// ==UserScript==
// @name           Folksemantic Recommender
// @namespace      folksemantic.com
// @description    Displays links to resources related to the web page a user is looking at.
// @include        *
// ==/UserScript==

var sUrlToGetRecsFor = new String(window.location);
if (self != top && !folksemanticFrames(sUrlToGetRecsFor)) return;

var Drag = function() {
    this.init.apply(this, arguments);
};

Drag.fixE = function(e) {
    if (typeof e == 'undefined') e = window.event;
    if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
    if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
    return e;
};

Drag.prototype.init = function(handle, dragdiv) {
    this.div = dragdiv || handle;
    this.handle = handle;
    if (isNaN(parseInt(this.div.style.left))) this.div.style.left = '0px';
    if (isNaN(parseInt(this.div.style.top))) this.div.style.top = '0px';
    this.onDragStart = function() {};
    this.onDragEnd = function() {};
    this.onDrag = function() {};
    this.onClick = function() {};
    this.mouseDown = addEventHandler(this.handle, 'mousedown', this.start, this);
};

Drag.prototype.start = function(e) {
    e = Drag.fixE(e);

    this.started = new Date();
    var y = this.startY = parseInt(this.div.style.top);
    var x = this.startX = parseInt(this.div.style.left);
    this.onDragStart(x, y);
    this.lastMouseX = e.clientX;
    this.lastMouseY = e.clientY;
    this.documentMove = addEventHandler(document, 'mousemove', this.drag, this);
    this.documentStop = addEventHandler(document, 'mouseup', this.end, this);
    if (e.preventDefault) e.preventDefault();
    return false;
};

Drag.prototype.drag = function(e) {
    e = Drag.fixE(e);
    var ey = e.clientY;
    var ex = e.clientX;
    var y = parseInt(this.div.style.top);
    var x = parseInt(this.div.style.left);
    var nx = ex + x - this.lastMouseX;
    var ny = ey + y - this.lastMouseY;
    this.div.style.left = nx + 'px';
    this.div.style.top = ny + 'px';
    this.lastMouseX = ex;
    this.lastMouseY = ey;
    this.onDrag(nx, ny);
    if (e.preventDefault) e.preventDefault();
    return false;
};

Drag.prototype.end = function() {
    removeEventHandler(document, 'mousemove', this.documentMove);
    removeEventHandler(document, 'mouseup', this.documentStop);
    var time = (new Date()) - this.started;
    var x = parseInt(this.div.style.left),  dx = x - this.startX;
    var y = parseInt(this.div.style.top), dy = y - this.startY;
    this.onDragEnd(x, y, dx, dy, time);
    if ((dx * dx + dy * dy) < (4 * 4) && time < 1e3)
        this.onClick(x, y, dx, dy, time);
};

function removeEventHandler(target, eventName, eventHandler) {
    if (target.addEventListener)
        target.removeEventListener(eventName, eventHandler, true);
    else if (target.attachEvent)
        target.detachEvent('on' + eventName, eventHandler);
}

function addEventHandler(target, eventName, eventHandler, scope) {
    var f = scope ? function() {
        eventHandler.apply(scope, arguments);
    } : eventHandler;
    if (target.addEventListener)
        target.addEventListener(eventName, f, true);
    else if (target.attachEvent)
        target.attachEvent('on' + eventName, f);
    return f;
}

function dom_setStyle(elt, str) {
    elt.setAttribute("style", str);
    // for MSIE:
    if (elt.style.setAttribute) {
        elt.style.setAttribute("cssText", str, 0);
        // positioning for MSIE:
        if (elt.style.position == "fixed") {
            elt.style.position = "absolute";
        }
    }
}

function special_website_url(url) {
    // NEEDS
    if (url.indexOf("http://www.needs.org/") == 0)
    {
        bNeeds = true;
        if (url.length > 167 && url.indexOf("http://www.needs.org/needs/public/search/search_results/learning_resource/summary/index.jhtml") == 0)
        {
            bNeedsRecord = true;
            nHook = url.indexOf("?");
            if (nHook != -1)
            {
                url = "http://www.needs.org/needs/" + url.substring(nHook, url.length);
            }
        }
    }
    // eduCommons websites
    else if (document.getElementById("portlet-eduCommonsNavigation"))
    {
        bSpecialSite = true;
        var nEnd = url.indexOf("/", 20);
        if (nEnd != -1)
        {
            nEnd = url.indexOf("/", nEnd + 1);
            if (nEnd != -1)
            {
                url = url.substr(0, nEnd);
            }
        }
    }
    // MIT
    else if (url.indexOf("http://ocw.mit.edu/") == 0 && url.indexOf("http://ocw.mit.edu/OcwWeb/web") == -1)
        {
            bSpecialSite = true;
            bMIT = true;
            var nEnd = url.indexOf("/", 20);
            if (nEnd != -1)
            {
                nEnd = url.indexOf("/", nEnd + 1);
                if (nEnd != -1)
                {
                    nEnd = url.indexOf("/", nEnd + 1);
                    if (nEnd != -1)
                    {
                        url = url.substr(0, nEnd);
                    }
                }
            }
        }
    return encodeURI(url);
}

