=begin

= File
	metadata.rb

= Info
	This file is part of Origami, PDF manipulation framework for Ruby
	Copyright (C) 2010	Guillaume Delugré <guillaume@security-labs.org>
	All right reserved.
	
  Origami is free software: you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Origami is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with Origami.  If not, see <http://www.gnu.org/licenses/>.

=end

require 'rexml/document'

module Origami

  class PDF

    #
    # Returns true if the document has a document information dictionary.
    #
    def has_document_info?
      has_attr? :Info 
    end

    #
    # Returns true if the document has a catalog metadata stream.
    #
    def has_metadata?
      self.Catalog.Metadata.is_a?(Stream)
    end

    #
    # Returns the document information dictionary if present.
    #
    def get_document_info
      get_doc_attr :Info
    end

    def title; get_document_info_field(:Title) end
    def author; get_document_info_field(:Author) end
    def subject; get_document_info_field(:Subject) end
    def keywords; get_document_info_field(:Keywords) end
    def creator; get_document_info_field(:Creator) end
    def producer; get_document_info_field(:Producer) end
    def creation_date; get_document_info_field(:CreationDate) end
    def mod_date; get_document_info_field(:ModDate) end

    #
    # Returns a Hash of the information found in the metadata stream
    #
    def get_metadata
      metadata_stm = self.Catalog.Metadata

      if metadata_stm.is_a?(Stream)
        doc = REXML::Document.new(metadata_stm.data)

        info = {}

        doc.elements.each('*/*/rdf:Description') do |description|
          
          description.attributes.each_attribute do |attr|
            case attr.prefix
              when 'pdf','xap'
                info[attr.name] = attr.value
            end
          end

          description.elements.each('*') do |element|
            value = (element.elements['.//rdf:li'] || element).text
            info[element.name] = value.to_s
          end

        end

        info
      end
    end

    #
    # Modifies or creates a metadata stream.
    #
    def create_metadata(info = {})
      skeleton = <<-XMP
<?packet begin="#{"\xef\xbb\xbf"}" id="W5M0MpCehiHzreSzNTczkc9d"?>
  <x:xmpmeta xmlns:x="adobe:ns:meta/">
    <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      <rdf:Description rdf:about="" xmlns:pdf="http://ns.adobe.com/pdf/1.3/">
      </rdf:Description>
    </rdf:RDF>
  </x:xmpmeta>
<?xpacket end="w"?>
      XMP

      xml =
        if self.Catalog.Metadata.is_a?(Stream)
          self.Catalog.Metadata.data
        else
          skeleton
        end

      doc = REXML::Document.new(xml)
      desc = doc.elements['*/*/rdf:Description']
  
      info.each do |name, value|
        elt = REXML::Element.new "pdf:#{name}"
        elt.text = value

        desc.elements << elt
      end

      xml = ""; doc.write(xml, 3)

      if self.Catalog.Metadata.is_a?(Stream)
        self.Catalog.Metadata.data = xml
      else
        self.Catalog.Metadata = Stream.new(xml)
      end

      self.Catalog.Metadata
    end

    private

    def get_document_info_field(field) #:nodoc:
      if has_document_info?
        doc_info = get_document_info

        if doc_info.has_key?(field)
          case obj = get_document_info[field].solve
            when String then obj.value
            when Stream then obj.data
          end
        end
      end
    end

  end

  #
  # Class representing an information Dictionary, containing title, author, date of creation and the like.
  #
  class Metadata < Dictionary
    include StandardObject

    field   :Title,                   :Type => String, :Version => "1.1"
    field   :Author,                  :Type => String
    field   :Subject,                 :Type => String, :Version => "1.1"
    field   :Keywords,                :Type => String, :Version => "1.1"
    field   :Creator,                 :Type => String
    field   :Producer,                :Type => String
    field   :CreationDate,            :Type => ByteString
    field   :ModDate,                 :Type => ByteString, :Version => "1.1"
    field   :Trapped,                 :Type => Name, :Default => :Unknown, :Version => "1.3"
  end
  
  #
  # Class representing a metadata Stream.
  # This stream can contain the same information as the Metadata dictionary, but is storing in XML data.
  #
  class MetadataStream < Stream
    include StandardObject
   
    field   :Type,                    :Type => Name, :Default => :Metadata, :Required => true
    field   :Subtype,                 :Type => Name, :Default =>:XML, :Required => true
  end

end
