/*
    * Copyright (C) 2010, Google Inc.
    * Copyright (C) 2010, Matthias Sohn <matthias.sohn@sap.com>
    * Copyright (C) 2010, Jens Baumgart <jens.baumgart@sap.com>
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
   * available at http://www.eclipse.org/org/documents/edl-v10.php
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  package org.eclipse.jgit.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.channels.FileLock;
  import java.text.MessageFormat;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.regex.Pattern;
  
  import org.eclipse.jgit.internal.JGitText;
  
  /**
   * File Utilities
   */
  public class FileUtils {
  
  	/**
  	 * Option to delete given {@code File}
  	 */
  	public static final int NONE = 0;
  
  	/**
  	 * Option to recursively delete given {@code File}
  	 */
  	public static final int RECURSIVE = 1;
  
  	/**
  	 * Option to retry deletion if not successful
  	 */
  	public static final int RETRY = 2;
  
  	/**
  	 * Option to skip deletion if file doesn't exist
  	 */
  	public static final int SKIP_MISSING = 4;
  
  	/**
  	 * Option not to throw exceptions when a deletion finally doesn't succeed.
  	 * @since 2.0
  	 */
  	public static final int IGNORE_ERRORS = 8;
  
  	/**
  	 * Option to only delete empty directories. This option can be combined with
  	 * {@link #RECURSIVE}
  	 *
  	 * @since 3.0
  	 */
  	public static final int EMPTY_DIRECTORIES_ONLY = 16;
  
  	/**
  	 * Delete file or empty folder
  	 *
 	 * @param f
 	 *            {@code File} to be deleted
 	 * @throws IOException
 	 *             if deletion of {@code f} fails. This may occur if {@code f}
 	 *             didn't exist when the method was called. This can therefore
 	 *             cause IOExceptions during race conditions when multiple
 	 *             concurrent threads all try to delete the same file.
 	 */
 	public static void delete(final File f) throws IOException {
 		delete(f, NONE);
 	}
 
 	/**
 	 * Delete file or folder
 	 *
 	 * @param f
 	 *            {@code File} to be deleted
 	 * @param options
 	 *            deletion options, {@code RECURSIVE} for recursive deletion of
 	 *            a subtree, {@code RETRY} to retry when deletion failed.
 	 *            Retrying may help if the underlying file system doesn't allow
 	 *            deletion of files being read by another thread.
 	 * @throws IOException
 	 *             if deletion of {@code f} fails. This may occur if {@code f}
 	 *             didn't exist when the method was called. This can therefore
 	 *             cause IOExceptions during race conditions when multiple
 	 *             concurrent threads all try to delete the same file. This
 	 *             exception is not thrown when IGNORE_ERRORS is set.
 	 */
 	public static void delete(final File f, int options) throws IOException {
 		FS fs = FS.DETECTED;
 		if ((options & SKIP_MISSING) != 0 && !fs.exists(f))
 			return;
 
 		if ((options & RECURSIVE) != 0 && fs.isDirectory(f)) {
 			final File[] items = f.listFiles();
 			if (items != null) {
 				List<File> files = new ArrayList<File>();
 				List<File> dirs = new ArrayList<File>();
 				for (File c : items)
 					if (c.isFile())
 						files.add(c);
 					else
 						dirs.add(c);
 				// Try to delete files first, otherwise options
 				// EMPTY_DIRECTORIES_ONLY|RECURSIVE will delete empty
 				// directories before aborting, depending on order.
 				for (File file : files)
 					delete(file, options);
 				for (File d : dirs)
 					delete(d, options);
 			}
 		}
 
 		boolean delete = false;
 		if ((options & EMPTY_DIRECTORIES_ONLY) != 0) {
 			if (f.isDirectory()) {
 				delete = true;
 			} else {
 				if ((options & IGNORE_ERRORS) == 0)
 					throw new IOException(MessageFormat.format(
 							JGitText.get().deleteFileFailed,
 							f.getAbsolutePath()));
 			}
 		} else {
 			delete = true;
 		}
 
 		if (delete && !f.delete()) {
 			if ((options & RETRY) != 0 && fs.exists(f)) {
 				for (int i = 1; i < 10; i++) {
 					try {
 						Thread.sleep(100);
 					} catch (InterruptedException e) {
 						// ignore
 					}
 					if (f.delete())
 						return;
 				}
 			}
 			if ((options & IGNORE_ERRORS) == 0)
 				throw new IOException(MessageFormat.format(
 						JGitText.get().deleteFileFailed, f.getAbsolutePath()));
 		}
 	}
 
