/* --------------------------------------------------------------
 dynamic_shop_messages.js 2016-05-11
 Gambio GmbH
 http://www.gambio.de
 Copyright (c) 2016 Gambio GmbH
 Released under the GNU General Public License (Version 2)
 [http://www.gnu.org/licenses/gpl-2.0.html]
 --------------------------------------------------------------
 */

/**
 * ## Dynamic Shop Messages
 *
 * This extension module is meant to be executed once in every page load. Its purpose is to display
 * custom notifications into various positions of the HTML. The notification source may vary in each
 * case but the original data should come from Gambio's Customer Portal.
 *
 * The module supports the use of a "url" option which will be used for loading the JSON data through an
 * AJAX call.
 *
 * ### Options
 *
 * **Data Source URL | `data-dynamic_shop_messages-url` | String | Optional**
 *
 * Provide the URL which will be used to fetch the dynamic shop messages. By default the DynamicShopMessages
 * controller will be used.
 *
 * **Response Envelope | `data-dynamic_shop_messages-response-envelope` | String | Optional**
 *
 * Set a custom response envelop for the response object. By default "MESSAGES" will be used, because this is
 * the envelope from the Gambio Portal response.
 *
 * ### Example
 *
 * ```html
 * <div data-gx-extension="dynamic_shop_messages"
 *     data-dynamic_shop_messages-url="http://custom-url.com/myscript.php"
 *     data-dynamic_shop_messages-response-envelope="MESSAGES">
 *   <-- HTML CONTENT -->
 * </div>
 * ```
 *
 * @module Admin/Extensions/dynamic_shop_messages
 * @ignore
 */
gx.extensions.module(
    'dynamic_shop_messages',

    [],

    function (data) {

        'use strict';

        // ------------------------------------------------------------------------
        // VARIABLES
        // ------------------------------------------------------------------------

        let
            /**
             * Module Selector
             *
             * @type {object}
             */
            $this = $(this),

            /**
             * Default Options
             *
             * @type {object}
             */
            defaults = {
                url: jse.core.config.get('appUrl') + '/admin/admin.php?do=DynamicShopMessages',
                lifetime: 30000, // maximum search lifetime (ms)
                responseEnvelope: 'MESSAGES'
            },

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

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

        // ------------------------------------------------------------------------
        // FUNCTIONS
        // ------------------------------------------------------------------------

        /**
         * Checks if an HTML markup string is valid.
         *
         * {@link http://stackoverflow.com/a/14216406}
         *
         * @param {string} html The HTML markup to be validated.
         *
         * @returns {bool} Returns the validation result.
         */
        var _validateHtml = function (html) {
            var doc = document.createElement('div');
            doc.innerHTML = html;
            return (doc.innerHTML === html);
        };

        /**
         * Check the current page matches the target_page value of the JSON data.
         *
         * @param {string|array} targetPageValue Contains a URL string or an array of URLs to be matched.
         *
         * @return {bool} Returns the validation check.
         */
        var _checkTargetPage = function (targetPageValue) {
            var result = false;

            if (typeof targetPageValue !== 'object') {
                targetPageValue = [targetPageValue];
            }

            $.each(targetPageValue, function () {
                var regex = new RegExp(this);

                if (window.location.href === jse.core.config.get('appUrl') + '/admin/' + this
                    || regex.test(window.location.href)) {
                    result = true;
                    return false; // exit loop
                }
            });

            return result;
        };

        /**
         * Try to apply the dynamic message data into the page.
         *
         * @param {array} messages
         */
        var _apply = function (messages) {
            $.each(messages, function (index, entry) {
                try {
                    // Check if we have target information in the message entry.
                    if (entry.target_page === undefined || entry.target_selector === undefined) {
                        throw new TypeError('No target information provided. Skipping to the next entry...');
                    }

                    // Check if we are in the target page.
                    if (!_checkTargetPage(entry.target_page)) {
                        throw new TypeError(
                            'The entry is not targeted for the current page. Skipping to the next entry...');
                    }

                    // Find the target selector and append the HTML message. The module will keep on searching
                    // for the target selector for as long as the "options.lifetime" value is.
                    var currentTimestamp = Date.now;

                    var intv = setInterval(function () {
                        var $target = $this.find(entry.target_selector);

                        if ($target.length > 0) {
                            var htmlBackup = $target.html();
                            $target.append(entry.message);

                            // Check if the current HTML is valid and revert it otherwise.
                            if (!_validateHtml($target.html())) {
                                $target.html(htmlBackup);
                                jse.core.debug.error('Dynamic message couldn\'t be applied.', entry);
                            }

                            clearInterval(intv); // stop searching
                        }

                        if (Date.now - currentTimestamp > options.lifetime) {
                            clearInterval(intv);
                            throw Error(
                                'Search lifetime limit exceeded, no element matched the provided selector.');
                        }
                    }, 300);

                } catch (e) {
                    return true; // Continue loop with next message entry.
                }
            });
        };

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

        module.init = function (done) {
            $(document).on('JSENGINE_INIT_FINISHED', function () {
                $.getJSON(options.url)
                    .done(function (response) {
                        _apply(response[options.responseEnvelope]);
                    })
                    .fail(function (jqXHR, textStatus, errorThrown) {
                        jse.core.debug.info('Could not load the dynamic shop messages.', jqXHR, textStatus,
                            errorThrown);
                    });
            });

            done();
        };

        return module;
    });