NodeBB/NodeBB

'use strict';

define('handleBack', [
    'components',
    'storage',
    'navigator',
    'forum/pagination',
], function (components, storage, navigator, pagination) {
    const handleBack = {};
    let loadTopicsMethod;

    handleBack.init = function (_loadTopicsMethod) {
        loadTopicsMethod = _loadTopicsMethod;
        saveClickedIndex();
        $(window).off('action:popstate', onBackClicked).on('action:popstate', onBackClicked);
    };

    handleBack.onBackClicked = onBackClicked;

    function saveClickedIndex() {
        $('[component="category"]').on('click', '[component="topic/header"]', function () {
            const clickedIndex = $(this).parents('[data-index]').attr('data-index');
            const windowScrollTop = $(window).scrollTop();
            $('[component="category/topic"]').each(function (index, el) {
                if ($(el).offset().top - windowScrollTop > 0) {
                    storage.setItem('category:bookmark', $(el).attr('data-index'));
                    storage.setItem('category:bookmark:clicked', clickedIndex);
                    storage.setItem('category:bookmark:offset', $(el).offset().top - windowScrollTop);
                    return false;
                }
            });
        });
    }

    function onBackClicked(isMarkedUnread) {
        const highlightUnread = isMarkedUnread && ajaxify.data.template.unread;
        if (
            ajaxify.data.template.category ||
            ajaxify.data.template.recent ||
            ajaxify.data.template.popular ||
            highlightUnread
        ) {
            let bookmarkIndex = storage.getItem('category:bookmark');
            let clickedIndex = storage.getItem('category:bookmark:clicked');

            storage.removeItem('category:bookmark');
            storage.removeItem('category:bookmark:clicked');
            if (!utils.isNumber(bookmarkIndex)) {
                return;
            }

            bookmarkIndex = Math.max(0, parseInt(bookmarkIndex, 10) || 0);
            clickedIndex = Math.max(0, parseInt(clickedIndex, 10) || 0);

            if (config.usePagination) {
                const page = Math.ceil((parseInt(bookmarkIndex, 10) + 1) / config.topicsPerPage);
                if (parseInt(page, 10) !== ajaxify.data.pagination.currentPage) {
                    pagination.loadPage(page, function () {
                        handleBack.scrollToTopic(bookmarkIndex, clickedIndex);
                    });
                } else {
                    handleBack.scrollToTopic(bookmarkIndex, clickedIndex);
                }
            } else {
                if (bookmarkIndex === 0) {
                    handleBack.scrollToTopic(bookmarkIndex, clickedIndex);
                    return;
                }

                $('[component="category"]').empty();
                loadTopicsMethod(Math.max(0, bookmarkIndex - 1) + 1, function () {
                    handleBack.scrollToTopic(bookmarkIndex, clickedIndex);
                });
            }
        }
    }

    handleBack.highlightTopic = function (topicIndex) {
        const highlight = components.get('category/topic', 'index', topicIndex);

        if (highlight.length && !highlight.hasClass('highlight')) {
            highlight.addClass('highlight');
            setTimeout(function () {
                highlight.removeClass('highlight');
            }, 5000);
        }
    };

    handleBack.scrollToTopic = function (bookmarkIndex, clickedIndex) {
        if (!utils.isNumber(bookmarkIndex)) {
            return;
        }

        const scrollTo = components.get('category/topic', 'index', bookmarkIndex);

        if (scrollTo.length) {
            const offset = storage.getItem('category:bookmark:offset');
            storage.removeItem('category:bookmark:offset');
            $(window).scrollTop(scrollTo.offset().top - offset);
            handleBack.highlightTopic(clickedIndex);
            navigator.update();
        }
    };

    return handleBack;
});