import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;

/**
 * This obeys the Singleton design pattern.
 * Only one instance of Registry can be generated.
 * It is used by DateServer to keep track of the number of connections made.
 * The synchronization step is from Metsker's Java Workbook book.
 * Most of the code is taken from Java in a Nutshell, 4th ed., pg. 187.
 * Run the DateServer on Denali and then
 * telnet to it via the command below
 *     telnet denali.ccs.neu.edu 8379 
 * The server will then print info to stdout for each telnet connection made.
 * You might want to put in your own port number and recompile this.
 * <br>Singleton Design Pattern example for COM1204 Summer 2003.
 *
 * @author Bob Futrelle
 * @version 0.1, 5 July 2003
 *
 */


public class DateServer {
    public static void main(String[] args) throws java.io.IOException {
	// Get a CharsetEncoder for encoding the text we send to the client
	CharsetEncoder encoder = Charset.forName("US-ASCII").newEncoder();

	// Create a new ServerSocketChannel, and bind it to port 8379.  
	// Note that we have to do this using the underlying ServerSocket.
	ServerSocketChannel server = ServerSocketChannel.open();
	server.socket().bind(new java.net.InetSocketAddress(8379));

	for(;;) {  // This server runs forever
	    // Wait for a client to connect.
	    SocketChannel client = server.accept();  
	    System.out.println("Got a connection");
	    // This returns a singleton, the single instance of Registry
	    Registry registry = Registry.getRegistry();
	    registry.addToCount();
	    registry.report();

	    // Get the current date and time as a string
	    String response = new java.util.Date().toString() + "\r\n";
	    // Wrap, encode, and send the string to the client
	    client.write(encoder.encode(CharBuffer.wrap(response)));
	    // Disconnect from the client
	    client.close();
	}
    }
}