/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.core.rolling.helper;
  
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  
  import ch.qos.logback.core.CoreConstants;
  import ch.qos.logback.core.rolling.RollingFileAppender;
  import ch.qos.logback.core.rolling.RolloverFailure;
  import ch.qos.logback.core.spi.ContextAwareBase;
  import ch.qos.logback.core.util.FileUtil;
  
  
  /**
   * Utility class to help solving problems encountered while renaming files.
   *
   * @author Ceki Gulcu
   */
  public class RenameUtil extends ContextAwareBase {
  
    static String RENAMING_ERROR_URL = CoreConstants.CODES_URL+"#renamingError";
  
    /**
     * A robust file renaming method which in case of failure falls back to
     * renaming by copying. In case, the file to be renamed is open by another
     * process, renaming by copying will succeed whereas regular renaming will
     * fail. However, renaming by copying is much slower.
     *
     * @param from
     * @param to
     * @throws RolloverFailure
     */
    public void rename(String from, String to) throws RolloverFailure {
      if (from.equals(to)) {
        addWarn("From and to file are the same [" + from + "]. Skipping.");
        return;
      }
      File fromFile = new File(from);
  
      if (fromFile.exists()) {
        File toFile = new File(to);
        createMissingTargetDirsIfNecessary(toFile);
  
        addInfo("Renaming file [" + fromFile + "] to [" + toFile + "]");
  
        boolean result = fromFile.renameTo(toFile);
  
        if (!result) {
          addWarn("Failed to rename file [" + fromFile + "] to [" + toFile + "].");
          addWarn("Please consider leaving the [file] option of "+ RollingFileAppender.class.getSimpleName()+" empty.");
          addWarn("See also "+ RENAMING_ERROR_URL);
  
        }
      } else {
        throw new RolloverFailure("File [" + from + "] does not exist.");
      }
    }
  
    static final int BUF_SIZE = 32 * 1024;
  
    public void renameByCopying(String from, String to)
            throws RolloverFailure {
      try {
        FileInputStream fis = new FileInputStream(from);
        FileOutputStream fos = new FileOutputStream(to);
        byte[] inbuf = new byte[BUF_SIZE];
        int n;
  
        while ((n = fis.read(inbuf)) != -1) {
          fos.write(inbuf, 0, n);
        }
  
        fis.close();
        fos.close();
  
        File fromFile = new File(from);
  
        if (!fromFile.delete()) {
          addWarn("Could not delete " + from);
        }
      } catch (IOException ioe) {
        addError("Failed to rename file by copying", ioe);
        throw new RolloverFailure("Failed to rename file by copying");
      }
   }
 
   void createMissingTargetDirsIfNecessary(File toFile) throws RolloverFailure {
     if (FileUtil.isParentDirectoryCreationRequired(toFile)) {
       boolean result = FileUtil.createMissingParentDirectories(toFile);
       if (!result) {
         throw new RolloverFailure("Failed to create parent directories for ["
                 + toFile.getAbsolutePath() + "]");
       }
     }
   }
 
   @Override
   public String toString() {
     return "c.q.l.co.rolling.helper.RenameUtil";
   }
 }