/*************************************
 * Filename:  SMTPConnect.java
 * Names: Thomas Patterson
 * Student-IDs: 201263503
 * Date: 12/10/2018
 *************************************/
import java.net.*;
import java.io.*;
import java.security.cert.CRL;
import java.util.*;

/**
 * Open an SMTP connection to mailserver and send one mail.
 *
 */
public class SMTPConnect {
    /* The socket to the server */
    private Socket connection;

    /* Streams for reading from and writing to socket */
    private BufferedReader fromServer;
    private DataOutputStream toServer;

    private static final String CRLF = "\r\n";

    /* Are we connected? Used in close() to determine what to do. */
    private boolean isConnected = false;

    /* Create an SMTPConnect object. Create the socket and the
       associated streams. Initialise SMTP connection. */
    public SMTPConnect(EmailMessage mailmessage) throws IOException {
        // Open a TCP client socket with hostname and portnumber specified in
        // mailmessage.DestHost and  mailmessage.DestHostPort, respectively.
	connection = new Socket(mailmessage.DestHost, mailmessage.DestHostPort);

        // attach the BufferedReader fromServer to read from the socket and
        // the DataOutputStream toServer to write to the socket
        fromServer = new BufferedReader(new InputStreamReader(connection.getInputStream()));
	toServer =   new DataOutputStream(connection.getOutputStream);

	/* Fill in */
        String response = fromServer.readLine();
        System.out.println(response);
        if (!response.startsWith("220")) {
            throw new Exception("220 reply not received from server.");
        }
	/* Read one line from server and check that the reply code is 220.
	   If not, throw an IOException. */
	/* Fill in */

	/* SMTP handshake. We need the name of the local machine.
	   Send the appropriate SMTP handshake command. */
	String localhost = InetAddress.getLocalHost().getHostName();
	sendCommand("HELO"+ localhost + CRLF + 250);
	isConnected = true;
    }

    /* Send message. Write the correct SMTP-commands in the
       correct order. No checking for errors, just throw them to the
       caller. */
    public void send(EmailMessage mailmessage) throws IOException {
	/* Fill in */
	/* Send all the necessary commands to send a message. Call
	   sendCommand() to do the dirty work. Do _not_ catch the
	   exception thrown from sendCommand(). */
        sendCommand("MAIL FROM: "+mailmessage.Sender+CRLF, 250);
        sendCommand("RCPT TO: " + mailmessage.Recipient+CRLF, 250);
        sendCommand("DATA" +mailmessage.Headers + CRLF + mailmessage.Body +CRLF + "." + CRLF, 354);

	/* Fill in */
    }

    /* Close SMTP connection. First, terminate on SMTP level, then
       close the socket. */
    public void close() {
	isConnected = false;
	try {
	    sendCommand("QUIT" + CRLF, 221);
	    connection.close();
	} catch (IOException e) {
	    System.out.println("Unable to close connection: " + e);
	    isConnected = true;
	}
    }

    /* Send an SMTP command to the server. Check that the reply code is
       what is is supposed to be according to RFC 821. */
    private void sendCommand(String command, int rc) throws IOException {
	/* Fill in */
        System.out.print(command);
        toServer.writeBytes(command);
        String response = fromServer.readline();
        System.out.println(response);

	/* Fill in */

	/* Fill in */
        if (!response.startsWith(Integer.toString(rc))) {
            throw new Exception(rc + " reply not received from server.");
        }
	/* Fill in */
    }

    /* Destructor. Closes the connection if something bad happens. */
    protected void finalize() throws Throwable {
	if(isConnected) {
	    close();
	}
	super.finalize();
    }
}