// Google Cache Continue Redux
// Based on Google Cache Continue by Jonathon Ramsey
// v0.3

// Copyright (C) 2005-2008 by
//   Jonathon Ramsey (jonathon.ramsey@gmail.com)
//   Jeffery To (jeffery.to @gmail.com)

// This file 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 2, or (at your
// option) any later version.

// This file 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 software; see the file COPYING. If not, write to
// the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.

// (Comment by Jonathon Ramsey:)
// Thanks to Neil Klopfenstein for a fix to deal with the text only
// version of cached pages

// ==UserScript==
// @name           Google Cache Continue Redux
// @namespace      http://www.thingsthemselves.com/greasemonkey/
// @description    Add links to Google cache results to allow continuing using the cache, keeping search terms highlighted
// @include        http://*/search?*q=cache:*
// @include        http://*/search?*q=cache%3A*
// @include        http://*/search?*q=cache%3a*
// ==/UserScript==

// Redux changelog:

// v0.3 (2008-11-27)
// - Fixed duplicate "http://" in uncached link when search URL includes the protocol

// v0.2 (2008-08-19)
// - Externalized strings in about:config prefs

// v0.1 (2008-07-31)
// - Initial version

(function() {
	/* Customize these in about:config if you use Google in a language other than English */
	var defaults = {
		// If the page title ends with this text, then Google does not have a cached version of the page
		// about:config name: greasemonkey.scriptvals.http://www.thingsthemselves.com/greasemonkey//Google Cache Continue Redux.noCacheTitle
		noCacheTitle: 'Google Search',

		// Link text for Google's text-only version link
		// about:config name: greasemonkey.scriptvals.http://www.thingsthemselves.com/greasemonkey//Google Cache Continue Redux.textOnlyLinkText
		textOnlyLinkText: 'Text-only version',

		// Link text for Google's full version link
		// about:config name: greasemonkey.scriptvals.http://www.thingsthemselves.com/greasemonkey//Google Cache Continue Redux.fullLinkText
		fullLinkText: 'Full version',

		// Link text for cache links
		// about:config name: greasemonkey.scriptvals.http://www.thingsthemselves.com/greasemonkey//Google Cache Continue Redux.cacheLinkText
		cacheLinkText: 'cache',

		// Explanation text for uncached link, for when Google does not have a cached version of the page
		// %s will be replaced by the uncached link
		// about:config name: greasemonkey.scriptvals.http://www.thingsthemselves.com/greasemonkey//Google Cache Continue Redux.uncachedText
		uncachedText: '<b>Uncached:</b> %s',

		// Explanation text for cached page
		// %s will be replaced by the sample cache link
		// about:config name: greasemonkey.scriptvals.http://www.thingsthemselves.com/greasemonkey//Google Cache Continue Redux.explanationText
		explanationText: 'Use %s links to continue using the Google cache.'
	};

	/* Modify these to change the appearance of the cache links */
	var cacheLinkStyle = '\
		a.googleCache {\
			position: static !important;\
			display: inline !important;\
			visibility: visible !important;\
			margin: 0.3ex !important;\
			padding: 0 0.6ex 0.4ex 0.3ex !important;\
			border: none !important;\
			font: normal bold x-small sans-serif !important;\
			background: yellow !important;\
			color: red !important;\
			text-align: left !important;\
			text-decoration: none !important;\
			text-transform: none !important;\
			letter-spacing: normal !important;\
			word-spacing: normal !important;\
			vertical-align: baseline !important;\
			cursor: auto !important;\
		}\
		a.googleCache:hover {\
			color: yellow !important;\
			background-color: red !important;\
		}\
		p#googleCacheExplanation {\
			position: static !important;\
			display: block !important;\
			visibility: visible !important;\
			width: auto !important;\
			height: auto !important;\
			margin: 1em 0;\
			padding: 1ex 0.5ex;\
			border: 1px solid #3366CC;\
			font-family: inherit !important;\
			font-style: normal !important;\
			font-variant: normal !important;\
			font-weight: normal !important;\
			font-stretch: normal !important;\
			font-size: inherit !important;\
			font-size-adjust: none !important;\
			line-height: inherit !important;\
			background: transparent !important;\
			color: black !important;\
			text-align: left !important;\
			text-decoration: none !important;\
			text-transform: none !important;\
			letter-spacing: normal !important;\
			word-spacing: normal !important;\
			vertical-align: baseline !important;\
			cursor: auto !important;\
		}\
	';

	var settings = {};
	var cacheTerm = null;
	var url = null;
	var q = null;
	var links, alter, link;
	var parts, len, p, i;

