// ==UserScript==
// @name           GPForums Youtube Autoplay
// @namespace      awt
// @description    Autoplay embedded YouTube clips one at a time
// @include        http://www.gpforums.co.nz/*
// ==/UserScript==


/* Define all unsafeWindow functions before the rest of script (thanks ED) */

unsafeWindow.onYouTubePlayerReady = function(playerid){

    if (unsafeWindow.totalNo == undefined){
        unsafeWindow.totalNo = 0;
    } else {
        unsafeWindow.totalNo++;
    }

    player = document.getElementById(playerid).wrappedJSObject;
    // Add Event Listener for State Change and for situation where a video errors.
    player.addEventListener("onStateChange", "whenStateChanges");
    player.addEventListener("onError", "whenError");

    if (unsafeWindow.totalNo == unsafeWindow.totalClips) {
        alert(unsafeWindow.totalClips + " YouTube clips lined up. Starting first video now.");
        unsafeWindow.currentPlayer = 0;
        player = document.getElementById("0").wrappedJSObject.playVideo();
    }
}


unsafeWindow.whenStateChanges = function(state) {
    if (state == 0){ // Called when clip ends (state = 0)
        unsafeWindow.nextClip();
    }
}

unsafeWindow.whenError = function() {
    // Called if a clip doesn't play due to an error
    unsafeWindow.nextClip();
}

// Plays the next unique clip on the page
unsafeWindow.nextClip = function(){
    unsafeWindow.currentPlayer++;
    document.getElementById(unsafeWindow.currentPlayer).wrappedJSObject.playVideo();
    unsafeWindow.scrollTo(0, (unsafeWindow.getOffset( document.getElementById(unsafeWindow.currentPlayer) ).top - 200));
}

// To get the XY coordinates of an element
// ** Thanks to meouw and cwallenpoole at stackoverflow **
unsafeWindow.getOffset = function(el) {
    var _x = 0;
    var _y = 0;
    while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
        _x += el.offsetLeft - el.scrollLeft;
        _y += el.offsetTop - el.scrollTop;
        el = el.offsetParent;
    }
    return { top: _y, left: _x };
}




/* Initial script to detect embedded clips, remove duplicates, and re-embed with desired attributes */

var nodeList = document.getElementsByTagName("embed"); // Get all embedded objects

// Convert NodeList "nodeList" to an Array of Nodes "objects"
var objects = new Array();
for (i=0;i<nodeList.length;i++){
   objects.push(nodeList[i]);
}

// Ensure embedded objects are YouTube, remove duplicates, and re-embed the objects with desired changes.
for (i=0; i<objects.length; i++) {
   var stringA;
   var stringB;

   // Get source of the embedded object
   var attributes = objects[i].attributes;
   var source = attributes.getNamedItem("src");

   // Checks that embedded file is youtube.  **Don't know if this works, haven't come across any non-youtube embeds.**
   if (source == -1|| source.nodeValue.indexOf("http://www.youtube.com/v/") == -1) {
      alert("Non-YouTube embedded object found");
      // ... and will need to write something else here, if this situation ever arises.
   }

    // Ensure each equivalent (same source) object is only present once in the array.
    stringA = source.nodeValue;
    for (j=0; j<objects.length; j++) {
        var compAttributes = objects[j].attributes;
        var compSource = compAttributes.getNamedItem("src");

        stringB = compSource.nodeValue;

        if (stringA == stringB &&  !(i==j) ){ // If same source but not the same index
           objects.splice(j,1);
           j--; // array length changed by splice, so need to re-check this index
        }
    }

    // Re-embed the YT clips, enabling the JS API, giving each a unique ID
    objects[i].setAttribute("src", objects[i].getAttribute("src").concat("&enablejsapi=1&playerapiid=" + i));
    // Put an "id" atribute in <embed>
    objects[i].setAttribute("id", i);
}

// "Pass" number of unique clips to the unsafeWindow namespace
unsafeWindow.totalClips = objects.length - 1;