/**
 * A method for submitting an HTML form using AJAX, as opposed to the
 * standard page-load way.
 *
 * This method attempts to mimic the functionality of the original form
 * as best as possible (duplicating the method, action, and exact contents
 * of the form).
 *
 * There are three different resulting operations that can occur, after
 * your form has been submitted.
 *
 * 1. The form is submitted and a callback is fired, letting you know
 *    when it's done:
 *    $("form").ajaxSubmit(function(){
 *      alert("all done!");
 *    });
 *
 * 2. The form is submitted and the resulting HTML contents are injected
 *    into the page, at your specified location.
 *    $("form").ajaxSubmit("#destination");
 *
 * 3. The form is submitted and the results returned from the server are
 *    automatically executed (useful for having the server return more
 *    Javascript commands to execute).
 *    $("form").ajaxSubmit();
 *
 * Additionally, an optional pre-submit callback can be provided. If it,
 * when called with the contents of the form, returns false, the form will
 * not be submitted.
 *
 * Finally, both the URL and method of the form submission can be
 * overidden using the 'url' and 'mth' arguments.
 *
 * @param target   arg for the target id element to render
 * @param post_cb  callback after any results are returned
 * @param pre_cb   callback function before submission
 * @param url      form action override
 * @param mth      form method override
 * @return         "this" object
 * @see            ajaxForm(), serialize(), load(), $.ajax()
 * @author         Mark Constable (markc@renta.net)
 * @author         G. vd Hoven, Mike Alsup, Sam Collett, John Resig
 */
$.fn.ajaxSubmit = function(target, post_cb, pre_cb, url, mth) {
        if ( !this.vars ) this.serialize();
        
        if (pre_cb && pre_cb.constructor == Function && pre_cb(this.vars) === false) return;

        var f = this.get(0);
        var url = url || f.action || '';
        var mth = mth || f.method || 'POST';

        if (target && target.constructor == Function)
                $.ajax(mth, url, $.param(this.vars), target);
        else if (target && target.constructor == String)
                $(target).load(url, this.vars, post_cb);
        else {
                this.vars.push({name: 'evaljs', value: 1});
                $.ajax(mth, url, $.param(this.vars), function(r) {
                        eval(r.responseText);
                });
        }

        return this;
};

/**
 * This function can be used to turn any HTML form into a form
 * that submits using AJAX only.
 *
 * The purpose of using this method, instead of the ajaxSubmit()
 * and submit() methods, is to make absolutely sure that the
 * coordinates of <input type="image"/> elements are transmitted
 * correctly OR figuring out exactly which <input type="submit"/>
 * element was clicked to submit the form.
 *
 * If neither of the above points are important to you, then you'll
 * probably just want to stick with the simpler ajaxSubmit() function.
 *
 * Usage examples, similar to ajaxSubmit():
 *
 * 1. Just eval the results returned from the backend.
 *    $('#form-id').ajaxForm();
 *
 * 2. Render backend results directly to target ID (expects (x)HTML).
 *    $('#form-id').ajaxForm('#target-id');
 *
 * 3. Submit to backend URL (form action) then call this function.
 *    $('#form-id').ajaxForm(post_callback);
 *
 * 4. Load target ID with backend results then call a function.
 *    $('#form-id').ajaxForm('#target-id', post_callback);
 *
 * 5. Call a browser function (for validation) and then (optionally)
 *    load server results to target ID.
 *    $('#form-id').ajaxForm('#target-id', null, pre_callback);
 *
 * 6. Call validation function first then load server results to
 *    target ID and then also call a browser function.
 *    $('#form-id').ajaxForm('#target-id', post_callback, pre_callback);
 *
 * @param target   arg for the target id element to render
 * @param post_cb  callback after any results are returned
 * @param pre_cb   callback function before submission
 * @return         the jQuery Object
 * @type jQuery
 * @see            serialize(), ajaxSubmit()
 * @author         Mark Constable (markc@renta.net)
 * @author         G. vd Hoven, Mike Alsup, Sam Collett, John Resig
 */
$.fn.ajaxForm = function(target, post_cb, pre_cb) {
        return this.each(function(){
                $("input[@type=submit],input[@type=image]", this).click(function(ev){
                        this.form.clicked = this;
                        if (ev.offsetX != undefined) {
                                this.form.clicked_x = ev.offsetX;
                                this.form.clicked_y = ev.offsetY;
                        } else {
                                this.form.clicked_x = ev.pageX - this.offsetLeft;
                                this.form.clicked_y = ev.pageY - this.offsetTop;
                        }
                });
        }).submit(function(e){
                $(this).ajaxSubmit(target, post_cb, pre_cb);
                return false;
        });
};

/**
 * A simple wrapper function that sits around the .serialize()
 * method, allowing you to easily extract the data stored within
 * a form.
 *
 * Usage examples:
 *
 * 1. Serialize the contents of a form to a & and = delmited string:
 *    $.param( $("form").formdata() );
 *
 * @return         An array of name/value pairs representing the form
 * @type Array<Object>
 * @see            serialize()
 # @author         John Resig
 */
$.fn.formdata = function(){
        this.serialize();
        return this.vars;
};

/**
 * This function gathers form element variables into an array that
 * is embedded into the current "this" variable as "this.vars". It
 * is normally used in conjunction with formdata() or ajaxSubmit() but can
 * be used standalone as long as you don't need the x and y coordinates
 * associated with an <input type="image"/> element..
 *
 * Standalone usage examples:
 *
 * 1. Gather form vars and return array to LHS variable.
 *    var myform = $('#form-id').serialize();
 *
 * 2. Provide a serialized URL-ready string (after 1. above).
 *    var mystring = $.param(myform.vars);
 *
 * 3. Gather form vars and send to RHS plugin via "this.vars".
 *    $('#form-id').serialize().some_other_plugin();
 *
 * @return         the jQuery Object
 * @return jQuery
 * @see            ajaxForm(), ajaxSubmit()
 * @author         Mark Constable (markc@renta.net)
 * @author         G. vd Hoven, Mike Alsup, Sam Collett, John Resig
 */
$.fn.serialize = function() {
        var a = [];
        var ok = {INPUT:true, TEXTAREA:true, OPTION:true};

        $('*', this).each(function() {
                var par = this.parentNode;
                var p = par.nodeName.toUpperCase();
                var n = this.name || p == 'OPTGROUP' && par.parentNode.name || p == 'SELECT' && par.name || this.id;

                if ( !n || this.disabled || this.type == 'reset' || 
                        (this.type == 'checkbox' || this.type == 'radio') && !this.checked || 
                        !ok[this.nodeName.toUpperCase()] ||
                        (this.type == 'submit' || this.type == 'image') && this.form.clicked != this ||
                        (p == 'SELECT' || p == 'OPTGROUP') && !this.selected ) return;

                if (this.type == 'image' && this.form.clicked_x)
                        return a.push(
                                {name: this.name+'_x', value: this.form.clicked_x},
                                {name: this.name+'_y', value: this.form.clicked_y}
                        );

                a.push({name: n, value: this.value});
        }).end();
        
        this.vars = a;

        return this;
};