ns.page.js

(function() {

/**
 * Модуль управления "страницей" и переходами между ними.
 * @namespace
 */
ns.page = {};

/**
 * Current page params
 * @type {{page: string, params: Object}}
 */
ns.page.current = {};
ns.page.currentUrl = null;

ns.page._stop = false;
ns.page._lastUrl = '';

/**
 * Осуществляем переход по ссылке.
 * @param {String} [url=ns.page.getCurrentUrl()]
 * @param {Boolean} [preventAddingToHistory=false] Не добавлять урл в историю браузера.
 * @return {no.Promise}
 */
ns.page.go = function(url, preventAddingToHistory) {
    if (ns.page._stop) {
        ns.page._lastUrl = url;

        return no.Promise.rejected('transaction');
    }

    url = url || ns.page.getCurrentUrl();

    // возможность заблокировать переход
    if (!ns.page.block.check(url)) {
        // Если мы нажали кнопку "Назад" в браузере, то событие popstate произойдет уже после смены url
        // соответственно надо поменять урл на старый, если он поменялся
        if (url != ns.page.currentUrl) {
            ns.history.replaceState(ns.page.currentUrl);
        }
        return no.Promise.rejected('block');
    }

    var route = ns.router(url);

    // router says "redirect"
    if (route.page === ns.R.REDIRECT) {
        return ns.page.redirect(route.redirect);
    }

    if (route.page === ns.R.NOT_APP_URL) {
        if (preventAddingToHistory) {
            window.location.replace(route.redirect);
        } else {
            window.location = route.redirect;
        }

        // return empty non-resolved promise becase we are redirecting now
        return no.promise();
    }

    var layout = ns.layout.page(route.page, route.params);

    ns.events.trigger('ns-page-before-load', [ns.page.current, route]);

    ns.page.current = route;
    // save layout for async-view updates
    ns.page.current.layout = layout;
    ns.page.currentUrl = url;

    if (!preventAddingToHistory) {
        // записываем в историю все переходы
        ns.history.pushState(url);
    }

    ns.page.history.push(url);
    document.title = ns.page.title(url);

    var update = new ns.Update(ns.MAIN_VIEW, layout, route.params);
    return update.start();
};

/**
 * Redirects to given url.
 * @param {String} url New page url.
 * @returns {no.Promise}
 */
ns.page.redirect = function(url) {
    ns.history.replaceState(url);
    return ns.page.go(url, true);
};

/**
 * Returns document title.
 * @param {String} url Page URL.
 * @returns {string}
 */
ns.page.title = function(url) {
    return 'NoScript app ' + url;
};

/**
 * Module to add checkers and block proceed to another URL.
 * @namespace
 */
ns.page.block = {

    /**
     * Array of checkers
     * @private
     * @type {Function[]}
     */
    checkers: []
};

/**
 * Add function to check.
 * @param {Function} fn
 * @returns {ns.page.block}
 */
ns.page.block.add = function(fn) {
    ns.page.block.checkers.push(fn);

    return this;
};

/**
 * Remove function to check.
 * @param {Function} fn
 * @returns {ns.page.block}
 */
ns.page.block.remove = function(fn) {
    var index = ns.page.block.checkers.indexOf(fn);
    if (index > -1) {
        ns.page.block.checkers.splice(index, 1);
    }

    return this;
};

/**
 * Detect if possible to go to the url.
 * You can add your own checkers with ns.page.block.add(checkerFn)
 * @param {String} url URL to go.
 * @returns {Boolean}
 */
ns.page.block.check = function(url) {
    var checkers = ns.page.block.checkers;
    for (var i = 0, j = checkers.length; i < j; i++) {
        if (checkers[i](url) === false) {
            return false;
        }
    }

    return true;
};

/**
 * Returns default url for NoScript application.
 * Should be redefined.
 */
ns.page.getDefaultUrl = function() {
    return ns.router.url('/');
};

/**
 * Calculates current application url, fed as default value for `ns.page.go`.
 */
ns.page.getCurrentUrl = function() {
    return window.location.pathname + window.location.search;
};

/**
 * Object to work with application history.
 * @namespace
 */
ns.page.history = {};

/**
 * Current application url.
 * @type {string}
 * @private
 */
ns.page.history._current = null;

/**
 * History of application urls.
 * @type {Array}
 * @private
 */
ns.page.history._history = [];

/**
 * Saves url in history.
 * @param {string} url
 */
ns.page.history.push = function(url) {
    var nsHistory = ns.page.history;

    // save previous url to history
    if (nsHistory._current) {

        // prevent duplicates
        if (nsHistory._current !== url) {
            var prevPage = ns.page.history.getPrevious();

            // user pressed back button in browser
            if (prevPage == url) {
                nsHistory._history.pop();

            } else {
                nsHistory._history.push(nsHistory._current);
            }
        }
    }

    nsHistory._current = url;
};

/**
 * Go to previous page and delete it from history.
 * @returns {no.Promise}
 */
ns.page.history.back = function() {
    var nsHistory = ns.page.history;

    var previousPage = nsHistory.getPrevious();
    if (previousPage) {
        // removes last entry
        nsHistory._history.pop();

    } else {
        // get default url
        previousPage = ns.page.getDefaultUrl();
    }

    // delete current history url
    nsHistory._current = previousPage;

    return ns.page.go(previousPage);
};

/**
 * Returns previous page.
 * @param {number} [n=0] N pages ago
 * @returns {string}
 */
ns.page.history.getPrevious = function(n) {
    n = n || 0;
    var history = ns.page.history._history;
    var l = history.length;
    // Предыдущая страница, если есть.
    return history[l - n - 1];
};

})();