import drcl.comp.Port;
import drcl.comp.Contract;
import drcl.inet.contract.DatagramContract;

/**
 * Example application class - echoer.
 */
public class echoer extends drcl.net.Module
{
	final static int REQ=1, RPL=2, tos=0;

	static {
		setContract(echoer.class, drcl.net.Module.PortGroup_DOWN + "@", 
                              new DatagramContract(Contract.Role_PEER));
	}

	public echoer()
	{
		super();
	}

	public echoer(String id_)
	{
		super(id_);
	}

	void sendmsg(int type_, double tm_, long dst_, int dport_)
	{
		echopkt pkt_ = new echopkt(type_, tm_);
		downPort.doSending(new DatagramContract.Message(pkt_, 10/*size*/,
                                 drcl.net.Address.NULL_ADDR, dst_, dport_, tos));
	}

	public void send_echo_request(long dst_, int dport_)
	{
		debug("Sending an Echo packet to port " + dport_ + " at node" + dst_);
		sendmsg(REQ, getTime(), dst_, dport_);
	}

	protected void dataArriveAtDownPort(Object data_, Port downPort_)
	{
		if (!(data_ instanceof DatagramContract.Message))
		{
			error(data_, "dataArrivedAtDownPort()", downPort_, "unrecognized data");
			return;
		}
		DatagramContract.Message datagram_ = (DatagramContract.Message) data_;
		long src_ = datagram_.getSource();
		int sport_ = datagram_.getSourcePort();
		echopkt pkt_ = (echopkt)datagram_.getContent();
		if (pkt_.type==RPL)
		{
			double rtt = getTime() - pkt_.time;
			debug("Getting a reply, round-trip time is: " + rtt);
		}
		else {
			debug("Getting a request, sending time is: " + pkt_.time);
			sendmsg(RPL, pkt_.time, src_, sport_);
		}
	}
}