 	/**
 	 * Rename a file or folder. If the rename fails and if we are running on a
 	 * filesystem where it makes sense to repeat a failing rename then repeat
 	 * the rename operation up to 9 times with 100ms sleep time between two
 	 * calls. Furthermore if the destination exists and is directory hierarchy
 	 * with only directories in it, the whole directory hierarchy will be
 	 * deleted. If the target represents a non-empty directory structure, empty
 	 * subdirectories within that structure may or may not be deleted even if
 	 * the method fails. Furthermore if the destination exists and is a file
 	 * then the file will be deleted and then the rename is retried.
 	 * <p>
 	 * This operation is <em>not</em> atomic.
 	 *
 	 * @see FS#retryFailedLockFileCommit()
 	 * @param src
 	 *            the old {@code File}
 	 * @param dst
 	 *            the new {@code File}
 	 * @throws IOException
 	 *             if the rename has failed
 	 * @since 3.0
 	 */
 	public static void rename(final File src, final File dst)
 			throws IOException {
 		int attempts = FS.DETECTED.retryFailedLockFileCommit() ? 10 : 1;
 		while (--attempts >= 0) {
 			if (src.renameTo(dst))
 				return;
 			try {
 				if (!dst.delete())
 					delete(dst, EMPTY_DIRECTORIES_ONLY | RECURSIVE);
 				// On *nix there is no try, you do or do not
 				if (src.renameTo(dst))
 					return;
 			} catch (IOException e) {
 				// ignore and continue retry
 			}
 			try {
 				Thread.sleep(100);
 			} catch (InterruptedException e) {
 				throw new IOException(MessageFormat.format(
 						JGitText.get().renameFileFailed, src.getAbsolutePath(),
 						dst.getAbsolutePath()));
 			}
 		}
 		throw new IOException(MessageFormat.format(
 				JGitText.get().renameFileFailed, src.getAbsolutePath(),
 				dst.getAbsolutePath()));
 	}
 
 	/**
 	 * Creates the directory named by this abstract pathname.
 	 *
 	 * @param d
 	 *            directory to be created
 	 * @throws IOException
 	 *             if creation of {@code d} fails. This may occur if {@code d}
 	 *             did exist when the method was called. This can therefore
 	 *             cause IOExceptions during race conditions when multiple
 	 *             concurrent threads all try to create the same directory.
 	 */
 	public static void mkdir(final File d)
 			throws IOException {
 		mkdir(d, false);
 	}
 
 	/**
 	 * Creates the directory named by this abstract pathname.
 	 *
 	 * @param d
 	 *            directory to be created
 	 * @param skipExisting
 	 *            if {@code true} skip creation of the given directory if it
 	 *            already exists in the file system
 	 * @throws IOException
 	 *             if creation of {@code d} fails. This may occur if {@code d}
 	 *             did exist when the method was called. This can therefore
 	 *             cause IOExceptions during race conditions when multiple
 	 *             concurrent threads all try to create the same directory.
 	 */
 	public static void mkdir(final File d, boolean skipExisting)
 			throws IOException {
 		if (!d.mkdir()) {
 			if (skipExisting && d.isDirectory())
 				return;
 			throw new IOException(MessageFormat.format(
 					JGitText.get().mkDirFailed, d.getAbsolutePath()));
 		}
 	}
 
 	/**
 	 * Creates the directory named by this abstract pathname, including any
 	 * necessary but nonexistent parent directories. Note that if this operation
 	 * fails it may have succeeded in creating some of the necessary parent
 	 * directories.
 	 *
 	 * @param d
 	 *            directory to be created
 	 * @throws IOException
 	 *             if creation of {@code d} fails. This may occur if {@code d}
 	 *             did exist when the method was called. This can therefore
 	 *             cause IOExceptions during race conditions when multiple
 	 *             concurrent threads all try to create the same directory.
 	 */
 	public static void mkdirs(final File d) throws IOException {
 		mkdirs(d, false);
 	}
 
 	/**
 	 * Creates the directory named by this abstract pathname, including any
 	 * necessary but nonexistent parent directories. Note that if this operation
 	 * fails it may have succeeded in creating some of the necessary parent
 	 * directories.
 	 *
 	 * @param d
 	 *            directory to be created
 	 * @param skipExisting
 	 *            if {@code true} skip creation of the given directory if it
 	 *            already exists in the file system
 	 * @throws IOException
 	 *             if creation of {@code d} fails. This may occur if {@code d}
 	 *             did exist when the method was called. This can therefore
 	 *             cause IOExceptions during race conditions when multiple
 	 *             concurrent threads all try to create the same directory.
 	 */
 	public static void mkdirs(final File d, boolean skipExisting)
 			throws IOException {
 		if (!d.mkdirs()) {
 			if (skipExisting && d.isDirectory())
 				return;
 			throw new IOException(MessageFormat.format(
 					JGitText.get().mkDirsFailed, d.getAbsolutePath()));
 		}
 	}
 
