt,initialDelay);