/*

 *   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.util.io;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.UnsupportedEncodingException;

import java.net.Socket;

import java.net.UnknownHostException;

import org.sonews.config.Config;

import org.sonews.util.Log;

/**

 * Reads an news article from a NNTP server.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class ArticleReader

{

	private BufferedOutputStream out;

	private BufferedInputStream in;

	private String messageID;

	public ArticleReader(String host, int port, String messageID)

		throws IOException, UnknownHostException

	{

		this.messageID = messageID;

		// Connect to NNTP server

		Socket socket = new Socket(host, port);

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

		this.in = new BufferedInputStream(socket.getInputStream());

		String line = readln(this.in);

		if (!line.startsWith("200 ")) {

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

		}

	}

	private boolean eofArticle(byte[] buf)

	{

		if (buf.length < 4) {

			return false;

		}

		int l = buf.length - 1;

		return buf[l - 3] == 10 // '*\n'

			&& buf[l - 2] == '.' // '.'

			&& buf[l - 1] == 13 && buf[l] == 10;  // '\r\n'

	}

	public byte[] getArticleData()

		throws IOException, UnsupportedEncodingException

	{

		long maxSize = Config.inst().get(Config.ARTICLE_MAXSIZE, 1024) * 1024L;

		try {

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

			this.out.flush();

			String line = readln(this.in);

			if (line.startsWith("220 ")) {

				ByteArrayOutputStream buf = new ByteArrayOutputStream();

				while (!eofArticle(buf.toByteArray())) {

					for (int b = in.read(); b != 10; b = in.read()) {

						buf.write(b);

					}

					buf.write(10);

					if (buf.size() > maxSize) {

						Log.get().warning("Skipping message that is too large: " + buf.size());

						return null;

					}

				}

				return buf.toByteArray();

			} else {

				Log.get().warning("ArticleReader: " + line);

				return null;

			}

		} catch (IOException ex) {

			throw ex;

		} finally {

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

			this.out.flush();

			this.out.close();

		}

	}

	private String readln(InputStream in)

		throws IOException

	{

		ByteArrayOutputStream buf = new ByteArrayOutputStream();

		for (int b = in.read(); b != 10 /* \n */; b = in.read()) {

			buf.write(b);

		}

		return new String(buf.toByteArray());

	}

}