/*

  *   SONEWS News Server

  *   see AUTHORS for the list of contributors

  *

  *   This program is free software: you can redistribute it and/or modify

  *   it under the terms of the GNU General Public License as published by

  *   the Free Software Foundation, either version 3 of the License, or

  *   (at your option) any later version.

  *

  *   This program is distributed in the hope that it will be useful,

  *   but WITHOUT ANY WARRANTY; without even the implied warranty of

  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  *   GNU General Public License for more details.

  *

  *   You should have received a copy of the GNU General Public License

  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.

  */

 package org.sonews.mlgw;

 import java.io.BufferedOutputStream;

 import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStreamReader;

 import java.io.UnsupportedEncodingException;

 import java.net.Socket;

 import java.net.UnknownHostException;

 import java.util.ArrayList;

 import java.util.List;

 import org.apache.commons.codec.binary.Base64;

 import org.sonews.config.Config;

 import org.sonews.storage.Article;

 import org.sonews.util.io.ArticleInputStream;

 /**

  * Connects to a SMTP server and sends a given Article to it.

  * @author Christian Lins

  * @since sonews/1.0

  */

 class SMTPTransport {

 	public static final String NEWLINE = "\r\n";

 	protected BufferedReader in;

 	protected BufferedOutputStream out;

 	protected Socket socket;

 	public SMTPTransport(String host, int port)

 			throws IOException, UnknownHostException {

 		this.socket = new Socket(host, port);

 		this.in = new BufferedReader(

 				new InputStreamReader(socket.getInputStream()));

 		this.out = new BufferedOutputStream(socket.getOutputStream());

 		// Read HELO from server

 		String line = this.in.readLine();

 		if (line == null || !line.startsWith("220 ")) {

 			throw new IOException("Invalid HELO from server: " + line);

 		}

 	}

 	public void close()

 			throws IOException {

 		this.out.write("QUIT".getBytes("UTF-8"));

 		this.out.flush();

 		this.in.readLine();

 		this.socket.close();

 	}

 	private byte[] createCredentials() throws UnsupportedEncodingException {

 		String user = Config.inst().get(Config.MLSEND_USER, "");

 		String pass = Config.inst().get(Config.MLSEND_PASSWORD, "");

 		StringBuilder credBuf = new StringBuilder();

 		credBuf.append(user);

 		credBuf.append("\u0000");

 		credBuf.append(pass);

 		return Base64.encodeBase64(credBuf.toString().getBytes("UTF-8"));

 	}

 	private void ehlo(String hostname) throws IOException {

 		StringBuilder strBuf = new StringBuilder();

 		strBuf.append("EHLO ");

 		strBuf.append(hostname);

 		strBuf.append(NEWLINE);

 		// Send EHLO to server

 		this.out.write(strBuf.toString().getBytes("UTF-8"));

 		this.out.flush();

 		List<String> ehloReplies = readReply("250");

 		// TODO: Check for supported methods

 		// Do a PLAIN login

 		strBuf = new StringBuilder();

 		strBuf.append("AUTH PLAIN");

 		strBuf.append(NEWLINE);

 		// Send AUTH to server

 		this.out.write(strBuf.toString().getBytes("UTF-8"));

 		this.out.flush();

 		readReply("334");

 		// Send PLAIN credentials to server

 		this.out.write(createCredentials());

 		this.out.flush();

 		// Read reply of successful login

 		readReply("235");

 	}

 	private void helo(String hostname) throws IOException {

 		StringBuilder heloStr = new StringBuilder();

 		heloStr.append("HELO ");

 		heloStr.append(hostname);

 		heloStr.append(NEWLINE);

 		// Send HELO to server

 		this.out.write(heloStr.toString().getBytes("UTF-8"));

 		this.out.flush();

 		// Read reply

 		readReply("250");

 	}

 	public void login() throws IOException {

 		String hostname = Config.inst().get(Config.HOSTNAME, "localhost");

 		String auth = Config.inst().get(Config.MLSEND_AUTH, "none");

 		if(auth.equals("none")) {

 			helo(hostname);

 		} else {

 			ehlo(hostname);

 		}

 	}

 	/**

 	 * Read one or more exspected reply lines.

 	 * @param expectedReply

 	 * @return

 	 * @throws IOException If the reply of the server does not fit the exspected

 	 * reply code.

 	 */

 	private List<String> readReply(String expectedReply) throws IOException {

 		List<String> replyStrings = new ArrayList<String>();

 		for(;;) {

 			String line = this.in.readLine();

 			if (line == null || !line.startsWith(expectedReply)) {

 				throw new IOException("Unexpected reply: " + line);

 			}

 			replyStrings.add(line);

 			if(line.charAt(3) == ' ') { // Last reply line

 				break;

 			}

 		}

 		return replyStrings;

 	}

 	public void send(Article article, String mailFrom, String rcptTo)

 			throws IOException {

 		assert (article != null);

 		assert (mailFrom != null);

 		assert (rcptTo != null);

 		this.out.write(("MAIL FROM: " + mailFrom).getBytes("UTF-8"));

 		this.out.flush();

 		String line = this.in.readLine();

 		if (line == null || !line.startsWith("250 ")) {

 			throw new IOException("Unexpected reply: " + line);

 		}

 		this.out.write(("RCPT TO: " + rcptTo).getBytes("UTF-8"));

 		this.out.flush();

 		line = this.in.readLine();

 		if (line == null || !line.startsWith("250 ")) {

 			throw new IOException("Unexpected reply: " + line);

 		}

 		this.out.write("DATA".getBytes("UTF-8"));

 		this.out.flush();

 		line = this.in.readLine();

 		if (line == null || !line.startsWith("354 ")) {

 			throw new IOException("Unexpected reply: " + line);

 		}

 		ArticleInputStream artStream = new ArticleInputStream(article);

 		for (int b = artStream.read(); b >= 0; b = artStream.read()) {

 			this.out.write(b);

 		}

 		// Flush the binary stream; important because otherwise the output

 		// will be mixed with the PrintWriter.

 		this.out.flush();

 		this.out.write("\r\n.\r\n".getBytes("UTF-8"));

 		this.out.flush();

 		line = this.in.readLine();

 		if (line == null || !line.startsWith("250 ")) {

 			throw new IOException("Unexpected reply: " + line);

 		}

 	}

 }