require 'java'
include_class %w[SAXParser SAXParserFactory].map{|i| "javax.xml.parsers.#{i}"}

module RTM::IO
  # XTM2 Import using JAXP

  module FROMXTM2JAXP
    XTM2DEBUG = false
    # Reads XTM2 from source (io object).
    # Example: RTM::IO::FROMXTM2JAXP.from_xtm2(File.open(file_name),"http://rtm.rubyforge.org/topicmaps/tm1/")
    # supported options:
    # :strip_whitespace (defaults to false, may be set to true),
    # :deprefix (defaults to nil, may be set to a string (or regex) which will be removed from the beginning of an (unresolved) item_identifier if it is there.
    def self.from_xtm2(source, base_locator, target=nil,options={})
      tm = RTM.create(base_locator) unless target
      factory = javax.xml.parsers.SAXParserFactory.newInstance()
      # Specifies that the parser produced by this code will provide support for XML namespaces.
      factory.setNamespaceAware(true);
      # Specifies that the parser produced by this code will validate documents as they are parsed.
      factory.setValidating(true);
      parser = factory.newSAXParser();
      internal_handler = FROMXTM2::XTM2Listener.new(base_locator, target || tm, options)
      #internal_handler = EmptyHandler.new
      handler = XML::JAXPSax2wrapper.new(internal_handler)
      parser.parse(source, handler)
      #true
    end
  end
  class EmptyHandler
    def start_document(*args)
    end
    def end_document(*args)
    end
    def start_element(*args)
      puts "start_element: #{args.inspect}"
    end
    def end_element(*args)
      puts "end_element: #{args.inspect}"
    end
    def characters(*args)
      puts "characters: #{args.inspect}"
    end
  end
end

module XML
  # Acts as Callback structure for the JAXP SAX Parser and calls
  # a REXML SAX2Listener API.
  include_class "org.xml.sax.helpers.DefaultHandler"
  class JAXPSax2wrapper < DefaultHandler
    def initialize(rexml_sax2listener)
      super()
      @dest = rexml_sax2listener
    end
    def startDocument
      @dest.start_document
    end
    def endDocument
      @dest.end_document
    end
    def startElement(namespaceURI, localName, qName, attr)
      # copy attributes into hash - this is NOT namespace aware!
      # comments for implementing namespace-awareness:
      #   if qname==localname, namespace uri seems to be == ""
      #   if uri is "" it should be expanded to the default ns which might be http://www.topicmaps.org/xtm/ if we are "main"
      # the following just takes all attributes and passes them on, with their qnames,
      # so it possibly won't work if attributes we need have a namespace declared, even if it is correct.
      attr2 = {}
      attr.length.times {|i| attr2[attr.qname(i)] = attr.value(i)}
      @dest.start_element(namespaceURI, localName, qName, attr2)
    end

    def characters(ch, start, length)
      s = java.lang.String.new(ch,start,length).to_s # hard work to get a ruby string out of a java char[]
      s.strip!
      return if s.size == 0 # we suppress whitespace-only characters. it's not 100% correct but...
      @dest.characters(s)
    end

    def endElement(namespaceURI, localName, qName)
#      puts "endElement: #{namespaceURI.inspect} #{localName.inspect} #{qName.inspect}"
      @dest.end_element(namespaceURI, localName, qName)
    end
  end
end