Drupal.behaviors.contextReactionBlock = function(context) {
  $('form.context-editor:not(.context-block-processed)')
    .addClass('context-block-processed')
    .each(function() {
      var id = $(this).attr('id');
      Drupal.contextBlockEditor = Drupal.contextBlockEditor || {};
      $(this).bind('init.pageEditor', function(event) {
        Drupal.contextBlockEditor[id] = new DrupalContextBlockEditor($(this));
      });
      $(this).bind('start.pageEditor', function(event, context) {
        // Fallback to first context if param is empty.
        if (!context) {
          context = $(this).data('defaultContext');
        }
        Drupal.contextBlockEditor[id].editStart($(this), context);
      });
      $(this).bind('end.pageEditor', function(event) {
        Drupal.contextBlockEditor[id].editFinish();
      });
    });

  //
  // Admin Form =======================================================
  //
  // ContextBlockForm: Init.
  $('#context-blockform:not(.processed)').each(function() {
    $(this).addClass('processed');
    Drupal.contextBlockForm = new DrupalContextBlockForm($(this));
    Drupal.contextBlockForm.setState();
  });

  // ContextBlockForm: Attach block removal handlers.
  // Lives in behaviors as it may be required for attachment to new DOM elements.
  $('#context-blockform a.remove:not(.processed)').each(function() {
    $(this).addClass('processed');
    $(this).click(function() {
      $(this).parents('tr').eq(0).remove();
      Drupal.contextBlockForm.setState();
      return false;
    });
  });
};

/**
 * Context block form. Default form for editing context block reactions.
 */
DrupalContextBlockForm = function(blockForm) {
  this.state = {};

  this.setState = function() {
    $('table.context-blockform-region', blockForm).each(function() {
      var region = $(this).attr('id').split('context-blockform-region-')[1];
      var blocks = [];
      $('tr', $(this)).each(function() {
        var bid = $(this).attr('id');
        blocks.push(bid);
      });
      Drupal.contextBlockForm.state[region] = blocks;
    });

    // Serialize here and set form element value.
    $('form input.context-blockform-state').val(JSON.stringify(this.state));

    // Hide enabled blocks from selector that are used
    $('table.context-blockform-region tr').each(function() {
      var bid = $(this).attr('id');
      $('div.context-blockform-selector input[value='+bid+']').parents('div.form-item').eq(0).hide();
    });
    // Show blocks in selector that are unused
    $('div.context-blockform-selector input').each(function() {
      var bid = $(this).val();
    });
  };

  // Tabledrag
  // Add additional handlers to update our blocks.
  $.each(Drupal.settings.tableDrag, function(base) {
    var table = $('#' + base + ':not(.processed)', blockForm);
    if (table && table.is('.context-blockform-region')) {
      table.addClass('processed');
      table.bind('mouseup', function(event) {
        Drupal.contextBlockForm.setState();
        return;
      });
    }
  });

  // Add blocks to a region
  $('td.blocks a', blockForm).each(function() {
    $(this).click(function() {
      var region = $(this).attr('href').split('#')[1];
      var selected = $("div.context-blockform-selector input:checked");
      if (selected.size() > 0) {
        selected.each(function() {
          // create new block markup
          var block = document.createElement('tr');
          var text = $(this).parents('div.form-item').eq(0).hide().children('label').text();
          $(block).attr('id', $(this).attr('value')).addClass('draggable');
          $(block).html("<td>"+ text + "<input class='block-weight' /></td><td><a href='' class='remove'>X</a></td>");

          // add block item to region
          var base = "context-blockform-region-"+ region;
          Drupal.tableDrag[base].makeDraggable(block);
          $('table#'+base).append(block);
          Drupal.attachBehaviors($('table#'+base));

          Drupal.contextBlockForm.setState();
          $(this).removeAttr('checked');
        });
      }
      return false;
    });
  });
};

/**
 * Context block editor. AHAH editor for live block reaction editing.
 */
DrupalContextBlockEditor = function(editor) {
  this.editor = editor;
  this.state = {};
  this.blocks = {};
  this.regions = {};

  // Category selector handler.
  // Also set to "Choose a category" option as browsers can retain
  // form values from previous page load.
  $('select.context-block-browser-categories', editor).change(function() {
    var category = $(this).val();
    var params = {
      containment: 'document',
      revert: true,
      dropOnEmpty: true,
      placeholder: 'draggable-placeholder',
      forcePlaceholderSize: true,
      helper: 'clone',
      appendTo: 'body',
      connectWith: ($.ui.version === '1.6') ? ['.ui-sortable'] : '.ui-sortable'
    };
    $('div.category', editor).hide().sortable('destroy');
    $('div.category-'+category, editor).show().sortable(params);
  });
  $('select.context-block-browser-categories', editor).val(0).change();

  return this;
};

