protocol-machine-01.coffee

class Protocol
	constructor: ->
		@recvCbs = []
		@recvBuffer = new ByteBuffer
		@socket = new Socket
		@socket.onData = @onData.bind(this)
	
	send: (buf) -> @socket.write(buf)
	recv: (n, cb) -> @recvCbs.push({n: n, cb: cb})

	onException: (msg) ->
		console.error "protocol exception: #{msg}"
		delete @recvBuffer, @recvCbs
		@socket.close()

	onData: (data) ->
		@recvBuffer.pushBuf data
		while @recvCbs[0] && @recvBuffer.length() >= @recvCbs[0].n
			cb = @recvCbs.shift()
			buf = @recvBuffer.splice(0, cb.n)
			cb.cb(buf)
			break if not @recvBuffer # exception during handling; break out

	pingPong: ->
		packet = new ByteBuffer
		packet.pushString "PING"
		@send packet

		@recv 4, (packet) =>
			string = packet.grabString()
			return @onException("unexpected packet") if string != "PONG"
			console.log "received pong"