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

class SmtpServer2 {
	static Vector<String> cmd = new Vector<String>();

	static int whichCommand(String s) {
	if (cmd.size()==0) {cmd.add("HELO"); cmd.add("EHLO"); cmd.add("MAIL"); cmd.add("RCPT"); cmd.add("DATA"); cmd.add("."); cmd.add("QUIT"); }
	return cmd.indexOf(s);
	}

	public static void main(String args[]) throws IOException{
		ServerSocket ss = new ServerSocket(25000);
		do {
			Socket s = ss.accept();
			PrintWriter fos = new PrintWriter(new FileOutputStream("received.txt"),true);
			PrintWriter sout = new PrintWriter(s.getOutputStream(),true);
			Scanner sin = new Scanner(s.getInputStream());
			// first greet the client
			System.out.println("NEW CLIENT");
			sout.println("220 localhost tiny SMTP server\r");
			boolean done=false;
			int state=0;
			while(!done) {
				String command = sin.nextLine();
				String[] tokens = command.split(" ");
				int cmd = whichCommand(tokens[0]);
				switch(state) {
					case 0: if(cmd==0 || cmd==1) {sout.println("250 Hello "+tokens[1]); state=1; } else done=true; 	break;
					case 1: if(cmd==2) {sout.println("250 Sender ok "); state=2; } else done=true;       break;
					case 2: if(cmd==3) {sout.println("250 Receiver ok "); state=3; } else done=true;   	break;
					case 3: if(cmd==4) {sout.println("354 data reception "); state=4; } else done=true;     	break;
					case 4: if(cmd==5) {sout.println("250 Message accepted for delivery\r"); state=5;}
							else fos.println(command); 	break;
					case 5: if(cmd==6) sout.println("221 Closing connection\r"); done=true;	break;
				}
			}
			System.out.println("CLIENT GONE");
			fos.close(); sin.close(); s.close();
		}while(true); // it's a server, endless loop !!!
	}
}