(function(cfg){
    var defaults = {
        context: window,
        name: 'jsxml',
        file_cache: true,
        errors: 'alert' // throw, ignore
    };
    if (!cfg) cfg = {};
    for (var i in defaults)
        if (cfg[i]) defaults[i] = cfg[i];
    cfg = defaults;
    
    // conveyor is used to build and execute callback chains
    var conveyor = function(cb){
        if (cb) this.cb = cb;
        this.tasks = [];
    };
    conveyor.prototype.add = function(task){
        this.tasks.push(task);
    };
    conveyor.prototype.exe = function(i){
        if (typeof(i) == 'function') {
            this.cb = i;
            i = 0;
        };
        i = i ? i : 0;
        var $this = this;
        if (this.tasks.length > i) this.tasks[i](function(){
            $this.exe(i+1);
        }); else if (typeof(this.cb) == 'function') this.cb();
    };
    
    var lib = function(){},
        pro = {
            ajax: function(cfg){
                if (this._ajax === null) {
                    if (window.jQuery) {
                        this._ajax = jQuery.ajax;
                    } else if (window.Ext && window.Ext.Ajax) { // ExtJS
                        this._ajax = function(cfg){
                            Ext.Ajax.request({
                                url: cfg.url,
                                success: function(x){
                                    cfg.success(x.responseXML);
                                },
                                failure: cfg.error
                            });
                        };
                    } else if (window.Ajax && Ajax.Request) { // Prototype
                        this._ajax = function(cfg){
                            new Ajax.Request(cfg.url, {
                                method:'get',
                                onSuccess: function(x){
                                    cfg.success(x.responseXML);
                                },
                                onFailure: cfg.error,
                                onException: function(r, e) {
                                    cfg.error(e);
                                }
                            });
                        };
                    } else if (window.YAHOO) { // YAHOO
                        this._ajax = function(cfg){
                            YAHOO.util.Connect.asyncRequest('GET', cfg.url, {
                                success: function(x){
                                    cfg.success(x.responseXML);
                                },
                                failure: cfg.error
                            });
                        };
                    } else {
                        this._ajax = false;
                    };
                };
                if (this._ajax) {
                    try {
                        this._ajax(cfg);
                    } catch (e) {
                        cfg.error(e);
                    };
                } else this._throw(this._msgs.noajax);
            },
            
            /* The following two pieces of code are taken from http://www.alistapart.com/articles/crossbrowserscripting */
            nodeTypes: {
                ELEMENT_NODE: 1,
                ATTRIBUTE_NODE: 2,
                TEXT_NODE: 3,
                CDATA_SECTION_NODE: 4,
                ENTITY_REFERENCE_NODE: 5,
                ENTITY_NODE: 6,
                PROCESSING_INSTRUCTION_NODE: 7,
                COMMENT_NODE: 8,
                DOCUMENT_NODE: 9,
                DOCUMENT_TYPE_NODE: 10,
                DOCUMENT_FRAGMENT_NODE: 11,
                NOTATION_NODE: 12
            },
            
            importNode: function(document, node, allChildren) {
                /* find the node type to import */
                switch (node.nodeType) {
                    case this.nodeTypes.ELEMENT_NODE:
                        /* create a new element */
                        var newNode = document.createElement(node.nodeName);
                        /* does the node have any attributes to add? */
                        if (node.attributes && node.attributes.length > 0)
                            /* add all of the attributes */
                            for (var i = 0, il = node.attributes.length; i < il;)
                                newNode.setAttribute(node.attributes[i].nodeName, node.getAttribute(node.attributes[i++].nodeName));
                        /* are we going after children too, and does the node have any? */
                        if (allChildren && node.childNodes && node.childNodes.length > 0)
                            /* recursively get all of the child nodes */
                            for (var i = 0, il = node.childNodes.length; i < il;)
                                newNode.appendChild(this.importNode(document, node.childNodes[i++], allChildren));
                        return newNode;
                        break;
                    case this.nodeTypes.TEXT_NODE:
                    case this.nodeTypes.CDATA_SECTION_NODE:
                    case this.nodeTypes.COMMENT_NODE:
                        return document.createTextNode(node.nodeValue);
                        break;
                }
            },
            
            getMsDom: function () {
                // create IE xml DOM without ActiveX, submitted by alfalabs.net@gmail.com
                var xml = document.createElement('xml');
                xml.src = '<?xml version="1.0" encoding="UTF-8"?>';
                document.body.appendChild(xml);
                var xmlDocument = xml.XMLDocument;
                document.body.removeChild(xml);
                return xmlDocument;
            },
            
