/**
 * @class Ext.DomHelper
 * 
The DomHelper class provides a layer of abstraction from DOM and transparently supports creating
 * elements via DOM or using HTML fragments. It also has the ability to create HTML fragment templates
 * from your DOM building code.

 *
 * 
DomHelper element specification object

 * 
A specification object is used when creating elements. Attributes of this object
 * are assumed to be element attributes, except for 4 special attributes:
 * 

 *
 * 
Insertion methods

 * 
Commonly used insertion methods:
 * 

 *
 * 
Example

 * 
This is an example, where an unordered list with 3 children items is appended to an existing
 * element with id 'my-div':

 

var dh = Ext.DomHelper; // create shorthand alias
// specification object
var spec = {
    id: 'my-ul',
    tag: 'ul',
    cls: 'my-list',
    // append children after creating
    children: [     // may also specify 'cn' instead of 'children'
        {tag: 'li', id: 'item0', html: 'List Item 0'},
        {tag: 'li', id: 'item1', html: 'List Item 1'},
        {tag: 'li', id: 'item2', html: 'List Item 2'}
    ]
};
var list = dh.append(
    'my-div', // the context element 'my-div' can either be the id or the actual node
    spec      // the specification object
);
 

 * 
Element creation specification parameters in this class may also be passed as an Array of
 * specification objects. This can be used to insert multiple sibling nodes into an existing
 * container very efficiently. For example, to add more list items to the example above:

dh.append('my-ul', [
    {tag: 'li', id: 'item3', html: 'List Item 3'},
    {tag: 'li', id: 'item4', html: 'List Item 4'}
]);
 * 

 *
 * 
Templating

 * 
The real power is in the built-in templating. Instead of creating or appending any elements,
 * {@link #createTemplate} returns a Template object which can be used over and over to
 * insert new elements. Revisiting the example above, we could utilize templating this time:
 * 

// create the node
var list = dh.append('my-div', {tag: 'ul', cls: 'my-list'});
// get template
var tpl = dh.createTemplate({tag: 'li', id: 'item{0}', html: 'List Item {0}'});

for(var i = 0; i < 5, i++){
    tpl.append(list, [i]); // use template to append to the actual node
}
 * 

 * 
An example using a template:

var html = '{2}';

var tpl = new Ext.DomHelper.createTemplate(html);
tpl.append('blog-roll', ['link1', 'http://www.jackslocum.com/', "Jack's Site"]);
tpl.append('blog-roll', ['link2', 'http://www.dustindiaz.com/', "Dustin's Site"]);
 * 

 *
 * 
The same example using named parameters:

var html = '{text}';

var tpl = new Ext.DomHelper.createTemplate(html);
tpl.append('blog-roll', {
    id: 'link1',
    url: 'http://www.jackslocum.com/',
    text: "Jack's Site"
});
tpl.append('blog-roll', {
    id: 'link2',
    url: 'http://www.dustindiaz.com/',
    text: "Dustin's Site"
});
 * 

 *
 * 
Compiling Templates

 * 
Templates are applied using regular expressions. The performance is great, but if
 * you are adding a bunch of DOM elements using the same template, you can increase
 * performance even further by {@link Ext.Template#compile "compiling"} the template.
 * The way "{@link Ext.Template#compile compile()}" works is the template is parsed and
 * broken up at the different variable points and a dynamic function is created and eval'ed.
 * The generated function performs string concatenation of these parts and the passed
 * variables instead of using regular expressions.
 * 

var html = '{text}';

var tpl = new Ext.DomHelper.createTemplate(html);
tpl.compile();

//... use template like normal
 * 

 *
 * 
Performance Boost

 * 
DomHelper will transparently create HTML fragments when it can. Using HTML fragments instead
 * of DOM can significantly boost performance.

