/*
    * Copyright (c) 2005-2006 Creative Sphere Limited.
    * All rights reserved. This program and the accompanying materials
    * are made available under the terms of the Eclipse Public License v1.0
    * which accompanies this distribution, and is available at
    * http://www.eclipse.org/legal/epl-v10.html
    *
    * Contributors:
    *
   *   Creative Sphere - initial API and implementation
   *
   */
  package org.abstracthorizon.mercury.maildir.uid;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.RandomAccessFile;
  
  import javax.mail.MessagingException;
  import javax.mail.internet.MimeMessage;
  
  import org.abstracthorizon.mercury.maildir.MaildirFolderData;
  import org.abstracthorizon.mercury.maildir.MaildirMessage;
  import org.abstracthorizon.mercury.maildir.MaildirStore;
  
  /**
   * UID implementation of maildir folder model.
   *
   * @author Daniel Sendula
   */
  public class UIDMaildirFolderData extends MaildirFolderData /* implements UIDFolder TODO: nice to have */{
  
  
      /** Number of retries for .nextuid file to be read */
      public static final int MAX_RETRIES = 30;
  
  
      /** Current maxUID (last read) */
      protected long maxUid = -1;
  
      /** UID validity of this folder */
      protected long uidValidity = -1;
  
      /**
       * Constructor.
       * @param store store
       * @param file file
       */
      protected UIDMaildirFolderData(MaildirStore store, File file) {
          super(store, file);
      }
  
      /**
       * Returns max uid value
       * @return max uid value
       */
      public long getMaxUID() {
          return maxUid;
      }
  
      /**
       * This method creates new maildir message for folder data (not folder). It is expected
       * for this method to create appropriate file in proper directory based on flags in
       * supplied message (cur or new).
       * @param message message whose content will be copied to new message
       * @param num message number
       * @return new maildir message this folder will keep for its folder data
       * @throws IOException
       * @throws MessagingException
       */
      protected synchronized MaildirMessage createNewMaildirMessage(MimeMessage message, int num) throws IOException, MessagingException {
          UIDMaildirMessage msg = new UIDMaildirMessage(this, message, num);
          return msg;
      }
  
      /**
       * This method creates new maildir message object for existing file in folder data's directory.
       * @param file file message object is going to be created
       * @param num message number
       * @return new maildir message this folder will keep for its folder data
       * @throws IOException
       * @throws MessagingException
       */
      protected MaildirMessage createExistingMaildirMessage(File file, int num) throws IOException, MessagingException {
          UIDMaildirMessage msg = new UIDMaildirMessage(this, file, num);
          return msg;
      }
  
  
      /**
       * This method obtains next UID
       * @return next UID number
       * @throws MessagingException
       */
      protected synchronized UID getNextUID() throws MessagingException {
          RandomAccessFile uidFile = null;
          File file = new File(getFolderFile(), UIDMaildirStore.NEXT_UID_FILE);
          int retry = 0;
          while ((uidFile == null) && (retry < MAX_RETRIES)) {
             try {
                 uidFile = new RandomAccessFile(file, "rw");
             } catch (IOException ignore) {
             }
             if (uidFile == null) {
                 try {
                     Thread.sleep(100);
                 } catch (InterruptedException ignore) {
                 }
                 retry = retry + 1;
             }
         }
         try {
             String old = uidFile.readLine();
             long uid = 0;
             try {
                 uid = Long.parseLong(old);
             } catch (NumberFormatException ignore) {
             }
             uid = uid + 1;
             uidFile.seek(0);
             uidFile.writeBytes(Long.toString(uid));
             uidFile.close();
             maxUid = uid;
             return new UID(uid);
         } catch (IOException e) {
             throw new MessagingException("Cannot obtain next uid", e);
         } finally {
             try {
                 uidFile.close();
             } catch (IOException ignore) {
             }
         }
     }
 
     /**
      * This method returns folder's uid validity. It is read from &quot;.uidvalidity&quot;
      * @return uid validity
      */
     public long getUIDValidity() {
         if (uidValidity != -1) {
             return uidValidity;
         }
         File file = new File(getFolderFile(), UIDMaildirStore.UID_VALIDITY_FILE);
         if (file.exists()) {
             try {
                 RandomAccessFile uidFile = new RandomAccessFile(file, "r");
                 try {
                     String line = uidFile.readLine();
                     try {
                         uidValidity = Long.parseLong(line);
                     } catch (NumberFormatException ignore) {
                     }
                 } finally {
                     uidFile.close();
                 }
             } catch (IOException ignore) {
             }
         }
         if (uidValidity == -1) {
             uidValidity = System.currentTimeMillis();
             try {
                 RandomAccessFile uidFile = new RandomAccessFile(file, "rw");
                 try {
                     uidFile.writeBytes(Long.toString(uidValidity));
                 } finally {
                     uidFile.close();
                 }
             } catch (IOException ignore) {
             }
         }
         return uidValidity;
     }
 
     /**
      * Returns folder's uid validity as integer - hash code
      * @return folder's uid validity
      */
     public int hashCode() {
         return (int)getUIDValidity();
     }
 }