/* ephemera.js is part of Aloha Editor project http://aloha-editor.org
 *
 * Aloha Editor is a WYSIWYG HTML5 inline editing library and editor. 
 * Copyright (c) 2010-2012 Gentics Software GmbH, Vienna, Austria.
 * Contributors http://aloha-editor.org/contribution.php 
 * 
 * Aloha Editor 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
 * of the License, or any later version.
 *
 * Aloha Editor 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * 
 * As an additional permission to the GNU GPL version 2, you may distribute
 * non-source (e.g., minimized or compacted) forms of the Aloha-Editor
 * source code without the copy of the GNU GPL normally required,
 * provided you include this license notice and a URL through which
 * recipients can access the Corresponding Source.
 */
define([
	'jquery',
	'util/maps',
	'util/strings',
	'util/browser'
], function (
	$,
	Maps,
	Strings,
	Browser
) {
	'use strict';

	var spacesRx = /\s+/;
	var attrRegex = /\s([^\/<>\s=]+)(?:=(?:"[^"]*"|'[^']*'|[^>\/\s]+))?/g;

	/**
	 * Like insertBefore, inserts firstChild into parent before
	 * refChild, except also inserts all the following siblings of
	 * firstChild.
	 */
	function moveNextAll(parent, firstChild, refChild) {
		while (firstChild) {
			var nextChild = firstChild.nextSibling;
			parent.insertBefore(firstChild, refChild);
			firstChild = nextChild;
		}
	}

	/**
	 * Used to serialize outerHTML of DOM elements in older (pre-HTML5) Gecko,
	 * Safari, and Opera browsers.
	 *
	 * Beware that XMLSerializer generates an XHTML string (<div class="team" />
	 * instead of <div class="team"></div>).  It is noted here:
	 * http://stackoverflow.com/questions/1700870/how-do-i-do-outerhtml-in-firefox
	 * that some browsers (like older versions of Firefox) have problems with
	 * XMLSerializer, and an alternative, albeit more expensive option, is
	 * described.
	 *
	 * @type {XMLSerializer|null}
	 */
	var Serializer = window.XMLSerializer && new window.XMLSerializer();

	/**
	 * Gets the serialized HTML that describes the given DOM element and its
	 * innerHTML.
	 *
	 * Polyfill for older versions of Gecko, Safari, and Opera browsers.
	 * @see https://bugzilla.mozilla.org/show_bug.cgi?id=92264 for background.
	 *
	 * @param {HTMLElement} node DOM Element.
	 * @return {String}
	 */
	function outerHtml(node) {
		var html = node.outerHTML;
		if (typeof html !== 'undefined') {
			return html;
		}
		try {
			return Serializer ? Serializer.serializeToString(node) : node.xml;
		} catch (e) {
			return node.xml;
		}
	}

	/**
	 * Retrieves the names of all attributes from the given elmenet.
	 *
	 * Correctly handles the case that IE7 and IE8 have approx 70-90
	 * default attributes on each and every element.
	 *
	 * This implementation does not iterate over the elem.attributes
	 * property since that is much slower on IE7 (even when
	 * checking the attrNode.specified property). Instead it parses the
	 * HTML of the element. For elements with few attributes the
	 * performance on IE7 is improved by an order of magnitued.
	 *
	 * On IE7, when you clone a <button disabled="disabled"/> or an
	 * <input checked="checked"/> element the boolean properties will
	 * not be set on the cloned node. We choose the speed optimization
	 * over correctness in this case. The dom-to-xhtml plugin has a
	 * workaround for this case.
	 */
	function attrNames(elem) {
		var names = [];
		var html = outerHtml(elem.cloneNode(false));
		var match;
		while (null != (match = attrRegex.exec(html))) {
			names.push(match[1]);
		}
		return names;
	}

	/**
	 * Gets the attributes of the given element.
	 *
	 * See attrNames() for an edge case on IE7.
	 *
	 * @param elem
	 *        An element to get the attributes for.
	 * @return
	 *        An array containing [name, value] tuples for each attribute.
	 *        Attribute values will always be strings, but possibly empty strings.
	 */
	function attrs(elem) {
		var as = [];
		var names = attrNames(elem);
		var i;
		var len;
		for (i = 0, len = names.length; i < len; i++) {
			var name = names[i];
			var value = $.attr(elem, name);
			if (null == value) {
				value = "";
			} else {
				value = value.toString();
			}
			as.push([name, value]);
		}
		return as;
	}

