/*

 *   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.daemon.command;

import java.io.IOException;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.sql.SQLException;

import java.util.Arrays;

import java.util.logging.Level;

import javax.mail.MessagingException;

import javax.mail.internet.AddressException;

import javax.mail.internet.InternetHeaders;

import org.sonews.config.Config;

import org.sonews.util.Log;

import org.sonews.mlgw.Dispatcher;

import org.sonews.storage.Article;

import org.sonews.storage.Group;

import org.sonews.daemon.NNTPConnection;

import org.sonews.storage.Headers;

import org.sonews.storage.StorageBackendException;

import org.sonews.storage.StorageManager;

import org.sonews.feed.FeedManager;

import org.sonews.util.Stats;

import org.sonews.util.io.SMTPInputStream;

/**

 * Implementation of the POST command. This command requires multiple lines

 * from the client, so the handling of asynchronous reading is a little tricky

 * to handle.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class PostCommand implements Command {

	private final Article article = new Article();

	private int lineCount = 0;

	private long bodySize = 0;

	private InternetHeaders headers = null;

	private long maxBodySize =

			Config.inst().get(Config.ARTICLE_MAXSIZE, 128) * 1024L; // Size in bytes

	private PostState state = PostState.WaitForLineOne;

	private final ByteArrayOutputStream bufBody = new ByteArrayOutputStream();

	private final StringBuilder strHead = new StringBuilder();

	@Override

	public String[] getSupportedCommandStrings() {

		return new String[]{"POST"};

	}

	@Override

	public boolean hasFinished() {

		return this.state == PostState.Finished;

	}

	@Override

	public String impliedCapability() {

		return null;

	}

	@Override

	public boolean isStateful() {

		return true;

	}

	/**

	 * Process the given line String. line.trim() was called by NNTPConnection.

	 * @param line

	 * @throws java.io.IOException

	 * @throws java.sql.SQLException

	 */

	@Override // TODO: Refactor this method to reduce complexity!

	public void processLine(NNTPConnection conn, String line, byte[] raw)

			throws IOException, StorageBackendException {

		switch (state) {

			case WaitForLineOne: {

				if (line.equalsIgnoreCase("POST")) {

					conn.println("340 send article to be posted. End with <CR-LF>.<CR-LF>");

					state = PostState.ReadingHeaders;

				} else {

					conn.println("500 invalid command usage");

				}

				break;

			}

			case ReadingHeaders: {

				strHead.append(line);

				strHead.append(NNTPConnection.NEWLINE);

				if ("".equals(line) || ".".equals(line)) {

					// we finally met the blank line

					// separating headers from body

					// WTF: "."

					try {

						// Parse the header using the InternetHeader class from JavaMail API

						headers = new InternetHeaders(

								new ByteArrayInputStream(strHead.toString().trim().getBytes(conn.getCurrentCharset())));

						// add the header entries for the article

						article.setHeaders(headers);

					} catch (MessagingException ex) {

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

						conn.println("500 posting failed - invalid header");

						state = PostState.Finished;

						break;

					}

					// Change charset for reading body;

					// for multipart messages UTF-8 is returned

					//conn.setCurrentCharset(article.getBodyCharset());

					state = PostState.ReadingBody;

					// WTF: do we need articles without bodies?

					if (".".equals(line)) {

						// Post an article without body

						postArticle(conn, article);

						state = PostState.Finished;

					}

				}

				break;

			}

			case ReadingBody: {

				if (".".equals(line)) {

					// Set some headers needed for Over command

					headers.setHeader(Headers.LINES, Integer.toString(lineCount));

					headers.setHeader(Headers.BYTES, Long.toString(bodySize));

					byte[] body = unescapeDots(bufBody.toByteArray());

					if (body.length >= 2) {

						// Remove trailing CRLF

						body = Arrays.copyOf(body, body.length - 2);

					}

					article.setBody(body); // set the article body

					postArticle(conn, article);

					state = PostState.Finished;

				} else {

					bodySize += line.length() + 1;

					lineCount++;

					// Add line to body buffer

					bufBody.write(raw, 0, raw.length);

					bufBody.write(NNTPConnection.NEWLINE.getBytes());

					if (bodySize > maxBodySize) {

						conn.println("500 article is too long");

						state = PostState.Finished;

						break;

					}

				}

				break;

			}

			default: {

				// Should never happen

				Log.get().severe("PostCommand::processLine(): already finished...");

			}

		}

	}

	/**

	 * Article is a control message and needs special handling.

