/*

 *   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);

		}

	}

}