DrupalContextBlockEditor.prototype.initBlocks = function(blocks) {
  var self = this;
  this.blocks = blocks;
  blocks.each(function() {
    $(this).addClass('draggable');
    $(this).prepend($('<a class="context-block-handle"></a>'));
    $(this).prepend($('<a class="context-block-remove"></a>').click(function() {
      $(this).parents('div.block').eq(0).fadeOut('medium', function() {
        $(this).remove();
        self.updateBlocks();
      });
      return false;
    }));
  });
};

DrupalContextBlockEditor.prototype.initRegions = function(regions) {
  this.regions = regions;
};

/**
  * Update UI to match the current block states.
  */
DrupalContextBlockEditor.prototype.updateBlocks = function() {
  var browser = $('div.context-block-browser');

  // For all enabled blocks, mark corresponding addables as having been added.
  $('div.block, div.admin-block').each(function() {
    var bid = $(this).attr('id').split('block-')[1]; // Ugh.
    $('#context-block-addable-'+bid, browser).draggable('disable').addClass('context-block-added').removeClass('context-block-addable');
  });
  // For all hidden addables with no corresponding blocks, mark as addable.
  $('.context-block-item', browser).each(function() {
    var bid = $(this).attr('id').split('context-block-addable-')[1];
    if ($('#block-'+bid).size() === 0) {
      $(this).draggable('enable').removeClass('context-block-added').addClass('context-block-addable');
    }
  });

  // Mark empty regions.
  $(this.regions).each(function() {
    if ($('div.block:not(.context-block-hidden):has(a.context-block)', this).size() > 0) {
      $(this).removeClass('context-block-region-empty');
    }
    else {
      $(this).addClass('context-block-region-empty');
    }
  });
};

/**
  * Live update a region.
  */
DrupalContextBlockEditor.prototype.updateRegion = function(event, ui, region, op) {
  switch (op) {
    case 'over':
      $(region).removeClass('context-block-region-empty');
      break;
    case 'out':
      if (
        $('div.block:not(.context-block-hidden):has(a.context-block)', region).size() == 0 || 
        ($('div.block:not(.context-block-hidden):has(a.context-block)', region).size() == 1 &&
        $('div.block:not(.context-block-hidden):has(a.context-block)', region).attr('id') == ui.item.attr('id'))
      ) {
        $(region).addClass('context-block-region-empty');
      }
      break;
  }
};

/**
  * Remove script elements while dragging & dropping.
  */
DrupalContextBlockEditor.prototype.scriptFix = function(event, ui, editor, context) {
  if ($('script', ui.item)) {
    var placeholder = $(Drupal.settings.contextBlockEditor.scriptPlaceholder);
    var label = $('div.handle label', ui.item).text();
    placeholder.children('strong').html(label);
    $('script', ui.item).parent().empty().append(placeholder);
  }
};

/**
  * Add a block to a region through an AHAH load of the block contents.
  */
DrupalContextBlockEditor.prototype.addBlock = function(event, ui, editor, context) {
  var self = this;
  if (ui.item.is('.context-block-addable')) {
    var bid = ui.item.attr('id').split('context-block-addable-')[1];

    // Construct query params for our AJAX block request.
    var params = Drupal.settings.contextBlockEditor.params;
    params.context_block = bid + ',' + context;

    // Replace item with loading block.
    var blockLoading = $('<div class="context-block-item context-block-loading"><span class="icon"></span></div>');
    ui.item.addClass('context-block-added');
    ui.item.after(blockLoading);
    ui.sender.append(ui.item);

    $.getJSON(Drupal.settings.contextBlockEditor.path, params, function(data) {
      if (data.status) {
        var newBlock = $(data.block);
        if ($('script', newBlock)) {
          $('script', newBlock).remove();
        }
        blockLoading.fadeOut(function() {
          $(this).replaceWith(newBlock);
          self.initBlocks(newBlock);
          self.updateBlocks();
          $.each(data.css, function(k, v){
            var cssfile = Drupal.settings.basePath + v;
            if ($('head link[href $='+cssfile+']').length === 0 ) {
              $('head').append('<link type="text/css" rel="stylesheet" media="all" href="' + cssfile + " />'");
            }
          });
          Drupal.attachBehaviors();
        });
      }
      else {
        blockLoading.fadeOut(function() { $(this).remove(); });
      }
    });
  }
  else if (ui.item.is(':has(a.context-block)')) {
    self.updateBlocks();
  }
};

