/*

 *   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.storage;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.util.UUID;

import java.util.ArrayList;

import java.util.Enumeration;

import java.util.List;

import java.util.logging.Level;

import javax.mail.Header;

import javax.mail.Message;

import javax.mail.MessagingException;

import javax.mail.internet.InternetHeaders;

import org.sonews.config.Config;

import org.sonews.util.Log;

/**

 * Represents a newsgroup article.

 * @author Christian Lins

 * @author Denis Schwerdel

 * @since n3tpd/0.1

 */

public class Article extends ArticleHead {

	/**

	 * Loads the Article identified by the given ID from the JDBCDatabase.

	 * @param messageID

	 * @return null if Article is not found or if an error occurred.

	 */

	public static Article getByMessageID(final String messageID) {

		try {

			return StorageManager.current().getArticle(messageID);

		} catch (StorageBackendException ex) {

			Log.get().log(Level.WARNING, ex.getLocalizedMessage(), ex);

			return null;

		}

	}

	private byte[] body = new byte[0];

	/**

	 * Default constructor.

	 */

	public Article() {

	}

	/**

	 * Creates a new Article object using the date from the given

	 * raw data.

	 */

	public Article(String headers, byte[] body) {

		try {

			this.body = body;

			// Parse the header

			this.headers = new InternetHeaders(

					new ByteArrayInputStream(headers.getBytes()));

			this.headerSrc = headers;

		} catch (MessagingException ex) {

			Log.get().log(Level.WARNING, ex.getLocalizedMessage(), ex);

		}

	}

	/**

	 * Creates an Article instance using the data from the javax.mail.Message

	 * object. This constructor is called by the Mailinglist gateway.

	 * @see javax.mail.Message

	 * @param msg

	 * @throws IOException

	 * @throws MessagingException

	 */

	public Article(final Message msg)

			throws IOException, MessagingException {

		this.headers = new InternetHeaders();

		for (Enumeration e = msg.getAllHeaders(); e.hasMoreElements();) {

			final Header header = (Header) e.nextElement();

			this.headers.addHeader(header.getName(), header.getValue());

		}

		// Reads the raw byte body using Message.writeTo(OutputStream out)

		this.body = readContent(msg);

		// Validate headers

		validateHeaders();

	}

	/**

	 * Reads from the given Message into a byte array.

	 * @param in

	 * @return

	 * @throws IOException

	 */

	private byte[] readContent(Message in)

			throws IOException, MessagingException {

		ByteArrayOutputStream out = new ByteArrayOutputStream();

		in.writeTo(out);

		return out.toByteArray();

	}

	/**

	 * Removes the header identified by the given key.

	 * @param headerKey

	 */

	public void removeHeader(final String headerKey) {

		this.headers.removeHeader(headerKey);

		this.headerSrc = null;

	}

	/**

	 * Generates a message id for this article and sets it into

	 * the header object. You have to update the JDBCDatabase manually to make this

	 * change persistent.

	 * Note: a Message-ID should never be changed and only generated once.

	 */

	private String generateMessageID() {

		String randomString;

		MessageDigest md5;

		try {

			md5 = MessageDigest.getInstance("MD5");

			md5.reset();

			md5.update(getBody());

			md5.update(getHeader(Headers.SUBJECT)[0].getBytes());

			md5.update(getHeader(Headers.FROM)[0].getBytes());

			byte[] result = md5.digest();

			StringBuilder hexString = new StringBuilder();

			for (int i = 0; i < result.length; i++) {

				hexString.append(Integer.toHexString(0xFF & result[i]));

			}

			randomString = hexString.toString();

		} catch (NoSuchAlgorithmException ex) {

			Log.get().log(Level.WARNING, ex.getLocalizedMessage(), ex);

			randomString = UUID.randomUUID().toString();

		}

		String msgID = "<" + randomString + "@"

				+ Config.inst().get(Config.HOSTNAME, "localhost") + ">";

		this.headers.setHeader(Headers.MESSAGE_ID, msgID);

		return msgID;

	}

	/**

	 * Returns the body string.

	 */

	public byte[] getBody() {

		return body;

	}

	/**

	 * @return Numerical IDs of the newsgroups this Article belongs to.

	 */

	public List<Group> getGroups() {

		String[] groupnames = getHeader(Headers.NEWSGROUPS)[0].split(",");

		ArrayList<Group> groups = new ArrayList<Group>();

		try {

			for (String newsgroup : groupnames) {

				newsgroup = newsgroup.trim();

				Group group = StorageManager.current().getGroup(newsgroup);

				if (group != null && // If the server does not provide the group, ignore it

						!groups.contains(group)) // Yes, there may be duplicates

				{

					groups.add(group);

				}

			}

		} catch (StorageBackendException ex) {

			Log.get().log(Level.WARNING, ex.getLocalizedMessage(), ex);

			return null;

		}

		return groups;

	}

	public void setBody(byte[] body) {

		this.body = body;

	}

	/**

	 *

	 * @param groupname Name(s) of newsgroups

	 */

	public void setGroup(String groupname) {

		this.headers.setHeader(Headers.NEWSGROUPS, groupname);

	}

	/**

	 * Returns the Message-ID of this Article. If the appropriate header

	 * is empty, a new Message-ID is created.

	 * @return Message-ID of this Article.

	 */

	public String getMessageID() {

		String[] msgID = getHeader(Headers.MESSAGE_ID);

		return msgID[0].equals("") ? generateMessageID() : msgID[0];

	}

	/**

	 * @return String containing the Message-ID.

	 */

	@Override

	public String toString() {

		return getMessageID();

	}

}