// ==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));
  }
}