#require 'rexml/document'
#require 'rexml/streamlistener'

# Plist parses Mac OS X xml property list files into ruby data structures.
#
# Note: Date and Data elements are not yet implemented.  Plist::parse_xml
# should blow up if when it encounters such elements.  If you encounter
# such an error, please send your plist file to patrick@hexane.org,
# so that I can implement the proper support.
#
# The main point of this api is one method: Plist::parse_xml( filename )
class Plist
  
  def Plist::parse_xml( filename )
    listener = Listener.new
    #parser = REXML::Parsers::StreamParser.new(File.new(filename), listener)
    parser = StreamParser.new(filename, listener)
    parser.parse
    listener.result
  end

  class Listener
    attr_accessor :result, :open

    def initialize
      @result = nil
      @open   = Array.new
    end

    #include REXML::StreamListener
    
    def tag_start(name, attributes)
      @open.push PTag::mappings[name].new
    end
   
    def text( contents )
      @open.last.text = contents if @open.last
    end

    def tag_end(name)
      last = @open.pop
      if @open.empty?
        @result = last.to_ruby
      else
        @open.last.children.push last
      end
    end
  end

  class StreamParser
    def initialize( filename, listener )
      @filename = filename
      @listener = listener
    end
    
    TEXT       = /([^<]+)/
    XMLDECL_PATTERN = /<\?xml\s+(.*?)\?>*/um
    DOCTYPE_PATTERN = /\s*<!DOCTYPE\s+(.*?)(\[|>)/um
      

    def parse
      plist_tags = PTag::mappings.keys.join('|')
      start_tag  = /<(#{plist_tags})([^>]*)>/i
      end_tag    = /<\/(#{plist_tags})[^>]*>/i
    
      require 'strscan'
      @scanner = StringScanner.new( File.open(@filename, "r") {|f| f.read} )
      until @scanner.eos?
        if @scanner.scan(XMLDECL_PATTERN)
        elsif @scanner.scan(DOCTYPE_PATTERN)
        elsif @scanner.scan(start_tag)
          @listener.tag_start(@scanner[1], nil)
          if (@scanner[2] =~ /\/$/)
            @listener.tag_end(@scanner[1])
          end
        elsif @scanner.scan(TEXT)
          @listener.text(@scanner[1]) 
        elsif @scanner.scan(end_tag)
          @listener.tag_end(@scanner[1])
        else
          raise "Unimplemented element"
        end
      end
    end
  end

  class PTag
    @@mappings = { }
    def PTag::mappings
      @@mappings
    end

    def PTag::inherited( sub_class )
      key = sub_class.to_s.downcase
      key.gsub!(/^plist::/, '' )
      key.gsub!(/^p/, '')  unless key == "plist"

      @@mappings[key] = sub_class
    end

    attr_accessor :text, :children
    def initialize
      @children = Array.new
    end

    def to_ruby
      raise "Unimplemented: " + self.class.to_s + "#to_ruby on #{self.inspect}"
    end
  end

  class PList < PTag
    def to_ruby
      children.first.to_ruby
    end
  end

  class PDict < PTag
    def to_ruby
      dict = Hash.new
      key = nil
      
      children.each do |c|
        if key.nil?
          key = c.to_ruby
        else
          dict[key] = c.to_ruby
          key = nil
        end
      end

      dict
    end
  end
  
  class PKey < PTag
    def to_ruby
      text
    end
  end
 
  class PString < PTag
    def to_ruby
      text
    end
  end

  class PArray < PTag
    def to_ruby
      children.collect do |c|
        c.to_ruby
      end
    end
  end

  class PInteger < PTag
    def to_ruby
      text.to_i
    end
  end

  class PTrue < PTag
    def to_ruby
      true
    end
  end

  class PFalse < PTag
    def to_ruby
      false
    end
  end

  class PReal < PTag
    def to_ruby
      text.to_f
    end
  end
end