function getElementByClassName(sTagName, sClassName) {
    var aTags = document.getElementsByTagName(sTagName);
    for (var nTag = 0; nTag < aTags.length; nTag++)
    {
        if (sClassName == aTags[nTag].className) return aTags[nTag];
    }
    return null;
}

function identifySquatParent() {
    // educommons
    squatParent = document.getElementById("portlet-eduCommonsNavigation");
    if (squatParent) {
        squatSibling = squatParent.lastChild;
        divTags = squatParent.getElementsByTagName("div");
        lastDivTag = divTags[divTags.length - 1];
        sTopMargin = (lastDivTag.className == "currentSelection") ? "6px" : "0px";
        sLeftMargin = "0px";
        sRightMargin = "0px";
    } else {
        // MIT
        squatParent = document.getElementById("local_navigation");
        if (bMIT && squatParent) {
            ulTags = squatParent.getElementsByTagName("ul");
            if (ulTags)
            {
                ulTag = ulTags[0];
                if (ulTag) ulTag.style.margin = "0px 0px 6px;";
            }
            squatSibling = squatParent.lastChild;
            sLeftMargin = "6px";
            sRightMargin = "6px";
        }
        // everything else
        else {
             setDefaultSquatParent();
        }
    }
}

function setDefaultSquatParent() {
     if (document.body) {
         squatParent = document.body;
         squatSibling = document.body.firstChild;
	 bSpecialSite = false;
     }
}

String.prototype.startsWith = function(str) {
    return (this.match("^" + str) == str)
}

function demoDomain(sUrl) {
    for (nDomain = 0; nDomain < demoDomains.length; nDomain++) {
        if (sUrl.startsWith(demoDomains[nDomain])) return true;
    }
    return folksemanticFrames(sUrl);
}
function blacklistedDomain(sUrl) {
    for (nDomain = 0; nDomain < blacklistedDomains.length; nDomain++) {
        if (sUrl.indexOf(blacklistedDomains[nDomain]) != -1) return true;
    }
    return false;
}
function folksemanticFrames(sUrl) {
    return (sUrl.indexOf("show_recs=true") != -1);
}

function recList(recommendations, sDirectLinkText) {
    var sRecListDivStart = '<div id="recommenderlist" style="margin: 3px; padding: 0px;">';
    var sRecListDivEnd = '</div>';
    var sListStart = '<ul style="margin: 0px; padding: 0px; list-style-type: none;">';
    var sListEnd = '</ul>';
    var sRecList = bSpecialSite == true ? '' : sListStart;
    for (var i = 0; i < recommendations.length; i++)
    {
        // get info for the recommendation
        rec_title = recommendations[i].getElementsByTagName('title')[0].textContent;
        rec_link = recommendations[i].getElementsByTagName('link')[0].textContent;
        collection = recommendations[i].getElementsByTagName('collection')[0].textContent;
        rec_tag = '<a href="' + rec_link + '" style="color:#3987DC !important; text-decoration:none !important; " target="_top">' + rec_title + ' (' + collection + ')</a>';

        // our lists are different in educommons and on MIT's websites
        if (bSpecialSite == true)         {
            sRecList += "<p style='font-size:12px;padding-left:4px;'>";
            sRecList += rec_tag;
            sRecList += "</p>";
        } else {
            // default list styles
            sRecList += '<li style="margin-left: 0px; padding: 3px; list-style-type: none; font-size: 12px; ';
            if (i % 2 == 0) sRecList += 'background-color:#E6E6E6;';
            sRecList += '">';
            sRecList += rec_tag;
            sRecList += '</li>';
        }
    }
    if (bSpecialSite == false) sRecList += sListEnd;
    return sRecList;
}

function morePrompt(root) {
    var sDocID = root.getAttribute("document_id");
    var sMorePrompt = root.getAttribute("more_prompt");
    return sDocID == '' ? '' : '<div class="recommender_more_link" style="margin: 3px; padding: 0px;" align="center"><a href="' + sShowDocUrl + sDocID + '" style="color:#3987DC !important; text-decoration:none !important; ">' + sMorePrompt + '</a></div>';
}

function createCloseBox(recommendersquat) {
        var close = window.document.createElement("div");
        dom_setStyle(close,
                "margin:3px; position:absolute; top:3px; right:3px; font-family:arial,sans-serif;padding:1px; width:10px; border:1px solid #BBBBBB; text-align:center; cursor:pointer; color:#BBB; font-size:11px; background-color:#fff; font-weight:bold; z-index:999;");
        close.setAttribute("title", "Click to close panel");
        close.addEventListener('click', function() {
            this.parentNode.style.display = "none";
        }, true);
        close.appendChild(window.document.createTextNode("x"));
        recommendersquat.appendChild(close);
}

function verticalScrollBars() {
	var vHeight = 0;
	if (document.all) {
	  if (document.documentElement) {
	    vHeight = document.documentElement.clientHeight;
	  } else {
	    vHeight = document.body.clientHeight
	  }
	} else {
 	 vHeight = window.innerHeight;
	}
	return (document.body.offsetHeight > vHeight);
}

