EmailMessage.java

/*************************************
 * Filename:  EmailMessage.java
 * Date: 17/10/2019
 *************************************/

import java.util.*;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.text.*;


public class EmailMessage {
	/* SMTP-sender of the message (in this case, contents of From-header. */
	public String Sender;
	/* SMTP-recipient, or contents of To-header. */
	public String Recipient;
	/* SMTP-cc, or contents of Cc-header. */
	public String Cc;
	/* Target MX-host */
	public String DestHost;
	private InetAddress DestAddr;

  public int DestHostPort;

	/* The headers and the body of the message. */
	public String Headers;
	public String Body;

	/* To make it look nicer */
	private static final String CRLF = "\r\n";

	boolean emptyCc = false;

	/*
	 * Create the message object by inserting the required headers from RFC 822
	 * (From, To, Date).
	 */
	public EmailMessage(String to, String cc, String subject, String text,
		String localServer, int localServerPort) throws UnknownHostException {
		/* Remove whitespace */
		InetAddress id = InetAddress.getLocalHost();
		Sender = System.getProperty("user.name") + "@" + id.getHostName();
		Recipient = to.trim();
		if (cc.isEmpty()) {
			emptyCc = true;
		}
		else {
			Cc = cc.trim();
		}

		Headers = "From: " + Sender + CRLF;
		Headers += "To: " + Recipient + CRLF;
		if (!emptyCc) {
			Headers += "Cc: " + Cc + CRLF;
		}
		Headers += "Subject: " + subject.trim() + CRLF;

		/*
		 * A close approximation of the required format. Unfortunately only GMT.
		 */
		SimpleDateFormat format = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'");
		String dateString = format.format(new Date());
		Headers += "Date: " + dateString + CRLF;

		/*
		 * Get message. We must escape the message to make sure that there are
		 * no single periods on a line. This would mess up sending the mail.
		 */
		Body = escapeMessage(text);

		/*
		 * Take the name of the local mailserver and map it into an InetAddress
		 */
		DestHost = localServer;
		try {
			DestAddr = InetAddress.getByName(DestHost);
		} catch (UnknownHostException e) {
			System.out.println("Unknown host: " + DestHost);
			System.out.println(e);
			throw e;
		}
    DestHostPort = localServerPort;
	}

	/*
	 * Check whether the message is valid. In other words, check that both
	 * sender and recipient contain only one @-sign.
	 */
	public boolean isValid() {
		int fromat = Sender.indexOf('@');
		int toat = Recipient.indexOf('@');


		if (fromat < 1 || (Sender.length() - fromat) <= 1) {
			System.out.println("Sender address is invalid");
			return false;
		}
		if (fromat != Sender.lastIndexOf('@')) {
			System.out.println("Sender address is invalid");
			return false;
		}
		if (toat < 1 || (Recipient.length() - toat) <= 1) {
			System.out.println("Recipient address is invalid");
			return false;
		}
		if (toat != Recipient.lastIndexOf('@')) {
			System.out.println("Recipient address is invalid");
			return false;
		}
		return true;
	}


	/* For printing the message. */
	public String toString() {
		String res;
		int countCc=0;

		res = "Sender: " + Sender + '\n';
		res += "Recipient: " + Recipient + '\n';
		if (!emptyCc) {
			char ccDelimiter = ',';

			for(int i=0;i<Cc.length();i++){
				if(Cc.charAt(i) == ccDelimiter){
					countCc++;
				}
			}
			if(countCc>0){
				String[] ccSplitArray = Cc.split(Character.toString(ccDelimiter), countCc+1);
				for(int j=0;countCc>j;j++){
					res += "Cc: " + ccSplitArray[j] + '\n';
				}
			} else {
				res += "Cc: " + Cc + '\n';
			}

		}
		res += "MX-host: " + DestHost + ", address: " + DestAddr + '\n';
		res += "Message:" + '\n';
		res += Headers + CRLF;
		res += Body;

		return res;
	}

	/*
	 * Escape the message by doubling all periods at the beginning of a line.
	 */
	private String escapeMessage(String body) {
		String escapedBody = "";
		String token;
		StringTokenizer parser = new StringTokenizer(body, "\n", true);

		while (parser.hasMoreTokens()) {
			token = parser.nextToken();
			if (token.startsWith(".")) {
				token = "." + token;
			}
			escapedBody += token;
		}
		return escapedBody;
	}
}