import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

public class KnockServer
{
    // port to bind to
    static int port = 1026;
    static boolean serverRunning = false;

    static String[][] JOKES = 
        { 
            {"Harry", "Harry up and answer this door" },
            {"Heart", "Heart to hear you, speak louder" },
            {"Heaven", "Heaven seen you in ages" },
            {"Costa", "Costa lot" },
            {"Francie", "Francie that" },
            {"Kareem", "Kareem of the crop" },
            {"Ken", "Ken I come in or do I have to climb through a window" },
            {"Lena", "Lena little closer and I'll tell you" },
            {"Tuna", "Tuna piano and it'll sound better" },
        };
    
    // standard program entry point
    public static void main(String args[])
    {
        // The communication attempt must be embedded in a 'try-catch' block
        // to catch the many errors that could occur during communications
        try
        {
            // Starting server by binding to requested port if possible.
            ServerSocket server = new ServerSocket(port);
            System.out.println("Server started: " + server);
            
            // Setting up infinite loop to handle multiple client 
            // connections in sequence. 
            serverRunning = true;
            while (serverRunning)
            {
                // Waiting for incoming connection in a b;ocking call
                Socket socket = server.accept();
                System.out.println("Client Connected: " + socket);
          
                // Handling the client
                try
                {
                    handleClient(socket);
                }
                catch(IOException ioe)
                {
                    System.err.println("Client error: " + ioe.getMessage());
                }
                
                // We are done so we close the client connection. The server
                // itself will remain running, waiting for the next client
                // to connect t the top of the loop.
                System.out.println("Client Disconnected");
                socket.close();
            }
            
            // Closing down the server. At this time this statement is
            // unreachable (which should change in improved versions). 
            server.close();
            System.out.println("Server Disconnected");
        }
        catch (IOException e)
        {
            // Printing error message for all IO exceptions
            e.printStackTrace();
        }
    }

    private static void handleClient(Socket socket) throws IOException
    {
        // setting timeout
        socket.setSoTimeout(10000);
        
        // setting up IO streams
        BufferedReader in = new BufferedReader(
                                new InputStreamReader(
                                    socket.getInputStream()));
        PrintWriter out = new PrintWriter(
                              new OutputStreamWriter(
                                  socket.getOutputStream()));
        System.out.println("IO Streams established");
        
        String version = in.readLine();
        if (version.equals("KK/1.0"))
        {
            println(out, "KK OK:" + JOKES.length);
            String jokeID = in.readLine();
            try
            {
                int id = Integer.parseInt(jokeID);
                if ( (0 <= id) && (id < JOKES.length))
                {
                    println(out, "KK OK");
                    println(out, "KK SETUP:" + JOKES[id][0]);
                    println(out, "KK PUNCH:" + JOKES[id][1]);
                    println(out, "KK BYE");
                }
                else
                    println(out, "KK ERROR 100");
            }
            catch(NumberFormatException nfe)
            {
                println(out, "KK ERROR 200");
            }
        }
        else
            println(out, "KK ERROR 001");
        
        in.close();
        out.close();
    }

    private static void println(PrintWriter out, String string)
    {
        out.println(string);
        out.flush();
    }
}