// ==UserScript==
  // @name           Query Technorati
  // @namespace      http://www.dopiaza.org/flickr/greasemonkey/
  // @description    Query Technorati from Flickr photo pages
  // @include        http://www.flickr.com/photos/*
  // @include        http://flickr.com/photos/*
  // ==/UserScript==
  
  // *** Edit this ***
  // You need to put your Technorati API key here
  var technoratiAPIKey = 'YOUR-TECHNORATI-API-KEY';
      
  var photoPagePattern = /^(.*\/photos\/[\w@-]+\/\d+\/)/;
  
  // Check that we really are on a photo page
  function checkPhotoPage()
  {
    var isPhotoPage = false;
    
    if (photoPagePattern.exec(window.location.href))
    {
      isPhotoPage = true;
    }
  
    return isPhotoPage;
  }
  
  // Normalize the URL, removing any unneeded elements
  function normalizeUrl()
  {
    var url = window.location.href;
    var result = photoPagePattern.exec(url);
    if (result != null)
    {
      url = result[1];
    }
  
    return url;
  }
  
  // Add the "View blogs" link after the privacy element
  function addLink(privacy)
  {
    var parent = privacy.parentNode;
    var blogContainer = document.createElement('p');
    var blogLink = document.createElement('a');
    blogLink.setAttribute('href', '#');
    blogLink.setAttribute('class', 'Plain');
    var text = document.createTextNode('View blogs');
    blogLink.appendChild(text);
    styleElement(blogContainer);
    blogContainer.appendChild(blogLink);
    parent.insertBefore(blogContainer, privacy.nextSibling);
  
    blogLink.addEventListener("click", function(evt)
    {
      var waiting = document.createElement('span');
      waiting.appendChild(document.createTextNode('Waiting for Technorati...'));
      blogContainer.replaceChild(waiting, blogLink);
      showBlogs(blogContainer, waiting);
      evt.preventDefault();
    }, true);
  }
  
  // Retrieve the list of blogs and display them
  function showBlogs(blogContainer, message)
  {
    var url = 'http://api.technorati.com/cosmos';
    var params = 'key=' + technoratiAPIKey + '&url=' + normalizeUrl() + '&limit=100';
  
    GM_xmlhttpRequest(
    {
      method: "GET",
      url: url + "?" + params,
      headers:
      {
         "User-Agent": "Flickr-Technorati-Query"
      },
      onload: function(response) 
      {
        blogContainer.removeChild(message);
        var parser = new unsafeWindow.DOMParser();
        var dom = parser.parseFromString(response.responseText, "application/xml");
  
        var errors = dom.getElementsByTagName('error');
        if (errors.length > 0)
        {
          var p = document.createElement('p');
          p.appendChild(document.createTextNode('Error: ' + errors[0].firstChild.nodeValue));
          styleElement(p);
          blogContainer.appendChild(p);
        }
        else
        {
          var items = dom.getElementsByTagName('item');
          var filteredItems = filterItems(items);
          if (filteredItems.length > 0)
          {
            var list = document.createElement('ul');
            for (var i = 0; i < filteredItems.length; i++)
            {
              addBlog(list, filteredItems[i]);
            }            
            blogContainer.appendChild(list);
          }
          else
          {
            var p = document.createElement('p');
            p.appendChild(document.createTextNode('No blogs found'));
            styleElement(p);
            blogContainer.appendChild(p);
          }
        }
        addTechnoratiCredit(blogContainer);
      },
      onerror: function(response)
      {
        var p = document.createElement('p');
        p.appendChild(document.createTextNode('There was an error retrieving blog information'));
        styleElement(p);
        blogContainer.appendChild(p);
      }
    });
  }
  
  // Filter out the items we want to display
  function filterItems(items)
  {
    var filteredItems = new Array();
  
    for (var i = 0; i < items.length; i++)
    {
      var processed = false;
      var itemName = items[i].getElementsByTagName('name')[0].firstChild.nodeValue;
  
      // Do we have this blog name in the list yet?
      for (var j = 0; j < filteredItems.length; j++)
      {
        var filteredItemName = filteredItems[j].getElementsByTagName('name')[0].firstChild.nodeValue;
        if (itemName == filteredItemName)
        {
          // We have a match. Let's compare the URLs
          var itemUrl = items[i].getElementsByTagName('nearestpermalink')[0].firstChild.nodeValue;
          var filteredItemUrl = filteredItems[j].getElementsByTagName('nearestpermalink')[0].firstChild.nodeValue;
          // We'll assume here that the longest URL is the most specific
          if (itemUrl.length > filteredItemUrl.length)
          {
            // The new item has a longer URL, so replace the old one.
            filteredItems[j] = items[i];
          }
          processed = true;
          break;
        }
      }
  
      if (!processed)
      {
        // We haven't encountered this one before, so append it to the list
        filteredItems.push(items[i]);
      }
    }
    return filteredItems;
  }
  
  // Add this blog to the list
  function addBlog(list, blog)
  {
    var name = blog.getElementsByTagName('name')[0];
    var url = blog.getElementsByTagName('nearestpermalink')[0];
    var excerpt = blog.getElementsByTagName('excerpt')[0];
  
    var li = document.createElement('li');
    li.setAttribute('class', 'Stats');
  
    var a = document.createElement('a');
    a.setAttribute('href', url.firstChild.nodeValue);
    a.setAttribute('class', 'Plain');
    a.appendChild(document.createTextNode(name.firstChild.nodeValue));
    li.appendChild(a);
    li.appendChild(document.createElement('br'));
    li.appendChild(document.createTextNode(excerpt.firstChild.nodeValue));
    list.appendChild(li);
  }
  
  // Add a credit line, linking back to Technorati
  function addTechnoratiCredit(blogContainer)
  {
    var a = document.createElement('a');
    a.setAttribute('href', 'http://www.technorati.com/');
    a.setAttribute('class', 'Plain');
    a.appendChild(document.createTextNode('Technorati'));
  
    var p = document.createElement('p');
    p.appendChild(document.createTextNode('Search results by '));
    p.appendChild(a);
    styleElement(p);
    blogContainer.appendChild(p);
  }
  
  //Style a given node so that it matched the side bar
  function styleElement(node)
  {
    node.style.color = '#999999';
    node.style.fontSize = '11px';
    node.style.lineHeight = '15px';
  }
  
  // The script itself starts here
  if (checkPhotoPage())
  {
    var privacyElements = document.evaluate(
      "//*[@class='Privacy']",
      document,
      null,
      XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
      null);
  
    if (privacyElements.snapshotLength > 0) 
    {
      addLink(privacyElements.snapshotItem(0));
    }
  }