var SocialHistory = function( moreSites ){

  var sites = {
    "Digg": ["http://digg.com", "http://digg.com/login"],
    "Reddit": ["http://reddit.com/r/NSFW_nospam/", "http://reddit.com/r/nsfw/"],
    "StumbleUpon": ["http://stumbleupon.com"],
    "Del.icio.us": ["https://secure.del.icio.us/login", "http://del.icio.us/"],
    "Google Bookmarks": ["http://www.google.com/bookmarks", "http://www.google.com/ig/add?moduleurl=bookmarks.xml&hl=en"]
  };
  
  for( var site in moreSites ) {
    if( typeof( sites[site] ) == "undefined" ) sites[site] = [];
    if( typeof( moreSites[site] ) == "string" )
      sites[site].push( moreSites[site] );
    else
      sites[site] = sites[site].concat( moreSites[site] );
  }
  
  var visited = {};

  function getStyle(el, scopeDoc,styleProp) {
    if (el.currentStyle)
      var y = el.currentStyle[styleProp];
    else if (window.getComputedStyle)
      var y = scopeDoc.defaultView.getComputedStyle(el,null).getPropertyValue(styleProp);
    return y;
  }
  
  function remove( el ) {
    el.parentNode.removeChild( el );
  }
  
  function createIframe() {
    var iframe = document.createElement("iframe");
    iframe.style.position = "absolute";
    iframe.style.visibility = "hidden";

    document.body.appendChild(iframe);

    if(iframe.contentDocument) iframe.doc = iframe.contentDocument;
    else if(iframe.contentWindow) iframe.doc = iframe.contentWindow.document;

    iframe.doc.open();
  	iframe.doc.write('<style>');
  	iframe.doc.write("a{color: #000000; display:none;}");  	
  	iframe.doc.write("a:visited {color: #FF0000; display:inline;}");  	
  	iframe.doc.write('</style>');
    iframe.doc.close();
    
    return iframe;
  }  

  var iframe = createIframe();
  
  function embedLinkInIframe( href, text ) {
    var a = iframe.doc.createElement("a");
    a.href = href;
    a.innerHTML = site;
    iframe.doc.body.appendChild( a );
  }
  
  for( var site in sites ) {
    var urls = sites[site];
    for( var i=0; i<urls.length; i++ ) {
      embedLinkInIframe( urls[i], site );
      
      if( urls[i].match(/www\./) ){
        var sansWWW = urls[i].replace(/www\./, "");
        embedLinkInIframe( sansWWW, site );
      } else {
        var httpLen = urls[i].indexOf("//") + 2;
        var withWWW = urls[i].substring(0, httpLen ) + "www." + urls[i].substring( httpLen );
        embedLinkInIframe( withWWW, site );
      }
      
    }
  }
    
  var links = iframe.doc.body.childNodes;
  for( var i=0; i<links.length; i++) {
    var displayValue = getStyle(links[i], iframe.doc, "display");
    var didVisit = displayValue != "none";
      
    if( didVisit ){
      visited[ links[i].innerHTML ] = true;
    }
  }
  
  remove( iframe );
  
  return new (function(){
    var usedSites = [];
    for( var site in visited ){
      usedSites.push( site );
    }
    
    this.visitedSites = function() {
      return usedSites;
    }
    
    this.doesVisit = function( site ) {
      if( typeof( sites[site] ) == "undefined" )
        return -1;
      return typeof( visited[site] ) != "undefined";
    }
    
    var checkedSites = [];
    for( var site in sites ){
      checkedSites.push( site );
    }
    this.checkedSites = function(){
      return checkedSites;
    }
  })();
}