/* --------------------------------------------------------------
 form_changes_checker.js 2015-10-15 gm
 Gambio GmbH
 http://www.gambio.de
 Copyright (c) 2015 Gambio GmbH
 Released under the GNU General Public License (Version 2)
 [http://www.gnu.org/licenses/gpl-2.0.html]
 --------------------------------------------------------------
 */

/**
 * ## From Changes Checker Extension
 *
 * Stores all form data inside $(this) an waits for an trigger to compare the data with the
 * original. A, with the trigger delivered deferred object gets resolved or rejected depending
 * on the result.
 *
 * @todo Create some jQuery selector methods so that it is easier to check if something was changed.
 * @todo The extension must add a 'changed' or 'updated' class to the form so that other modules or code can determine
 * directly that something was changed.
 * @todo If a value is changed inside a input/select/textarea element this plugin must automatically perform the check.
 * Currently it just waits for the consumers to call the 'formchanges.check' event.
 *
 * @module Admin/Extensions/form_changes_checker
 * @ignore
 */
gx.extensions.module(
    'form_changes_checker',

    ['form'],

    function (data) {

        'use strict';

        // ------------------------------------------------------------------------
        // VARIABLE DEFINITION
        // ------------------------------------------------------------------------

        var
            /**
             * Extension Reference
             *
             * @type {object}
             */
            $this = $(this),

            /**
             * Default Options for Extension
             *
             * @type {object}
             */
            defaults = {
                'ignoreClass': '.ignore_changes'
            },

            /**
             * Final Extension Options
             *
             * @type {object}
             */
            options = $.extend(true, {}, defaults, data),

            /**
             * Initial Form Data
             *
             * @type {array}
             *
             * @todo Replace the initial value to an object.
             */
            formData = [],

            /**
             * Module Object
             *
             * @type {object}
             */
            module = {};

        // ------------------------------------------------------------------------
        // EVENT HANDLER
        // ------------------------------------------------------------------------

        /**
         * Check Forms
         *
         * Function to compare the original data with the data that is currently in the
         * form. the given deferred object gets resolved or rejected.
         *
         * @param {object} event jQuery event object
         * @param {object} deferred JSON object containing the deferred object.
         */
        var _checkForms = function (event, deferred) {
            event.stopPropagation();

            deferred = deferred.deferred;

            var newData = jse.libs.form.getData($this, options.ignoreClass),
                cache = JSON.stringify(formData),
                current = JSON.stringify(newData),
                returnData = {
                    'original': $.extend({}, formData),
                    'current': $.extend({}, newData)
                };

            if (cache === current) {
                deferred.resolve(returnData);
            } else {
                deferred.reject(returnData);
            }
        };

        // ------------------------------------------------------------------------
        // INITIALIZATION
        // ------------------------------------------------------------------------

        /**
         * Init function of the extension, called by the engine.
         */
        module.init = function (done) {

            formData = jse.libs.form.getData($this, options.ignoreClass);
            $this
                .on('formchanges.check', _checkForms)
                .on('formchanges.update', function () {
                    // Updates the form data stored in cache
                    formData = jse.libs.form.getData($this, options.ignoreClass);
                });

            $('body').on('formchanges.check', function (e, d) {
                // Event listener that performs on every formchanges.check trigger that isn't handled
                // by the form_changes_checker
                if (d && d.deferred) {
                    d.deferred.resolve();
                }
            });

            done();
        };

        // Return data to module engine.
        return module;
    });