function positionSquatter(recommendersquat, bRealTime) {
    // we treat educommons and mit sites differently
    if (bSpecialSite == true)
    {
        // position the squatter
        recommendersquat.setAttribute("style", 'margin: ' + sTopMargin + ' ' + sRightMargin + ' ' + sBottomMargin + ' ' + sLeftMargin + '; padding: 3px; border:1px solid #000000; background-color:#FFFFFF; z-index:999; font-size: 12px; font-family:Arial, Helvetica, sans-serif !important; ');
    }
    // default positioning and styling
    else {
        // calculate the position for the recommender div
        var squatterWidth = 250;
        var scrollWidth = verticalScrollBars() ? 20 : 5;
        var rightAligned = window.innerWidth - squatterWidth - scrollWidth;

        // position the squatter
	if (bRealTime){
		style = 'margin:0px; border:none; width:' + squatterWidth + 'px; position:absolute; left:' + rightAligned + 'px; top:2px; background-color:transparent; z-index:999;';
	}else{
		style = 'margin:0px; font-size: 12px; font-family:Arial, Helvetica, sans-serif !important; border:1px solid #000; width:' + squatterWidth + 'px; position:absolute; left:' + rightAligned + 'px; top:2px; background-color:#FFF; z-index:999;';
	}
        recommendersquat.setAttribute("style", style);

	recommendersquat.drag = new Drag(document.getElementById('recommendertop'), recommendersquat);
	createCloseBox(recommendersquat);
    }
}

function squatterHeader(sTitle, bFrame) {
 border = bFrame ? "border-top:1px solid black;border-right:1px solid black;border-left:1px solid black;width:240px;" : "border:none;";
 return '<div id="recommendertop" style="text-align:left;color:#777;background-color:white;font-weight:bold;font-size:14px;font-family:Arial,Helvetica,sans-serif;margin: 2px 3px 0 3px; padding: 2px;' + border + '"><img src="' + sBaseUrl + '/images/folksemantic/logo-folksemantic-gm.gif" style="margin-left:2px;vertical-align:middle;"/>&nbsp;&nbsp;' + sTitle + '</div>';
}

function squatterContent(root, recommendations) {
    return squatterHeader(root.getAttribute("title"),false) + recList(recommendations, root.getAttribute("direct_link_text")) + morePrompt(root);
}

function displayGetRecsButton(root,sUrl) {
    setDefaultSquatParent();
    src = sBaseUrl + 'recommendations/get_button?u=' + sUrl;
    header = squatterHeader(root.getAttribute("title"),true);
    displaySquatter(header + '<iframe allowtransparency="true" scrolling="false" width="250px" height="280px" frameborder="0" src="' + src + '"></iframe>', true);
}

function displaySquatter(sContent, bRealTime) {
    var recommendersquat = document.createElement('div');
    recommendersquat.innerHTML = sContent;
    squatParent.insertBefore(recommendersquat, squatSibling);
    positionSquatter(recommendersquat, bRealTime);
}

function getRecs(sUrl) {
    GM_xmlhttpRequest(
    {
        method: 'GET',
        url: sUrl,
        headers: {'User-agent': 'Mozilla/4.0 (compatible) Greasemonkey/0.3'},

        onload: function(responseDetails)
        {
            var dom = new DOMParser().parseFromString(responseDetails.responseText, "application/xml");
            var root = dom.getElementsByTagName('recommendations')[0];
            var recommendations = dom.getElementsByTagName('recommendation');
            if (recommendations.length > 0) {
                displaySquatter(squatterContent(root, recommendations), false);
            } else {
                displayGetRecsButton(root,sUrlToGetRecsFor);
            }
        }
    });
}

var sBaseUrl = '<%= request.protocol + request.host_with_port + '/' %>';
var sServiceUrl = sBaseUrl + 'recommendations.xml?';
var sShowDocUrl = sBaseUrl + 'resources/';
var squatParent = null;
var squatSibling = null;
var sTopMargin = "3px";
var sRightMargin = "3px";
var sBottomMargin = "40px";
var sLeftMargin = "3px";
var bSpecialSite = false;
var bNeeds = false;
var bMIT = false;
var bNeedsRecord = false;
var body = null;
var bodyTags = document.getElementsByTagName('body');
var demoDomains = ['http://ocw.mit.edu','http://www.engineeringpathway.com'];
var blacklistedDomains = [sBaseUrl,'google.com','localhost','folksemantic.com','ocwfinder.org','ocwfinder.com','oerrecommender.org'];
if (sUrlToGetRecsFor.indexOf('http') == 0 && bodyTags && bodyTags.length > 0)
{
    sUrlToGetRecsFor = special_website_url(sUrlToGetRecsFor);
    body = bodyTags[0];
    if ((bNeeds == true && bNeedsRecord == true) || bNeeds == false) {
        identifySquatParent();
    }
    if (squatParent != null) {
        if (!blacklistedDomain(sUrlToGetRecsFor))
            getRecs(sServiceUrl + "u=" + sUrlToGetRecsFor);
    }
}