            newDoc: function(node){
                var d = window.ActiveXObject ? this.getMsDom() : document.implementation.createDocument("", node && !node.tagName ? node : 'test', null);
                if (window.ActiveXObject) {
                    if (node) {
                        if (node.tagName) {
                            d.appendChild(this.importNode(d, node, true));
                        } else {
                            d.appendChild(d.createElement(node));
                        };
                    };
                } else {
                    if (node.tagName) {
                        d.replaceChild(d.importNode(node, true), d.documentElement);
                    }
                };
                return d;
            },
            
            copy: function(obj){
                return this.fromString(this.toXml(obj));
            },
            
            fromStringOrObject: function(src) {
                return this.fromString(src) || this._fromObject(src);
            },
            
            fromString: function(str, checkXmlDeclaration) {
                if (typeof(str) != 'string') return false;
                checkXmlDeclaration = checkXmlDeclaration == undefined ? true : checkXmlDeclaration;
                if (checkXmlDeclaration && !/^<\?xml/.test(str)) return false;
                if (window.ActiveXObject) {
                    var o = this.newDoc();
                    o.loadXML(str);
                    if (!o.documentElement) {
                        this._throw(this._msgs.broken);
                        return false;
                    };
                    return o;
                } else {
                    var parser = new DOMParser(),
                        o = parser.parseFromString(str, 'text/xml'),
                        e = o.getElementsByTagName('parsererror');
                    if (e.length > 0) {
                        this._throw(this._msgs.broken);
                        return false;
                    } else return o;
                };
            },
            
            fromFile: function(file, callback, scope) {
                var cl = this._cache_loading,
                    c = this._cache,
                    $this = this;
                if (cl[file]) { // i.e. the same file is currently loading
                    if (cl[file] === true) cl[file] = new conveyor;
                    cl[file].add(function(cb){
                        callback.call(scope ? scope : c[file], c[file]);
                        cb();
                    });
                } else if (c[file]) {
                    callback.call(scope ? scope : c[file], c[file]);
                } else {
                    cl[file] = true;
                    this.ajax({
                        url: file,
                        success: function(xml){
                            if (!xml.documentElement) {
                                $this._throw($this._msgs.brokenfile + ': ' + file);
                                return;
                            };
                            c[file] = xml;
                            callback.call(scope ? scope : xml, xml);
                            if (typeof(cl[file]) == 'object') cl[file].exe();
                            if (cl[file]) delete cl[file];
                        },
                        error: function(e){
                            cl[file] = false;
                            if (e) {
                                var m = [];
                                m.push($this._msgs.exception + ":\r\n" + file);
                                if (e.name) m.push(e.name);
                                if (e.message) m.push(e.message);
                                $this._throw(m.join("\r\n"));
                            } else $this._throw($this._msgs.brokenfile + ': ' + file);
                        }
                    });
                };
            },

            load: function(source, callback, scope) {
                var o = this.fromStringOrObject(source);
                if (o) callback.call(scope ? scope : o, o);
                else this.fromFile(source, callback, scope);
            },
            
            toXml: function(source, xmlHeaderNeeded){
                xmlHeaderNeeded = xmlHeaderNeeded == false ? false : true;
                var xml = typeof(source) == 'string' ? source : (source.xml ? source.xml : new XMLSerializer().serializeToString(source)),
                    xmlHeaderPresent = /^<\?xml/.test(xml);
                if (xmlHeaderNeeded && /\="UTF\-16"\?/.test(xml)) xml = xml.replace(/\=\"UTF\-16\"\?/, '="UTF-8"?');
                if (xmlHeaderNeeded && !xmlHeaderPresent) return this._xmlHeader + xml;
                if (!xmlHeaderNeeded && xmlHeaderPresent) return xml.replace(/^<\?xml[^<]+/, '');
                return xml;
            },
            
