/*

 *   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 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;

/**

 * 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 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

          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 e)

          {

            e.printStackTrace();

            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;

          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 = 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

  {

    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].contains(host + "!"))

      {

        Log.get().info(article.getMessageID() + " skipped for host " + 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

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

              success = true;

            }

            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");

        }

      }

      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");

      }

    }

  }

}