# Copyright: Copyright 2009 Topic Maps Lab, University of Leipzig.
# License:   Apache License, Version 2.0

module RTM
  def self.from_xtm2lx(*args)
    RTM::IO::FROMXTM2LX.from_xtm2(*args)
  end
end
module RTM::IO
  # XTM2 Export.
  # Each Topic Maps Construct gets a to_xtm2 method.
  # The result is a REXML::Element except for TopicMap where it is a REXML::Document.
  module FROMXTM2LX
    require 'libxml'
    XTM2DEBUG = false
    
    # Reads XTM2 from source (io object).
    # Example: RTM::IO::FROMXTM2.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
      parser = XML::SaxParser.new
      parser.callbacks = XML::LibXMLSax2wrapper.new(FROMXTM2::XTM2Listener.new(base_locator, target || tm, options))
      parser.filename = source
      parser.parse
      #true
    end
  end
end

module XML
  # Acts as Callback structure for the LibXML-Ruby SAX Parser and calls
  # a REXML SAX2Listener API.
  class LibXMLSax2wrapper
    include LibXML::XML::SaxParser::Callbacks
    def initialize(rexml_sax2listener)
      @dest = rexml_sax2listener
      @ns = Hash.new("http://www.topicmaps.org/xtm/")
    end
    def on_start_document
      @dest.start_document
    end
    def on_end_document
      @dest.end_document
    end
    def on_start_element(qname, attr)
      prefix, localname = qname.split(":")
      unless localname
        localname = prefix
        uri = @ns.default
      else
        uri = @ns[prefix]
      end
      @dest.start_element(uri, localname, qname, attr)
    end
    def on_end_element(qname)
      prefix, localname = qname.split(":")
      unless localname
        localname = prefix
        uri = @ns.default
      else
        uri = @ns[prefix]
      end
      @dest.end_element(uri, localname, qname)
    end
    def on_characters(text)
      @dest.characters(text)
    end
    def on_cdata_block(content)
      @dest.cdata(content)
    end
    def on_parser_error(msg)
     warn("SAX Parser Error: #{msg}")
    end
    def on_parser_warning(*msg)
      warn("SAX Parser Warning: #{msg}")
    end
    def on_parser_fatal_error(msg)
      warn("SAX Parser Fatal Error: #{msg}")
    end
  end
end