require 'drb/drb'
require 'net/http'
require 'uri'

module DRb
  module HTTP0
    class StrStream
      def initialize(str='')
        @buf = str
      end
      attr_reader :buf

      def read(n)
        begin
          return @buf[0,n]
        ensure
          @buf[0,n] = ''
        end
      end

      def write(s)
        @buf.concat s
      end
    end

    def self.uri_option(uri, config)
      return uri, nil
    end

    def self.open(uri, config)
      unless /^http:/ =~ uri
        raise(DRbBadScheme, uri) unless uri =~ /^http:/
        raise(DRbBadURI, 'can\'t parse uri:' + uri)
      end
      ClientSide.new(uri, config)
    end

    class ClientSide
      def initialize(uri, config)
        @uri = uri
        @res = nil
        @config = config
        @msg = DRbMessage.new(config)
        @proxy = ENV['HTTP_PROXY']
      end

      def close; end
      def alive?; false; end

      def send_request(ref, msg_id, *arg, &b)
        stream = StrStream.new
        @msg.send_request(stream, ref, msg_id, *arg, &b)
        @reply_stream = StrStream.new
        post(@uri, stream.buf)
      end

      def recv_reply
        @msg.recv_reply(@reply_stream)
      end

      def post(url, data)
        it = URI.parse(url)
        path = [(it.path=='' ? '/' : it.path), it.query].compact.join('?')
        http = Net::HTTP.new(it.host, it.port)
        sio = StrStream.new
        http.post(path, data, {'Content-Type'=>'application/octetstream;'}) do |str|
          sio.write(str)
          if @config[:load_limit] < sio.buf.size
            raise TypeError, 'too large packet'
          end
        end
        @reply_stream = sio
      end
    end
  end
  DRbProtocol.add_protocol(HTTP0)
end