	 * @param article

	 */

	private void controlMessage(NNTPConnection conn, Article article)

			throws IOException {

		String[] ctrl = article.getHeader(Headers.CONTROL)[0].split(" ");

		if (ctrl.length == 2) // "cancel <mid>"

		{

			try {

				StorageManager.current().delete(ctrl[1]);

				// Move cancel message to "control" group

				article.setHeader(Headers.NEWSGROUPS, "control");

				StorageManager.current().addArticle(article);

				conn.println("240 article cancelled");

			} catch (StorageBackendException ex) {

				Log.get().severe(ex.toString());

				conn.println("500 internal server error");

			}

		} else {

			conn.println("441 unknown control header");

		}

	}

	private void supersedeMessage(NNTPConnection conn, Article article)

			throws IOException {

		try {

			String oldMsg = article.getHeader(Headers.SUPERSEDES)[0];

			StorageManager.current().delete(oldMsg);

			StorageManager.current().addArticle(article);

			conn.println("240 article replaced");

		} catch (StorageBackendException ex) {

			Log.get().severe(ex.toString());

			conn.println("500 internal server error");

		}

	}

	private void postArticle(NNTPConnection conn, Article article)

			throws IOException {

		article.setUser(conn.getUser());

		if (article.getHeader(Headers.CONTROL)[0].length() > 0) {

			controlMessage(conn, article);

		} else if (article.getHeader(Headers.SUPERSEDES)[0].length() > 0) {

			supersedeMessage(conn, article);

		} else { // Post the article regularily

			// Circle check; note that Path can already contain the hostname here

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

			if (article.getHeader(Headers.PATH)[0].indexOf(host + "!", 1) > 0) {

				Log.get().log(Level.INFO, "{0} skipped for host {1}", new Object[]{article.getMessageID(), host});

				conn.println("441 I know this article already");

				return;

			}

			// Try to create the article in the database or post it to

			// appropriate mailing list

			try {

				boolean success = false;

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

				for (String groupname : groupnames) {

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

					if (group != null && !group.isDeleted()) {

						if (group.isMailingList() && !conn.isLocalConnection()) {

							// Send to mailing list; the Dispatcher writes

							// statistics to database

							success = Dispatcher.toList(article, group.getName());

						} else {

							// Store in database

							if (!StorageManager.current().isArticleExisting(article.getMessageID())) {

								StorageManager.current().addArticle(article);

								// Log this posting to statistics

								Stats.getInstance().mailPosted(

										article.getHeader(Headers.NEWSGROUPS)[0]);

							}

							success = true;

						}

					}

				} // end for

				if (success) {

					conn.println("240 article posted ok");

					FeedManager.queueForPush(article);

				} else {

					conn.println("441 newsgroup not found or configuration error");

				}

			} catch (AddressException ex) {

				Log.get().warning(ex.getMessage());

				conn.println("441 invalid sender address");

			} catch (MessagingException ex) {

				// A MessageException is thrown when the sender email address is

				// invalid or something is wrong with the SMTP server.

				System.err.println(ex.getLocalizedMessage());

				conn.println("441 " + ex.getClass().getCanonicalName() + ": " + ex.getLocalizedMessage());

			} catch (StorageBackendException ex) {

				ex.printStackTrace();

				conn.println("500 internal server error");

			}

		}

	}

	/**

	 * TODO: rework, integrate into NNTPConnection

	 * 

	 * @param body message body with doubled dots

	 * @return message body with unescaped dots (.. → .)

	 */

	private static byte[] unescapeDots(byte[] body) throws IOException {

		byte[] result = new byte[body.length];

		int resultLength = 0;

		ByteArrayInputStream escapedInput = new ByteArrayInputStream(body);

		SMTPInputStream unescapedInput = new SMTPInputStream(escapedInput);

		int ch = unescapedInput.read();

		while (ch >= 0) {

			result[resultLength] = (byte) ch;

			resultLength++;

			ch = unescapedInput.read();

		}

		return Arrays.copyOfRange(result, 0, resultLength);

	}

}