package ex9_7;

/**
 * Title:        NameServer class
 * Description:  Server that maintains a list of names which can be looked up
 *
 * Copyright:   (c) 2004, 2005
 * Company:     The Open University
 * @author M257 Course Team
 * @version      1.0
 */

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

public class NameServer
{
    private Map<String,String> nameDatabase;
    private ServerSocket ss;
    private Socket socket;
    
    //Streams for connections
    private InputStream is;
    private OutputStream os;
    private PrintWriter toClient;
    private BufferedReader fromClient;
    
    //use a high numbered non-dedicated port
    private static final int PORT_NUMBER = 3000;
    
    // Protocol definitions
    private static final String CLIENT_QUITTING = "Exit";          // Sent by client
    private static final String USER_NOT_FOUND = "User not known"; // Sent by server
    
    // constructor
    public NameServer()
    {
        System.out.println("...Name Server starting up");
        
        nameDatabase = setUpNameDatabase();
        
        //Establish a Server socket
        try
        {
            ss = new ServerSocket(PORT_NUMBER);
        }
        catch (Exception e)
        {
            System.out.println("Trouble with ServerSocket on port " + PORT_NUMBER +
                    ": " + e);
        }
    } // end constructor
    
    
    //Set up name database and add sample data
    private Map<String, String> setUpNameDatabase()
    {
        Map<String, String> db = new HashMap<String, String>();
        
        db.put("Gareth Williams", "G.R.Williams@java2.co.uk");
        db.put("Robert Thomas", "R.Thomas@java2.co.uk");
        db.put("William Wilson", "W.Wilson@java2.co.uk");
        db.put("Anne Land", "A.Land@java2.co.uk");
        db.put("Dave Phillips", "D.Phillips@java2.co.uk");
        db.put("Kirsten Davis", "K.L.Davis@java2.co.uk");
        System.out.println("...Name database set up");
        
        return db;
    }    
    
    public void run()
    {
        int connectionCount = 0; //Count of client connections
        
        try
        {
            //Loop endlessly waiting for client connections
            while (true)
            {
                // Wait for a connection request
                socket = ss.accept();
                //Client has connected
                connectionCount++;
                System.out.println("...Connection " + connectionCount + " established");
                
                openStreams();
                
                processClientRequests();
                
                closeStreams();
                socket.close();
            }
        }
        catch (Exception e)
        {
            System.out.println("Trouble with a connection " + e);
        }
    }
    
    // set up streams for communicating with the client
    private void openStreams() throws IOException
    {
        final boolean AUTO_FLUSH = true;
        is = socket.getInputStream();
        fromClient = new BufferedReader(new InputStreamReader(is));
        os = socket.getOutputStream();
        toClient = new PrintWriter(os, AUTO_FLUSH);
        System.out.println("...Streams set up");
    }
    
    // process a series of client requests
    // until client terminates the connection
    private void processClientRequests() throws IOException
    {
        String userName; //Name request from client
        String userEmail;
        String reply;    //Reply sent to client
        
        userName = fromClient.readLine(); // get request from client
        while (!(userName.equals(CLIENT_QUITTING)))
        {
            userEmail = nameDatabase.get(userName);
            if (userEmail == null)
            {
                reply = USER_NOT_FOUND;
            }
            else
            {
                reply = userEmail;
            }
            toClient.println(reply);  //Send reply to client
            
            userName = fromClient.readLine(); // get next request
        }
    }
    
    
    private void closeStreams() throws IOException
    {
        toClient.close();
        os.close();
        fromClient.close();
        is.close();
        System.out.println("...Streams closed down");
    }
    
} // end class