<?php
    if (!defined('CHYRP_VERSION'))
        exit;
?>
var ChyrpAjaxScroll = {
    busy: false,
    failed: false,
    container: null,
    auto: <?php esce($config->module_cascade["ajax_scroll_auto"]); ?>,
    init: function() {
        ChyrpAjaxScroll.container = $(".post").last().parent()[0];

        if (typeof ChyrpAjaxScroll.container === "undefined")
            return;

        if (ChyrpAjaxScroll.auto)
            $(window).on("scroll", window, ChyrpAjaxScroll.watch);
        else
            $("#pagination_next_page").click(ChyrpAjaxScroll.click);

        if ("ariaLive" in ChyrpAjaxScroll.container)
            ChyrpAjaxScroll.container.ariaLive = "polite";

        if ("ariaAtomic" in ChyrpAjaxScroll.container)
            ChyrpAjaxScroll.container.ariaAtomic = "false";

        if ("ariaRelevant" in ChyrpAjaxScroll.container)
            ChyrpAjaxScroll.container.ariaRelevant = "additions";

        if ("ariaBusy" in ChyrpAjaxScroll.container)
            ChyrpAjaxScroll.container.ariaBusy = "false";
    },
    click: function(e) {
        if (!ChyrpAjaxScroll.failed) {
            e.preventDefault();
            ChyrpAjaxScroll.fetch();
        }
    },
    watch: function() {
        var docViewTop = $(window).scrollTop();
        var winHeight = window.innerHeight ? window.innerHeight : $(window).height();
        var docHeight = $(document).height();
        var docViewBottom = docViewTop + winHeight;

        // Trigger fetch on scroll when 8/10 of the page has been viewed.
        if (docViewBottom >= (docHeight * 0.8))
            ChyrpAjaxScroll.fetch();
    },
    fetch: function() {
        if (!ChyrpAjaxScroll.busy && !ChyrpAjaxScroll.failed) {
            ChyrpAjaxScroll.busy = true;

            if ("ariaBusy" in ChyrpAjaxScroll.container)
                ChyrpAjaxScroll.container.ariaBusy = "true";

            var this_post_obj = $(".post").last();
            var this_next_obj = $("#pagination_next_page");
            var this_next_url = this_next_obj.attr("href");

            if (this_next_url && this_post_obj.length) {
                $.get(
                    this_next_url,
                    function(data) {
                        var this_next_num = Number(this_next_url.match(/page[=\/]([0-9]+)/i)[1]);
                        var ajax_next_obj = $(data).find("#pagination_next_page");
                        var ajax_next_title = $(data).filter("title").text();

                        // Insert new posts and update page title.
                        this_post_obj.after($(data).find(".post"));
                        document.title = ajax_next_title;

                        // Update location history.
                        if (!!history.replaceState)
                            history.replaceState({
                                "page": this_next_num,
                                "action": Route.action
                            }, ajax_next_title, this_next_url);

                        // Replace #pagination_next_page if a replacement is found.
                        if (ajax_next_obj) {
                            this_next_obj.replaceWith(ajax_next_obj);
                            ChyrpAjaxScroll.busy = false;

                            if (!ChyrpAjaxScroll.auto)
                                $("#pagination_next_page").click(ChyrpAjaxScroll.click);
                        } else {
                            // That's all folks!
                            this_next_obj.remove();
                        }
                    },
                    "html"
                ).fail(ChyrpAjaxScroll.panic);
            }

            if ("ariaBusy" in ChyrpAjaxScroll.container)
                ChyrpAjaxScroll.container.ariaBusy = "false";
        }
    },
    panic: function() {
        ChyrpAjaxScroll.failed = true;
        Oops.count++;
        alert(Oops.message);
    }
};
$(document).ready(ChyrpAjaxScroll.init);