 * 
Element creation specification parameters may also be strings. If {@link #useDom} is false,
 * then the string is used as innerHTML. If {@link #useDom} is true, a string specification
 * results in the creation of a text node. Usage:

 * 

Ext.DomHelper.useDom = true; // force it to use DOM; reduces performance
 * 

 * @singleton
 */
Ext.DomHelper = function(){
    var tempTableEl = null,
        emptyTags = /^(?:br|frame|hr|img|input|link|meta|range|spacer|wbr|area|param|col)$/i,
        tableRe = /^table|tbody|tr|td$/i,
        pub,
        // kill repeat to save bytes
        afterbegin = "afterbegin",
        afterend = "afterend",
        beforebegin = "beforebegin",
        beforeend = "beforeend",
        ts = '',
        te = '
',
        tbs = ts+'',
        tbe = ''+te,
        trs = tbs + '',
        tre = ''+tbe;

    // private
    function doInsert(el, o, returnElement, pos, sibling, append){
        var newNode = pub.insertHtml(pos, Ext.getDom(el), createHtml(o));
        return returnElement ? Ext.get(newNode, true) : newNode;
    }

    // build as innerHTML where available
    function createHtml(o){
            var b = "",
                attr,
                val,
                key,
                keyVal,
                cn;

        if(typeof o == 'string'){
            b = o;
        } else if (Ext.isArray(o)) {
                Ext.each(o, function(v) {
                b += createHtml(v);
            });
        } else {
                b += "<" + (o.tag = o.tag || "div");
            Ext.iterate(o, function(attr, val){
                if(!/tag|children|cn|html$/i.test(attr)){
                    if (Ext.isObject(val)) {
                        b += " " + attr + "='";
                        Ext.iterate(val, function(key, keyVal){
                            b += key + ":" + keyVal + ";";
                        });
                        b += "'";
                    }else{
                        b += " " + ({cls : "class", htmlFor : "for"}[attr] || attr) + "='" + val + "'";
                    }
                }
            });
                // Now either just close the tag or try to add children and close the tag.
                if (emptyTags.test(o.tag)) {
                    b += "/>";
                } else {
                    b += ">";
                    if ((cn = o.children || o.cn)) {
                        b += createHtml(cn);
                    } else if(o.html){
                        b += o.html;
                    }
                    b += "";
                }
        }
        return b;
    }

    function ieTable(depth, s, h, e){
        tempTableEl.innerHTML = [s, h, e].join('');
        var i = -1,
                el = tempTableEl;
        while(++i < depth){
            el = el.firstChild;
        }
        return el;
    }

    /**
     * @ignore
     * Nasty code for IE's broken table implementation
     */
    function insertIntoTable(tag, where, el, html) {
            var node,
                before;

        tempTableEl = tempTableEl || document.createElement('div');

            if(tag == 'td' && (where == afterbegin || where == beforeend) ||
               !/td|tr|tbody/i.test(tag) && (where == beforebegin || where == afterend)) {
            return;
        }
        before = where == beforebegin ? el :
                                 where == afterend ? el.nextSibling :
                                 where == afterbegin ? el.firstChild : null;

        if (where == beforebegin || where == afterend) {
                el = el.parentNode;
        }

        if (tag == 'td' || (tag == "tr" && (where == beforeend || where == afterbegin))) {
                node = ieTable(4, trs, html, tre);
        } else if ((tag == "tbody" && (where == beforeend || where == afterbegin)) ||
                           (tag == "tr" && (where == beforebegin || where == afterend))) {
                node = ieTable(3, tbs, html, tbe);
        } else {
                node = ieTable(2, ts, html, te);
        }
        el.insertBefore(node, before);
        return node;
    }


    pub = {
            
/**
             * Returns the markup for the passed Element(s) config.
             * @param {Object} o The DOM object spec (and children)
             * @return {String}
             */
            markup : function(o){
                return createHtml(o);
            },

