/*
Script: Ajax.js
        Contains the <Ajax> class. Also contains methods to generate querystings from forms and Objects.

Credits:
        Loosely based on the version from prototype.js <http://prototype.conio.net>

License:
        MIT-style license.
*/

/*
Class: Ajax
        An Ajax class, For all your asynchronous needs.
        Inherits methods, properties, options and events from <XHR>.

Arguments:
        url - the url pointing to the server-side script.
        options - optional, an object containing options.

Options:
        data - you can write parameters here. Can be a querystring, an object or a Form element.
        update - $(element) to insert the response text of the XHR into, upon completion of the request.
        evalScripts - boolean; default is false. Execute scripts in the response text onComplete. When the response is javascript the whole response is evaluated.
        evalResponse - boolean; default is false. Force global evalulation of the whole response, no matter what content-type it is.

Events:
        onComplete - function to execute when the ajax request completes.

Example:
        >var myAjax = new Ajax(url, {method: 'get'}).request();
*/

var Ajax = XHR.extend({

        options: {
                data: null,
                update: null,
                onComplete: Class.empty,
                evalScripts: false,
                evalResponse: false
        },

        initialize: function(url, options){
                this.addEvent('onSuccess', this.onComplete);
                this.setOptions(options);
                /*compatibility*/
                this.options.data = this.options.data || this.options.postBody;
                /*end compatibility*/
                if (!['post', 'get'].contains(this.options.method)){
                        this._method = '_method=' + this.options.method;
                        this.options.method = 'post';
                }
                this.parent();
                this.setHeader('X-Requested-With', 'XMLHttpRequest');
                this.setHeader('Accept', 'text/javascript, text/html, application/xml, text/xml, */*');
                this.url = url;
        },

        onComplete: function(){
                if (this.options.update) $(this.options.update).empty().setHTML(this.response.text);
                if (this.options.evalScripts || this.options.evalResponse) this.evalScripts();
                this.fireEvent('onComplete', [this.response.text, this.response.xml], 20);
        },

        /*
        Property: request
                Executes the ajax request.

        Example:
                >var myAjax = new Ajax(url, {method: 'get'});
                >myAjax.request();

                OR

                >new Ajax(url, {method: 'get'}).request();
        */

        request: function(data){
                data = data || this.options.data;
                switch($type(data)){
                        case 'element': data = $(data).toQueryString(); break;
                        case 'object': data = Object.toQueryString(data);
                }
                if (this._method) data = (data) ? [this._method, data].join('&') : this._method;
                return this.send(this.url, data);
        },

        /*
        Property: evalScripts
                Executes scripts in the response text
        */

        evalScripts: function(){
                var script, scripts;
                if (this.options.evalResponse || (/(ecma|java)script/).test(this.getHeader('Content-type'))) scripts = this.response.text;
                else {
                        scripts = [];
                        var regexp = /<script[^>]*>([\s\S]*?)<\/script>/gi;
                        while ((script = regexp.exec(this.response.text))) scripts.push(script[1]);
                        scripts = scripts.join('\n');
                }
                if (scripts) (window.execScript) ? window.execScript(scripts) : window.setTimeout(scripts, 0);
        },

        /*
        Property: getHeader
                Returns the given response header or null
        */

        getHeader: function(name){
                try {return this.transport.getResponseHeader(name);} catch(e){};
                return null;
        }

});

/* Section: Object related Functions */

/*
Function: Object.toQueryString
        Generates a querystring from key/pair values in an object

Arguments:
        source - the object to generate the querystring from.

Returns:
        the query string.

Example:
        >Object.toQueryString({apple: "red", lemon: "yellow"}); //returns "apple=red&lemon=yellow"
*/

Object.toQueryString = function(source){
        var queryString = [];
        for (var property in source) queryString.push(encodeURIComponent(property) + '=' + encodeURIComponent(source[property]));
        return queryString.join('&');
};

/*
Class: Element
        Custom class to allow all of its methods to be used with any DOM element via the dollar function <$>.
*/

Element.extend({

        /*
        Property: send
                Sends a form with an ajax post request

        Arguments:
                options - option collection for ajax request. See <Ajax> for the options list.

        Returns:
                The Ajax Class Instance

        Example:
                (start code)
                <form id="myForm" action="submit.php">
                <input name="email" value="bob@bob.com">
                <input name="zipCode" value="90210">
                </form>
                <script>
                $('myForm').send()
                </script>
                (end)
        */

        send: function(options){
                return new Ajax(this.getProperty('action'), $merge({data: this.toQueryString()}, options, {method: 'post'})).request();
        }


});