Resize YT To Window Size (Scrollbar fix rev.)

// ==UserScript==
// @name            Resize YT To Window Size
// @description     Moves the video to the top of the website and resizes it to the screen size.
// @author          Chris H (Zren / Shade)
// @icon            http://youtube.com/favicon.ico
// @homepageURL     http://userscripts.org/scripts/show/153699
// @downloadURL     http://userscripts.org/scripts/source/153699.user.js
// @updateURL       http://userscripts.org/scripts/source/153699.meta.js
// @namespace       http://xshade.ca
// @version         1.11
// @include         http*://*.youtube.com/watch?*
// @include         http*://youtube.com/watch?*
// ==/UserScript==

/*
** Youtube Layout lookup
**

[? - 20 March 2013]
#watch7-video-container (#watch7-playlist-container is injected above this element)
  #watch7-video
    #watch-player ?
      embed#movie_player ?

[20 March 2013]
  #watch7-video-container --renamed--> #watch7-container (renamed back then?)

#player (#watch7-playlist-container is injected above this element)
  #player-api
    embed#movie_player
  #watch7-creator-bar

[2 April 2013]
  #watch7-playlist-container --renamed--> #playlist

[3 May 2013]
  .watch-playlist-collapsed and .watch-medium now attach to #player

#watch7-container .watch-playlist
  #player .watch-playlist-collapsed .watch-medium (moved)
    #playlist (Moved to inside #player)
      #watch7-playlist-scrollfloater
        #watch7-playlist-bar
      #watch7-playlist-data
        #watch7-playlist-bar
#watch7-main-container
  ...

*/

(function () {
    "use strict";

    //--- Constants
    var scriptShortName = 'ytwp'; // YT Window Player
    var injectedStyleId = scriptShortName + '-style';
    var scriptBodyClassId = scriptShortName + '-window-player';
    var scriptBodyClassSelector = 'body.' + scriptBodyClassId;

    var transitionProperties = ["transition", "-ms-transition", "-moz-transition", "-webkit-transition", "-o-transition"];

    //--- Utils
    function isStringType(obj) {
        return typeof obj === 'string';
    }

    function isArrayType(obj) {
        return obj instanceof Array;
    }

    function isObjectType(obj) {
        return typeof obj === 'object';
    }

    function isUndefined(obj) {
        return typeof obj === 'undefined';
    }

    function buildCSS(selector, styles) {
        var s = "";
        for (var key in styles) {
            s += "\t" + key + ": " + styles[key] + ";\n";
        }
        return selector + " {\n" + s + "}\n";
    }


    function appendStyle(selector, k, v) {
        var newStyle;
        if (!isUndefined(k) && !isUndefined(v) && isStringType(k)) { // v can be any type (as we stringify it).
            // appendStyle('#blarg', 'display', 'none');
            var d = {};
            d[k] = v;
            newStyle = buildCSS(selector, d);
        } else if (!isUndefined(k) && isUndefined(v) && isObjectType(k)) {
            // appendStyle('#blarg', {'display': 'none'});
            newStyle = buildCSS(selector, k);
        } else {
            // Invalid Arguments
            console.log('Illegal arguments', selector, k, v);
            return;
        }

        var styleElement = document.getElementById(injectedStyleId);
        if (!styleElement) {
            styleElement = document.createElement('style');
            styleElement.type = 'text/css';
            styleElement.id = injectedStyleId;
            document.getElementsByTagName('head')[0].appendChild(styleElement);
        }
        styleElement.appendChild(document.createTextNode(newStyle));
    }

    function buildVenderPropertyDict(propertyNames, value) {
        var d = {};
        for (var i in propertyNames)
            d[propertyNames[i]] = value;
        return d;
    }

    //---

    function moveVideoContainer() {
        //--- Video Container
        var videoContainer = document.getElementById("player-api");

        // Make sure YT hasn't changed or on a page without a video player.
        if (!videoContainer) return 0;

        // Move the video to the top of page.
        var body = document.body;
        body.insertBefore(videoContainer, body.firstChild);

        return 1;
    }

    function resizeVideoPlayer() {
        //--- Video Player

        //
        var d = buildVenderPropertyDict(transitionProperties, 'left 0s linear, padding-left 0s linear');

        appendStyle(scriptBodyClassSelector + ' #player', d);

        //
        var d = buildVenderPropertyDict(transitionProperties, 'width 0s linear, left 0s linear');
        appendStyle(scriptBodyClassSelector + ' #player-api', d);