            _borrowRootName: function(names){
                return names ? ( this._isA(names) ? names.shift() : names ) : 'root';
            },
            
            toDom: function(o, names, parentNode){
                rootName = this._borrowRootName(names);
                if (parentNode) parentNode = parentNode.appendChild(parentNode.ownerDocument.createElement(rootName));
                else parentNode = this.newDoc(rootName).documentElement;
                var t;
                if (this._isA(o)) {
                    for (var i = 0; i < o.length; i++ )
                        this.toDom(o[i], this._copy(names), parentNode);
                } else {
                    for (var i in o) {
                        t = typeof o[i];
                        switch (t) {
                            case 'string':
                            case 'number':
                            case 'boolean':
                                try {
                                    var v = t == 'boolean' ? (o[i]?1:0) : o[i];
                                    parentNode.setAttribute(i, String(v));
                                } catch(e) {
                                    this._throw('Unable to set attribute named "'+i+'"; ' + e.message);
                                };
                            break;
                            case 'object':
                                if (o[i] !== null)
                                    this.toDom(o[i], this._isA(names) ? [i].concat(names) : i, parentNode);
                            break;
                            default:
                                this._throw('Unsuitable type of index "' + i + '" for converting to XML: ' + t);
                                return false;
                            break;
                        };
                    };
                };
                return parentNode.ownerDocument.documentElement == parentNode ? parentNode.ownerDocument : parentNode;
            },
            
            trans: function(xmlSrc, xslSrc, callback, nativeResult, doc){
                var $this = this;
                this.load(xmlSrc, function(xml){
                    $this._trans2(xml, xslSrc, callback, nativeResult, doc);
                });
            },
            
            transReady: function(xmlSrc, xslSrc, nativeResult, doc){
                var xmlSrc = this.fromStringOrObject(xmlSrc),
                    xslSrc = this.fromStringOrObject(xslSrc),
                    r;
                if (!xmlSrc || !xslSrc) return false;
                try {
                    if (window.ActiveXObject) {
                        r = xmlSrc.transformNode(xslSrc);
                        r = this.fromStringOrObject(r) || r;
                    } else {
                        var processor = new XSLTProcessor();
                        processor.importStylesheet(xslSrc);
                        r = doc ? processor.transformToDocument(xmlSrc) : processor.transformToFragment(xmlSrc, document);
                    };
                } catch (e) {
                    this._throw(this._msgs.brokenxslt);
                    return false;
                };
                return nativeResult ? r : this.toXml(r, false);
            },
            
            getXslWrap: function(cfg){
                cfg = cfg || {};
                cfg.indent = cfg.indent ? cfg.indent : 'yes';
                cfg.method = cfg.method ? cfg.method : 'html';
                return ['<?xml version="1.0" encoding="UTF-8"?><xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"><xsl:output encoding="UTF-8" indent="' + cfg.indent + '" method="' + cfg.method + '" />', '</xsl:stylesheet>'];
            },
            
            _trans2: function(xml, xslSrc, callback, nativeResult, doc){
                this.load(xslSrc, function(xsl){
                    var scope;
                    if (callback && typeof callback.length == "number" && typeof callback.splice == "function") {
                        scope = callback[1];
                        callback = callback[0];
                    } else scope = callback;
                    callback.call(scope, this.transReady(xml, xsl, nativeResult, doc));
                }, this);
            },
            
            _throw: function(msg){
                var sourceAppName = 'JSXML';
                switch (cfg.errors) {
                    case 'alert':
                        alert(sourceAppName + ":\r\n" + msg);
                    break;
                    case 'throw':
                        throw sourceAppName + ":\r\n" + msg;
                    break;
                };
            },
            _ajax: null,
            _fromObject: function(el) {
                if (!el.documentElement) {
                    if (el.tagName)  {
                        return this.newDoc(el);
                    }
                    return false;
                };
                return el;
            },
            _xmlHeader: '<?xml version="1.0" encoding="UTF-8"?>\r\n',
            _cache: {},
            _isA: function(v){
                return v && typeof v.length == "number" && typeof v.splice == "function";
            },
            _copy: function(o){
                if (typeof o != 'object' || o === null) return o;
                var r;
                if (this._isA(o)) {
                    r = [];
                    for (var i = 0; i < o.length; i++) r.push(o[i]);
                } else {
                    r = {};
                    for (var i in o) r[i] = o[i]
                };
                return r;
            },
            _cache_loading: {},
            _msgs: {
                broken: 'Broken XML string',
                brokenfile: 'Broken XML file',
                brokenxslt: 'Broken XSLT',
                noajax: 'No AJAX library found. See docs for supported libraries.',
                exception: 'An exception happened while trying to load url'
            }
        };
    for (var i in pro) lib.prototype[i] = pro[i];
    cfg.context[cfg.name] = new lib;
})();