/*jslint browser: true, indent: 4 */
/*global updateCanvas: true */
(function (g) {
    "use strict";
    var lookForNextPage,
        getNextPage,
        appendContent,
        loadManually,
        manual,
        loader,
        working;

    if (g.ScrollGuard === undefined) {
        throw new Error("scrollguard.js is required!");
    }

    appendContent = function (content) {
        var body, rows, i, max, newContent, table;
        body = document.createElement("div");
        body.innerHTML = content;

        newContent = document.createDocumentFragment();
        rows = body.querySelectorAll(".main-c table tr");

        for (i = 1, max = rows.length; i < max; i += 1) {
            newContent.appendChild(rows[i]);
        }

        table = document.querySelector(".main-c table").tBodies[0];
        table.replaceChild(newContent, table.querySelector("tr.pagination"));

        if (typeof(updateCanvas) === "function") {
            updateCanvas();
        }

        loadManually();
    };

    loadManually = function () {
        var button;

        button = document.getElementById("load-manually");

        if (button) {
            if (!document.getElementById("pager-next")) {
                button.parentNode.removeChild(button);
            }

            button.onclick = function () {
                var nextPage = document.getElementById("pager-next");
                
                if (nextPage) {
                    getNextPage(nextPage.href);
                    button.parentNode.replaceChild(loader.cloneNode(), button);
                }
            };
        }
    };

    manual = function () {
        var style, elm;

        elm = document.getElementById("load-manually");

        if (!elm) { return false; }

        style = window.getComputedStyle(elm, null);
        return style.getPropertyValue("display") !== "none";
    };

    lookForNextPage = function () {
        if (!manual()) {
            var nextPage = document.getElementById("pager-next");

            if (nextPage) {
                getNextPage(nextPage.href);
            }
        }
    };

    getNextPage = function (href) {
        var request = new XMLHttpRequest();

        if (working === true) {
            return;
        }

        working = true;

        request.onreadystatechange = function () {
            if (request.readyState === 4) {
                working = false;
                if (request.status === 200 || request.status === 304) {
                    appendContent(request.responseText);
                }
            }
        };

        request.open("GET", href, true);
        request.send(null);
    };

    loadManually();

    loader = document.createElement("img");
    loader.style.paddingTop = "14px";
    loader.src = "/templates/wide/css/images/loader.gif";

    if (document.getElementById("pager-next")) {
        g.ScrollGuard.add(lookForNextPage, -1);
        g.ScrollGuard.start();
    }
}(this));