        // !important is mainly for simplicity, but is needed to override the !important styling when the Guide is open due to:
        // .sidebar-collapsed #watch7-video, .sidebar-collapsed #watch7-main, .sidebar-collapsed .watch7-playlist { width: 945px!important; }
        appendStyle(
            scriptBodyClassSelector + ' #player-api, ' + scriptBodyClassSelector + ' #movie_player',
            {
                'width': '100% !important',
                'height': '100% !important'
            }
        );


        //--- Sidebar

        // Remove the transition delay as you can see it moving on page load.
        var d = buildVenderPropertyDict(transitionProperties, 'margin-top 0s linear, padding-top 0s linear');

        // Override sidebar position. It changes according to the video player's size.
        // Small video player state has: margin-top: -390px; which overlaps the video.
        d['margin-top'] = '15px !important'; // Large video player has 15px padding-top.
        appendStyle(scriptBodyClassSelector + ' #watch7-sidebar', d);

        //--- Fix Other Possible Style Issues

        //--- Whitespace Leftover From Moving The Video
        appendStyle(scriptBodyClassSelector + ' #page.watch', 'padding-top', '0');

        //--- Video Manager (When viewing own videos)
        appendStyle('#body-container', 'clear', 'both'); // FF needs this
        appendStyle('#watch7-creator-bar', {
            'position': 'relative', // Needed in order to use z-index
            'z-index': '2', // #guide.zIndex + 1
        });

        //--- Playlist Bar
        // Set the playlist bar width when large to the same as when small (so it expands over the sidebar).
        appendStyle(scriptBodyClassSelector + ' #watch7-playlist-data .watch7-playlist-bar', 'width', '945px !important');
        appendStyle(scriptBodyClassSelector + ' #watch7-playlist-bar-toggle-button', 'display', 'inline');

        //--- Playlist Bar: Youtube Center Overrides (Temporary)
        // Fix padding on the playlist bar when using 'Center Page'.
        appendStyle(scriptBodyClassSelector + '.ytcenter-site-watch.ytcenter-site-center .watch7-playlist', 'padding-left', '0');
        appendStyle(scriptBodyClassSelector + '.ytcenter-site-watch.ytcenter-site-center.guide-collapsed .watch7-playlist', 'padding-left', '0 !important');

        //--- Playlist Bar: Sidebar
        // Override sidebar position at element level. It changes according to the video player's size.
        //#watch7-playlist-tray-container { height: 363px; }
        //#watch7-playlist-tray { border-bottom: 27px solid #1B1B1B; }
        // Needs to be !important as it needs to override when on a non-playlist page (which requires !important).
        appendStyle(scriptBodyClassSelector + ' #watch7-container.watch-playlist #player.watch-playlist-collapsed+#watch7-main-container #watch7-sidebar', 'margin-top', '0px !important');
        appendStyle(scriptBodyClassSelector + ' #watch7-container.watch-playlist #player:not(.watch-playlist-collapsed)+#watch7-main-container #watch7-sidebar', 'margin-top', '390px !important');
        appendStyle(scriptBodyClassSelector + ' #watch7-container.watch-playlist #player.watch-medium:not(.watch-playlist-collapsed)+#watch7-main-container #watch7-sidebar', 'margin-top', '480px !important');

        fixScrollbars(); // Added content

        return 1;
    }

    function addBodyClass() {
        // Insert CSS Into the body so people can style around the effects of this script.
        document.body.classList.add(scriptBodyClassId);

        return 1;
    }

    function main() {
        oldVerticalPosition = window.pageYOffset;
        moveVideoContainer()
            && resizeVideoPlayer()
            && addBodyClass() // Only add class if found & moved the player.
            && initScrollbarFix(); // Added content
    }

    // Added content below (START)
    var oldVerticalPosition;
    function initScrollbarFix() {
        oldVerticalPosition = -1;
        setInterval(fixScrollbars, 1000);
        return 1;
    }

    function fixScrollbars() {
        if(oldVerticalPosition != window.pageYOffset) {
            oldVerticalPosition = window.pageYOffset;
            appendStyle('body', 'overflow-x', window.pageYOffset == 0 ? 'hidden' : 'visible');
            //appendStyle('body', 'overflow-y', window.pageYOffset == 0 ? 'hidden' : 'visible'); // Unforunately, it (partially) locks up the vertical scrolling
        }
    }
    // Added content (END)

    main();

})();