	/**
	 * Like indexByClass() but operates on a list of elements instead.
	 * The given list may be a NodeList, HTMLCollection, or an array.
	 */
	function indexByClassHaveList(elems, classMap) {
		var index = {},
		    indexed,
		    classes,
		    elem,
		    cls,
		    len,
		    i,
		    j;
		for (i = 0, len = elems.length; i < len; i++) {
			elem = elems[i];
			if (elem.className) {
				classes = Strings.words(elem.className);
				for (j = 0; j < classes.length; j++) {
					cls = classes[j];
					if (classMap[cls]) {
						indexed = index[cls];
						if (indexed) {
							indexed.push(elem);
						} else {
							index[cls] = [elem];
						}
					}
				}
			}
		}
		return index;
	}

	/**
	 * Indexes descendant elements based on the individual classes in
	 * the class attribute.
	 *
	 * Based on these observations;
	 * 
	 * * $('.class1, .class2') takes twice as long as $('.class1') on IE7.
	 *
	 * * $('.class1, .class2') is fast on IE8 (approx the same as
	 *   $('.class'), no matter how many classes), but if the individual
	 *   elements in the result set should be handled differently, the
	 *   subsequent hasClass('.class1') and hasClass('.class2') calls
	 *   slow things down again.
	 *
	 * * DOM traversal with elem.firstChild elem.nextSibling is very
	 *   slow on IE7 compared to just iterating over
	 *   root.getElementsByTagName('*').
	 *
	 * * $('name.class') is much faster than just $('.class'), but as
	 *   soon as you need a single class in classMap that may be present
	 *   on any element, that optimization doesn't gain anything since
	 *   then you have to examine every element.
	 *
	 * This function will always take approx. the same amount of time
	 * (on IE7 approx. equivalent to a single call to $('.class')) no
	 * matter how many entries there are in classMap to index.
	 *
	 * This function only makes sense for multiple entries in
	 * classMap. For a single class lookup, $('.class') or
	 * $('name.class') is fine (even better in the latter case).
	 *
	 * @param root
	 *        The root element to search for elements to index
	 *        (will not be included in search).
	 * @param classMap
	 *        A map from class name to boolean true.
	 * @return
	 *        A map from class name to an array of elements with that class.
	 *        Every entry in classMap for which elements have been found
	 *        will have a corresponding entry in the returned
	 *        map. Entries for which no elements have been found, may or
	 *        may not have an entry in the returned map.
	 */
	function indexByClass(root, classMap) {
		var elems;
		if (Browser.ie7) {
			elems = root.getElementsByTagName('*');
		} else {
			// Optimize for browsers that support querySelectorAll/getElementsByClassName.
			// On IE8 for example, if there is a relatively high
			// elems/resultSet ratio, performance can improve by a factor of 2.
			elems = $(root).find('.' + Maps.keys(classMap).join(',.'));
		}
		return indexByClassHaveList(elems, classMap);
	}

	/**
	 * Indexes descendant elements based on elem.nodeName.
	 *
	 * Based on these observations:
	 *
	 * * On IE8, for moderate values of names.length, individual calls to
	 *   getElementsByTagName is just as fast as $root.find('name, name,
	 *   name, name').
	 *
	 * * On IE7, $root.find('name, name, name, name') is extemely slow
	 *   (can be an order of magnitude slower than individual calls to
	 *    getElementsByTagName, why is that?).
	 *
	 * * Although getElementsByTagName is very fast even on IE7, when
	 *   names.length > 7 an alternative implementation that iterates
	 *   over all tags and checks names from a hashmap (similar to how
	 *   indexByClass does it) may become interesting, but
	 *   names.length > 7 is unlikely.
	 *
	 * This function only makes sense if the given names array has many
	 * entries. For only one or two different names, calling $('name')
	 * or context.getElementsByTagName(name) directly is fine (but
	 * beware of $('name, name, ...') as explained above).
	 *
	 * The signature of this function differs from indexByClass by not
	 * taking a map but instead an array of names.
	 *
	 * @param root
	 *        The root element to search for elements to index
	 *        (will not be included in search).
	 * @param names
	 *        An array of element names to look for.
	 *        Names must be in all-uppercase (the same as elem.nodeName).
	 * @return
	 *        A map from element name to an array of elements with that name.
	 *        Names will be all-uppercase.
	 *        Arrays will be proper arrays, not NodeLists.
	 *        Every entry in classMap for which elements have been found
	 *        will have a corresponding entry in the returned
	 *        map. Entries for which no elements have been found, may or
	 *        may not have an entry in the returned map.
	 */
	function indexByName(root, names) {
		var i,
		    index = {},
		    len;
		for (i = 0, len = names.length; i < len; i++) {
			var name = names[i];
			index[name] = $.makeArray(root.getElementsByTagName(name));
		}
		return index;
	}

	return {
		moveNextAll: moveNextAll,
		attrNames: attrNames,
		attrs: attrs,
		indexByClass: indexByClass,
		indexByName: indexByName,
		indexByClassHaveList: indexByClassHaveList,
		outerHtml: outerHtml
	};
});