require 'webrick'
require 'drb/drb'
require 'drb/http0'
require 'thread'

module DRb
  module HTTP0

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

    class Callback < WEBrick::HTTPServlet::AbstractServlet
      def initialize(config, drb)
        @config = config
        @drb = drb
        @queue = Queue.new
      end

      def do_POST(req, res)
        @req = req
        @res = res
        @drb.push(self)
        @res.body = @queue.pop
        @res['content-type'] = 'application/octet-stream;'
      end

      def req_body
        @req.body
      end

      def reply(body)
        @queue.push(body)
      end

      def close
        @queue.push('')
      end
    end

    class Server
      def initialize(uri, config)
        @uri = uri
        @config = config
        @queue = Queue.new
        setup_webrick(uri)
      end
      attr_reader :uri

      def close
        @server.shutdown if @server
        @server = nil
      end

      def push(callback)
        @queue.push(callback)
      end

      def accept
        client = @queue.pop
        ServerSide.new(client, @config)
      end

      def setup_webrick(uri)
        logger = WEBrick::Log::new($stderr, WEBrick::Log::FATAL)
        u = URI.parse(uri)
        s = WEBrick::HTTPServer.new(:Port => u.port,
          :AddressFamily => Socket::AF_INET,
          :BindAddress => u.host,
          :Logger => logger,
          :ServerType => Thread)
        s.mount(u.path, Callback, self)
        @server = s
        s.start
      end
    end

    class ServerSide
      def initialize(callback, config)
        @callback = callback
        @config = config
        @msg = DRbMessage.new(@config)
        @req_stream = StrStream.new(@callback.req_body)
      end

      def close
        @callback.close if @callback
        @callback = nil
      end

      def alive?; false; end

      def recv_request
        begin
          @msg.recv_request(@req_stream)
        rescue
          close
          raise $!
        end
      end

      def send_reply(succ, result)
        begin
          return unless @callback
          stream = StrStream.new
          @msg.send_reply(stream, succ, result)
          @callback.reply(stream.buf)
        rescue
          close
          raise $!
        end
      end
    end
  end
end