//This is the client program.
import java.io*;
import java.net*;

public class Client {
	String SERVER_ADDRESS = "denver.cs.colostate.edu";
	Integer PORT = 5001;

	public static void main(String[] args) throws IOException {
		Socket socketToTheServer;
		DataInputStream inputStream;
		DataOutputStream outputStream; 

		try {
			//We create the socket AND try to connect to the address and port we are running the server on
			socketToTheServer = new Socket(SERVER_ADDRESS, PORT);
			inputStream = new DataInputStream(socketToTheServer.getInputStream());
			outputStream = new DataOutputStream(socketToTheServer.getOutputStream());
		} catch(IOException e) {
			System.out.println("Client::main::creating_the_socket:: " + e);
			System.exit(1);
		}
		// We assume that if we get here we have connected to the server.
		System.out.println("Connected to the server.");

		try {
			Integer msgLength = 0;
			//Try to read an integer from our input stream. This will block if there is nothing.
			msgLength = inputStream.readInt();

			//If we got here that means there was an integer to read and we have the 
			// length of the rest of the next message.
			System.out.println("Received a message length of: " + msgLength);

			//Try to read the incoming message.
			byte[] incomingMessage = new byte[msgLength];
			incomingInputStream.readFully(incomingMessage, 0, msgLength);

			//You could have used .read(byte[] incomingMessage), however this will read 
			// *potentially* incomingMessage.length bytes, maybe less.
			// Whereas .readFully(...) will read exactly msgLength number of bytes. 

			System.out.println("Received Message: " + incomingMessage);

			//Now, let's respond.
			byte[] msgToServer = String("CS455").getBytes();
			Integer msgToServerLength = msgToServer.length;
			//Our self-inflicted protocol says we send the length first
			outputStream.writeInt(msgToServerLength);
			//Then we can send the message
			outputStream.write(msgToServer, 0, msgToServerLength);

			//Close streams and then sockets
			inputStream.close();
			outputStream.close();
			socketToTheServer.close();
		} catch(IOException e) {
			System.out.println("Client::main::talking_to_the_server:: " + e);
			System.exit(1);
		}
	}
}