class Sanitize::Transformers::CleanElement

def call(env)
  name = env[:node_name]
  node = env[:node]
  return if env[:is_whitelisted] || !node.element?
  # Delete any element that isn't in the config whitelist.
  unless @allowed_elements[name]
    # Elements like br, div, p, etc. need to be replaced with whitespace in
    # order to preserve readability.
    if @whitespace_elements[name]
      node.add_previous_sibling(Nokogiri::XML::Text.new(' ', node.document))
      unless node.children.empty?
        node.add_next_sibling(Nokogiri::XML::Text.new(' ', node.document))
      end
    end
    unless @remove_all_contents || @remove_element_contents[name]
      node.children.each {|n| node.add_previous_sibling(n) }
    end
    node.unlink
    return
  end
  attr_whitelist = Set.new((@attributes[name] || []) +
      (@attributes[:all] || []))
  if attr_whitelist.empty?
    # Delete all attributes from elements with no whitelisted attributes.
    node.attribute_nodes.each {|attr| attr.unlink }
  else
    # Delete any attribute that isn't in the whitelist for this element.
    node.attribute_nodes.each do |attr|
      attr.unlink unless attr_whitelist.include?(attr.name.downcase)
    end
    # Delete remaining attributes that use unacceptable protocols.
    if @protocols.has_key?(name)
      protocol = @protocols[name]
      node.attribute_nodes.each do |attr|
        attr_name = attr.name.downcase
        next false unless protocol.has_key?(attr_name)
        del = if attr.value.to_s.downcase =~ REGEX_PROTOCOL
          !protocol[attr_name].include?($1.downcase)
        else
          !protocol[attr_name].include?(:relative)
        end
        attr.unlink if del
      end
    end
  end
  # Add required attributes.
  if @add_attributes.has_key?(name)
    @add_attributes[name].each {|key, val| node[key] = val }
  end
end

def initialize(config)
  @config = config
  # For faster lookups.
  @add_attributes          = config[:add_attributes]
  @allowed_elements        = {}
  @attributes              = config[:attributes]
  @protocols               = config[:protocols]
  @remove_all_contents     = false
  @remove_element_contents = {}
  @whitespace_elements     = {}
  config[:elements].each {|el| @allowed_elements[el] = true }
  config[:whitespace_elements].each {|el| @whitespace_elements[el] = true }
  if config[:remove_contents].is_a?(Array)
    config[:remove_contents].each {|el| @remove_element_contents[el] = true }
  else
    @remove_all_contents = !!config[:remove_contents]
  end
end