import java.util.*;
import java.net.*;
import java.io.*;

// This is a simple registry server.
// The system does not do any error checking or bound checking.
// It uses the ROR as specified in the coursework sheet.

// protocol: 
//   (1) lookup  --> returns ROR.
//   (2) rebind --> binds ROR.
//   (3) whoareyou --> I am simple registry etc.
// it is used through SimpleRegistry and LocateSimpleRegistry.

public class SimpleRegistryServer {

    public static void main(String args[])    
	throws IOException
    {
	// I do no checking. A user supplies one argument,
	// which is a port name for the registry 
	// at the host in which it is running.
	int port = Integer.parseInt(args[0]);
	
	// create a socket.
	ServerSocket serverSoc = new ServerSocket(port);
	System.out.println("server socket created.\n");

	// create a table of keys (service names) and ROR.
	Hashtable table = new Hashtable();
	
	// loop: accept, receive request, reply, close.
	// again no error checking: this is not robust at all.
	// it does not reuse connection.
	// moreover there is no concurrency: this is a bad 
        // server programming. 
	// in any way.

	while (true)
	    {
		// create new connections.
		Socket newsoc = serverSoc.accept();

		System.out.println("accepted the request.");
		
		// input/output streams (remember, TCP is bidirectional).
		BufferedReader in = 
		    new BufferedReader(new InputStreamReader (newsoc.getInputStream()));
		PrintWriter out = 
		    new PrintWriter(newsoc.getOutputStream(), true);

		// get a line. this should be a command:
		// (1) lookup  servicename --> ["found", ROR data] or ["not found"]
		// (2) rebound servicename ROR --> ["bound"] 
		// (3) who are you? --> I am a simple registry.

		String command = in.readLine();
		// branch: commands are either lookup or rebind.
		if (command.equals("lookup"))
		    {
			System.out.println("it is lookup request.");

			String serviceName = in.readLine();

			System.out.println("The service name is "+serviceName+".");
			
			// tests if it is in the table.
			// if it is gets it.
			if (table.containsKey(serviceName))
			    {
				System.out.println("the service found.");

				RemoteObjectRef ror=
				    (RemoteObjectRef) table.get(serviceName);
 
				System.out.println
				    ("ROR is "+
				     ror.IP_adr+","+
				     ror.Port+","+
				     ror.Obj_Key+","+
				     ror.Remote_Interface_Name+".");

				out.println("found");
				out.println(ror.IP_adr);
				out.println(Integer.toString(ror.Port));
				out.println(Integer.toString(ror.Obj_Key));
				out.println(ror.Remote_Interface_Name);

				System.out.println("ROR was sent.\n");
			    }
			else
			    {
				System.out.println("the service not found.\n");

				out.println("not found");
			    }
		    }
		else if (command.equals("rebind"))
		    {
			System.out.println("it is rebind request.");

			// again no error check.
			String serviceName = in.readLine();

			System.out.println("the service name is "+serviceName+".");
			
			// get ROR data.
			// I do not serialise. 
			// Go elementary, that is my slogan.

			System.out.println("I got the following ror:");

			String IP_adr = 
			    in.readLine();
			int Port = 
			    Integer.parseInt(in.readLine());
			int Obj_Key = 
			    Integer.parseInt(in.readLine());
			String Remote_Interface_Name = 
			    in.readLine();

			System.out.println("IP address: "+IP_adr);
			System.out.println("port num:"+Port);
			System.out.println("object key:"+Obj_Key);
			System.out.println("Interface Name:"+Remote_Interface_Name);
			
			// make ROR.
			RemoteObjectRef ror=
			    new RemoteObjectRef(IP_adr, 
						Port,
						Obj_Key,
						Remote_Interface_Name);

			// put it in the table.
			table.remove(serviceName);
			Object res = table.put(serviceName, ror);

			System.out.println("ROR is put in the table.\n");
				
			// ack.
			out.println("bound");
		    }
		else if (command.equals("who are you?"))
		    {
			out.println("I am a simple registry.");
			System.out.println("I was asked who I am, so I answered.\n");
		    }
		else
		    {
			System.out.println("I got an imcomprehensive message.\n");
		    }

		// close the socket.
		newsoc.close();
	    }
    }
}