// ==UserScript==
// @name          Jump to Flickr Page Exercise
// @namespace     http://www.dopiaza.org/flickr/greasemonkey/
// @description   Jump to a specific Flickr page in a paginated set of pages.
// @include       http://www.flickr.com/*
// @include       http://flickr.com/*
// ==/UserScript==


var paginators = document.evaluate(
  "//div[@class='Paginator']",
  document,
  null,
  XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
  null);

for (var i = 0; i < paginators.snapshotLength; i++) 
{
  var paginator = paginators.snapshotItem(i);

  // Find the max page number
  var anchors = paginator.getElementsByTagName('A');

  // find the number of the last page linked
  var lastPageNum = 1;
  for (var j = 0; j < anchors.length; j++)
  {
    var children = anchors[j].childNodes;
    if (children.length > 0)
    {
      var child = children[0];
      if (child.nodeType == 3) // Text Node
      {
        var pageVal = child.nodeValue;
        if (!isNaN(pageVal))
        {
          lastPageNum = Math.max(lastPageNum, parseInt(pageVal));
        }
      }
    }             
  }

  // Place the text box immediately before the "next" item, which is the last
  // non-text element in the paginator (There is whitespace after it, which shows
  // up as a text node. It may be an anchor or a span, depending on whether we are 
  // at the last page or not.
  var paginatorChildren = paginator.childNodes;

  var nextElement;
  for (var j = paginatorChildren.length - 1; j >= 0; j--)
  {
    if (paginatorChildren[j].nodeType == 1) // Element Node
    {
      nextElement = paginatorChildren[j];
      break;
    }
  }

  var inputBox = document.createElement('input');
  inputBox.setAttribute("type", "text");
  inputBox.setAttribute("size", "3");

  paginator.insertBefore(inputBox, nextElement);

  inputBox.addEventListener('keypress', function(evt) 
  {
    var keyVal = evt.which;
    var key = String.fromCharCode(keyVal);

    if (key == '\r')
    {
      var pageNum = evt.target.value;
      if (pageNum <= 0 || pageNum > lastPageNum)
      {
        evt.target.value = "";
        evt.preventDefault();
      }
      else
      {
        // So, where are we now?
        var loc = window.location.href;
        // Remove any existing page number
        loc = loc.replace(/page\d+(\/)?$/, '');
        // Append the new page number
        loc += 'page' + pageNum + '/';
        // And go to the new page
        window.location.href = loc;
      }
    }
    else
    {
      if (key != '\b' && isNaN(key))
      {
        evt.preventDefault();
      }
    }
  }, true);
}