	// look for the user's url and the cache term ("cache:url")

	parts = document.location.search.substring(1).split('&');
	len = parts.length;
	for (i = 0; i < parts.length; i++) {
		p = parts[i].split('=');
		if (p[0] == 'q') {
			q = p[1];
			break;
		}
	}

	if (q == null) {
		return;
	}

	parts = q.split('+');
	len = parts.length;
	for (i = 0; i < len; i++) {
		p = decodeURIComponent(parts[i]);
		if (p.indexOf('cache:') == 0) {
			cacheTerm = parts[i];
			url = p.substring(6);
			break;
		}
	}

	if (cacheTerm == null) {
		return;
	}

	// load settings
	if (typeof GM_getValue != 'undefined' && typeof GM_setValue != 'undefined') {
		for (i in defaults) {
			p = GM_getValue(i);
			if (typeof p == 'undefined') {
				p = defaults[i];
				GM_setValue(i, p);
			}
			settings[i] = p;
		}
	} else {
		// can't load settings, so use defaults
		settings = defaults;
	}

	addStyles(cacheLinkStyle);

	if (googleHasNoCache()) {
		return addUncachedLink();
	}

	/* get a snapshot from the live dom */
	links = document.evaluate("//a[@href]",
	                          document,
	                          null,
	                          XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
	                          null);
	alter = false;
	link = null;
	for (i = 0; (link = links.snapshotItem(i)); i++) {
		if (alter) {
			if (linkIsHttp(link)) {
				addCacheLink(link);
			}
		} else {
			if (isLastGoogleLink(link)) {
				alter = true;
				addExplanation(link);
			}
		}
	}

	function addStyles(rules) {
		var style = document.createElement('style');
		style.type = 'text/css';
		style.innerHTML = rules;
		document.body.appendChild(style);
	}

	function googleHasNoCache() {
		var title = document.title;
		return (title.indexOf('cache:' + url) > -1 &&
			title.search(new RegExp(' - ' + settings.noCacheTitle + '$')) >
			-1);
	}

	function addUncachedLink() {
		var p = document.createElement('p');
		p.id = 'googleCacheExplanation';
		p.innerHTML = settings.uncachedText.replace(/%s/g, '<a href="' + ((url.search(/:\/\//) == -1) ? 'http://' : '') + url + '">' + url + '</a>');
		var suggestion_header =
			document.getElementsByTagName('ul')[0].previousSibling.previousSibling;
		suggestion_header.parentNode.replaceChild(p, suggestion_header);
	}

	function linkIsHttp(link) {
		return (link.protocol == 'http:');
	}

	function isLastGoogleLink(link) {
		return (link.text == settings.textOnlyLinkText ||
			link.text == settings.fullLinkText);
	}

	function addExplanation(link) {
		var p = document.createElement('p');
		p.id = 'googleCacheExplanation';
		p.innerHTML = settings.explanationText.replace(/%s/g,
			'<a href="' + document.location.href + '" class="googleCache">' + settings.cacheLinkText + '</a>');
		link.parentNode.parentNode.appendChild(p);
	}

	function addCacheLink(link) {
		var a = document.createElement('a');
		a.href = getCacheLinkHref(link);
		a.appendChild(document.createTextNode(settings.cacheLinkText));
		a.className = 'googleCache';
		link.parentNode.insertBefore(a, link.nextSibling);
	}

	function getCacheLinkHref(link) {
		var curHref = document.location.href;
		var curHash = document.location.hash;
		var href = link.href.replace(/^http:\/\//, '');
		var hash = link.hash;
		var fragment = '';
		if (curHash) {
			curHref = curHref.replace(curHash, '');
		}
		if (hash) {
			href = href.replace(hash, '');
			fragment = hash;
		}
		return curHref.replace(cacheTerm,
			encodeURIComponent('cache:' + href)) + fragment;
	}

})();