/*

 *   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.io.InputStream;

import java.nio.charset.Charset;

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 javax.mail.Header;

import javax.mail.Message;

import javax.mail.MessagingException;

import javax.mail.Multipart;

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)

    {

      ex.printStackTrace();

      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)

    {

      ex.printStackTrace();

    }

  }

  /**

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

   * object.

   * @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());

    }

    // The "content" of the message can be a String if it's a simple text/plain

    // message, a Multipart object or an InputStream if the content is unknown.

    final Object content = msg.getContent();

    if(content instanceof String)

    {

      this.body = ((String)content).getBytes(getBodyCharset());

    }

    else if(content instanceof Multipart) // probably subclass MimeMultipart

    {

      // We're are not interested in the different parts of the MultipartMessage,

      // so we simply read in all data which *can* be huge.

      InputStream in = msg.getInputStream();

      this.body = readContent(in);

    }

    else if(content instanceof InputStream)

    {

      // The message format is unknown to the Message class, but we can

      // simply read in the whole message data.

      this.body = readContent((InputStream)content);

    }

    else

    {

      // Unknown content is probably a malformed mail we should skip.

      // On the other hand we produce an inconsistent mail mirror, but no

      // mail system must transport invalid content.

      Log.msg("Skipping message due to unknown content. Throwing exception...", true);

      throw new MessagingException("Unknown content: " + content);

    }

    // Validate headers

    validateHeaders();

  }

  /**

   * Reads from the given InputString into a byte array.

   * TODO: Move this generalized method to org.sonews.util.io.Resource.

   * @param in

   * @return

   * @throws IOException

   */

  private byte[] readContent(InputStream in)

    throws IOException

  {

    ByteArrayOutputStream out = new ByteArrayOutputStream();

    int b = in.read();

    while(b >= 0)

    {

      out.write(b);

      b = in.read();

    }

    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();

      StringBuffer hexString = new StringBuffer();

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

      {

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

      }

      randomString = hexString.toString();

    }

    catch (NoSuchAlgorithmException e)

    {

      e.printStackTrace();

      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 Charset of the body text

   */

  private Charset getBodyCharset()

  {

    // We espect something like 

    // Content-Type: text/plain; charset=ISO-8859-15

    String contentType = getHeader(Headers.CONTENT_TYPE)[0];

    int idxCharsetStart = contentType.indexOf("charset=") + "charset=".length();

    int idxCharsetEnd   = contentType.indexOf(";", idxCharsetStart);

    String charsetName = "UTF-8";

    if(idxCharsetStart >= 0 && idxCharsetStart < contentType.length())

    {

      if(idxCharsetEnd < 0)

      {

        charsetName = contentType.substring(idxCharsetStart);

      }

      else

      {

        charsetName = contentType.substring(idxCharsetStart, idxCharsetEnd);

      }

    }

    // Sometimes there are '"' around the name

    if(charsetName.length() > 2 &&

      charsetName.charAt(0) == '"' && charsetName.endsWith("\""))

    {

      charsetName = charsetName.substring(1, charsetName.length() - 2);

    }

    // Create charset

    Charset charset = Charset.forName("UTF-8"); // This MUST be supported by JVM

    try

    {

      charset = Charset.forName(charsetName);

    }

    catch(Exception ex)

    {

      Log.msg(ex.getMessage(), false);

      Log.msg("Article.getBodyCharset(): Unknown charset: " + charsetName, false);

    }

    return charset;

  }

  /**

   * @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)

    {

      ex.printStackTrace();

      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();

  }

}