module ActiveFedora::Datastreams::NokogiriDatastreams

def autocreate?
  changed_attributes.has_key? :profile
end

def content
  @content = to_xml if ng_xml_changed? || autocreate?
  super
end

def content=(new_content)
  if remote_content != new_content.to_s
    ng_xml_will_change!
    @ng_xml = Nokogiri::XML::Document.parse(new_content)
    super(@ng_xml.to_s.strip)
  end
  self.class.decorate_ng_xml @ng_xml
end

def content_changed?
  return true if autocreate? && new_record?
  return false unless xml_loaded
  ng_xml_changed?
end

def ng_xml 
  @ng_xml ||= begin
    if new_record?
      ## Load up the template
      xml = self.class.xml_template
    else
      xml = Nokogiri::XML::Document.parse(remote_content)
    end
    self.class.decorate_ng_xml xml
  end
end

def ng_xml=(new_xml)
  # before we set ng_xml, we load the datastream so we know if the new value differs.
  # TODO reinstate this
  #local_or_remote_content(true)
  case new_xml 
  when Nokogiri::XML::Document
    self.content=new_xml.to_xml
  when  Nokogiri::XML::Node 
    ## Cast a fragment to a document
    self.content=new_xml.to_s
  when String 
    self.content=new_xml
  else
    raise TypeError, "You passed a #{new_xml.class} into the ng_xml of the #{self.dsid} datastream. OmDatastream.ng_xml= only accepts Nokogiri::XML::Document, Nokogiri::XML::Element, Nokogiri::XML::Node, or raw XML (String) as inputs."
  end
end

def ng_xml_changed?
  changed_attributes.has_key? 'ng_xml'
end

def ng_xml_doesnt_change!
  changed_attributes.delete('ng_xml')
end

def ng_xml_will_change!
  changed_attributes['ng_xml'] = nil
end

def refresh_attributes
  changed_attributes.clear
  @ng_xml = nil
end

def remote_content
  @datastream_content ||= Nokogiri::XML(super).to_xml {|config| config.no_declaration}.strip
end

def to_xml(xml = nil)
  xml = self.ng_xml if xml.nil?
  ng_xml = self.ng_xml
  if ng_xml.respond_to?(:root) && ng_xml.root.nil? && self.class.respond_to?(:root_property_ref) && !self.class.root_property_ref.nil?
    ng_xml = self.class.generate(self.class.root_property_ref, "")
    if xml.root.nil?
      xml = ng_xml
    end
  end
  unless xml == ng_xml || ng_xml.root.nil?
    if xml.kind_of?(Nokogiri::XML::Document)
        xml.root.add_child(ng_xml.root)
    elsif xml.kind_of?(Nokogiri::XML::Node)
        xml.add_child(ng_xml.root)
    else
        raise "You can only pass instances of Nokogiri::XML::Node into this method.  You passed in #{xml}"
    end
  end
  return xml.to_xml.strip
end

def xml_loaded
  instance_variable_defined? :@ng_xml
end