/**
  * Update form hidden field with JSON representation of current block visibility states.
  */
DrupalContextBlockEditor.prototype.setState = function() {
  var self = this;

  $(this.regions).each(function() {
    var region = $('a.context-block-region', this).attr('id').split('context-block-region-')[1];
    var blocks = [];
    $('a.context-block', $(this)).each(function() {
      if ($(this).attr('class').indexOf('edit-') != -1) {
        var bid = $(this).attr('id').split('context-block-')[1];
        var context = $(this).attr('class').split('edit-')[1].split(' ')[0];
        context = context ? context : 0;
        var block = {'bid': bid, 'context': context};
        blocks.push(block);
      }
    });
    self.state[region] = blocks;
  });

  // Serialize here and set form element value.
  $('input.context-block-editor-state', this.editor).val(JSON.stringify(this.state));
};

/**
  * Disable text selection.
  */
DrupalContextBlockEditor.prototype.disableTextSelect = function() {
  if ($.browser.safari) {
    $('div.block:has(a.context-block):not(:has(input,textarea))').css('WebkitUserSelect','none');
  }
  else if ($.browser.mozilla) {
    $('div.block:has(a.context-block):not(:has(input,textarea))').css('MozUserSelect','none');
  }
  else if ($.browser.msie) {
    $('div.block:has(a.context-block):not(:has(input,textarea))').bind('selectstart.contextBlockEditor', function() { return false; });
  }
  else {
    $(this).bind('mousedown.contextBlockEditor', function() { return false; });
  }
};

/**
  * Enable text selection.
  */
DrupalContextBlockEditor.prototype.enableTextSelect = function() {
  if ($.browser.safari) {
    $('*').css('WebkitUserSelect','');
  }
  else if ($.browser.mozilla) {
    $('*').css('MozUserSelect','');
  }
  else if ($.browser.msie) {
    $('*').unbind('selectstart.contextBlockEditor');
  }
  else {
    $(this).unbind('mousedown.contextBlockEditor');
  }
};

/**
  * Start editing. Attach handlers, begin draggable/sortables.
  */
DrupalContextBlockEditor.prototype.editStart = function(editor, context) {
  var self = this;

  // This is redundant to the start handler found in context_ui.js.
  // However it's necessary that we trigger this class addition before
  // we call .sortable() as the empty regions need to be visible.
  $(document.body).addClass('context-editing');
  this.editor.addClass('context-editing');

  this.disableTextSelect();
  this.initBlocks($('div.block:has(a.context-block.edit-'+context+')'));
  this.initRegions($('a.context-block-region').parent());
  this.updateBlocks();

  // First pass, enable sortables on all regions.
  $(this.regions).each(function() {
    var region = $(this);
    var params = {
      containment: 'document',
      revert: true,
      dropOnEmpty: true,
      placeholder: 'draggable-placeholder',
      forcePlaceholderSize: true,
      items: '> div.block:has(a.context-block.editable)',
      handle: 'a.context-block-handle',
      start: function(event, ui) { self.scriptFix(event, ui, editor, context); },
      stop: function(event, ui) { self.addBlock(event, ui, editor, context); },
      receive: function(event, ui) { self.addBlock(event, ui, editor, context); },
      over: function(event, ui) { self.updateRegion(event, ui, region, 'over'); },
      out: function(event, ui) { self.updateRegion(event, ui, region, 'out'); }
    };
    region.sortable(params);
  });

  // Second pass, hook up all regions via connectWith to each other.
  $(this.regions).each(function() {
    $(this).sortable('option', 'connectWith', ['.ui-sortable']);
  });

  // Terrible, terrible workaround for parentoffset issue in Safari.
  // The proper fix for this issue has been committed to jQuery UI, but was
  // not included in the 1.6 release. Therefore, we do a browser agent hack
  // to ensure that Safari users are covered by the offset fix found here:
  // http://dev.jqueryui.com/changeset/2073.
  if ($.ui.version === '1.6' && $.browser.safari) {
    $.browser.mozilla = true;
  }
};

/**
  * Finish editing. Remove handlers.
  */
DrupalContextBlockEditor.prototype.editFinish = function() {
  this.editor.removeClass('context-editing');
  this.enableTextSelect();

  // Remove UI elements.
  $(this.blocks).each(function() {
    $('a.context-block-handle, a.context-block-remove', this).remove();
    $(this).removeClass('draggable');
  });
  this.regions.sortable('destroy');

  this.setState();

  // Unhack the user agent.
  if ($.ui.version === '1.6' && $.browser.safari) {
    $.browser.mozilla = false;
  }
};
      if ($('table.context-blockform-region tr#'+bid).size() === 0) {
        $(this).parents('div.form-item').eq(0).show();
      }