            
/**
             * Inserts an HTML fragment into the DOM.
             * @param {String} where Where to insert the html in relation to el - beforeBegin, afterBegin, beforeEnd, afterEnd.
             * @param {HTMLElement} el The context element
             * @param {String} html The HTML fragmenet
             * @return {HTMLElement} The new node
             */
            insertHtml : function(where, el, html){
                var hash = {},
                        hashVal,
                        setStart,
                        range,
                        frag,
                        rangeEl,
                        rs;

                where = where.toLowerCase();
                // add these here because they are used in both branches of the condition.
                hash[beforebegin] = ['BeforeBegin', 'previousSibling'];
                hash[afterend] = ['AfterEnd', 'nextSibling'];

                if (el.insertAdjacentHTML) {
                    if(tableRe.test(el.tagName) && (rs = insertIntoTable(el.tagName.toLowerCase(), where, el, html))){
                        return rs;
                    }
                    // add these two to the hash.
                    hash[afterbegin] = ['AfterBegin', 'firstChild'];
                    hash[beforeend] = ['BeforeEnd', 'lastChild'];
                    if ((hashVal = hash[where])) {
                                el.insertAdjacentHTML(hashVal[0], html);
                        return el[hashVal[1]];
                    }
                } else {
                        range = el.ownerDocument.createRange();
                        setStart = "setStart" + (/end/i.test(where) ? "After" : "Before");
                        if (hash[where]) {
                                range[setStart](el);
                                frag = range.createContextualFragment(html);
                                el.parentNode.insertBefore(frag, where == beforebegin ? el : el.nextSibling);
                                return el[(where == beforebegin ? "previous" : "next") + "Sibling"];
                        } else {
                                rangeEl = (where == afterbegin ? "first" : "last") + "Child";
                                if (el.firstChild) {
                                        range[setStart](el[rangeEl]);
                                        frag = range.createContextualFragment(html);
                        if(where == afterbegin){
                            el.insertBefore(frag, el.firstChild);
                        }else{
                            el.appendChild(frag);
                        }
                                } else {
                                    el.innerHTML = html;
                            }
                            return el[rangeEl];
                        }
                }
                throw 'Illegal insertion point -> "' + where + '"';
            },

            
/**
             * Creates new DOM element(s) and inserts them before el.
             * @param {Mixed} el The context element
             * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
             * @param {Boolean} returnElement (optional) true to return a Ext.Element
             * @return {HTMLElement/Ext.Element} The new node
             */
            insertBefore : function(el, o, returnElement){
                return doInsert(el, o, returnElement, beforebegin);
            },

            
/**
             * Creates new DOM element(s) and inserts them after el.
             * @param {Mixed} el The context element
             * @param {Object} o The DOM object spec (and children)
             * @param {Boolean} returnElement (optional) true to return a Ext.Element
             * @return {HTMLElement/Ext.Element} The new node
             */
            insertAfter : function(el, o, returnElement){
                return doInsert(el, o, returnElement, afterend, "nextSibling");
            },

            
/**
             * Creates new DOM element(s) and inserts them as the first child of el.
             * @param {Mixed} el The context element
             * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
             * @param {Boolean} returnElement (optional) true to return a Ext.Element
             * @return {HTMLElement/Ext.Element} The new node
             */
            insertFirst : function(el, o, returnElement){
                return doInsert(el, o, returnElement, afterbegin, "firstChild");
            },

            
/**
             * Creates new DOM element(s) and appends them to el.
             * @param {Mixed} el The context element
             * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
             * @param {Boolean} returnElement (optional) true to return a Ext.Element
             * @return {HTMLElement/Ext.Element} The new node
             */
            append : function(el, o, returnElement){
                    return doInsert(el, o, returnElement, beforeend, "", true);
            },

            
/**
             * Creates new DOM element(s) and overwrites the contents of el with them.
             * @param {Mixed} el The context element
             * @param {Object/String} o The DOM object spec (and children) or raw HTML blob
             * @param {Boolean} returnElement (optional) true to return a Ext.Element
             * @return {HTMLElement/Ext.Element} The new node
             */
            overwrite : function(el, o, returnElement){
                el = Ext.getDom(el);
                el.innerHTML = createHtml(o);
                return returnElement ? Ext.get(el.firstChild) : el.firstChild;
            },

            createHtml : createHtml
    };
    return pub;
}();