 	/**
 	 * Atomically creates a new, empty file named by this abstract pathname if
 	 * and only if a file with this name does not yet exist. The check for the
 	 * existence of the file and the creation of the file if it does not exist
 	 * are a single operation that is atomic with respect to all other
 	 * filesystem activities that might affect the file.
 	 * <p>
 	 * Note: this method should not be used for file-locking, as the resulting
 	 * protocol cannot be made to work reliably. The {@link FileLock} facility
 	 * should be used instead.
 	 *
 	 * @param f
 	 *            the file to be created
 	 * @throws IOException
 	 *             if the named file already exists or if an I/O error occurred
 	 */
 	public static void createNewFile(File f) throws IOException {
 		if (!f.createNewFile())
 			throw new IOException(MessageFormat.format(
 					JGitText.get().createNewFileFailed, f));
 	}
 
 	/**
 	 * Create a symbolic link
 	 *
 	 * @param path
 	 * @param target
 	 * @throws IOException
 	 * @since 3.0
 	 */
 	public static void createSymLink(File path, String target)
 			throws IOException {
 		FS.DETECTED.createSymLink(path, target);
 	}
 
 	/**
 	 * @param path
 	 * @return the target of the symbolic link, or null if it is not a symbolic
 	 *         link
 	 * @throws IOException
 	 * @since 3.0
 	 */
 	public static String readSymLink(File path) throws IOException {
 		return FS.DETECTED.readSymLink(path);
 	}
 
 	/**
 	 * Create a temporary directory.
 	 *
 	 * @param prefix
 	 * @param suffix
 	 * @param dir
 	 *            The parent dir, can be null to use system default temp dir.
 	 * @return the temp dir created.
 	 * @throws IOException
 	 * @since 3.4
 	 */
 	public static File createTempDir(String prefix, String suffix, File dir)
 			throws IOException {
 		final int RETRIES = 1; // When something bad happens, retry once.
 		for (int i = 0; i < RETRIES; i++) {
 			File tmp = File.createTempFile(prefix, suffix, dir);
 			if (!tmp.delete())
 				continue;
 			if (!tmp.mkdir())
 				continue;
 			return tmp;
 		}
 		throw new IOException(JGitText.get().cannotCreateTempDir);
 	}
 
 	/**
 	 * This will try and make a given path relative to another.
 	 * <p>
 	 * For example, if this is called with the two following paths :
 	 *
 	 * <pre>
 	 * <code>base = "c:\\Users\\jdoe\\eclipse\\git\\project"</code>
 	 * <code>other = "c:\\Users\\jdoe\\eclipse\\git\\another_project\\pom.xml"</code>
 	 * </pre>
 	 *
 	 * This will return "..\\another_project\\pom.xml".
 	 * </p>
 	 * <p>
 	 * This method uses {@link File#separator} to split the paths into segments.
 	 * </p>
 	 * <p>
 	 * <b>Note</b> that this will return the empty String if <code>base</code>
 	 * and <code>other</code> are equal.
 	 * </p>
 	 *
 	 * @param base
 	 *            The path against which <code>other</code> should be
 	 *            relativized. This will be assumed to denote the path to a
 	 *            folder and not a file.
 	 * @param other
 	 *            The path that will be made relative to <code>base</code>.
 	 * @return A relative path that, when resolved against <code>base</code>,
 	 *         will yield the original <code>other</code>.
 	 * @since 3.7
 	 */
 	public static String relativize(String base, String other) {
 		if (base.equals(other))
 			return ""; //$NON-NLS-1$
 
 		final boolean ignoreCase = !FS.DETECTED.isCaseSensitive();
 		final String[] baseSegments = base.split(Pattern.quote(File.separator));
 		final String[] otherSegments = other.split(Pattern
 				.quote(File.separator));
 
 		int commonPrefix = 0;
 		while (commonPrefix < baseSegments.length
 				&& commonPrefix < otherSegments.length) {
 			if (ignoreCase
 					&& baseSegments[commonPrefix]
 							.equalsIgnoreCase(otherSegments[commonPrefix]))
 				commonPrefix++;
 			else if (!ignoreCase
 					&& baseSegments[commonPrefix]
 							.equals(otherSegments[commonPrefix]))
 				commonPrefix++;
 			else
 				break;
 		}
 
 		final StringBuilder builder = new StringBuilder();
 		for (int i = commonPrefix; i < baseSegments.length; i++)
 			builder.append("..").append(File.separator); //$NON-NLS-1$
 		for (int i = commonPrefix; i < otherSegments.length; i++) {
 			builder.append(otherSegments[i]);
 			if (i < otherSegments.length - 1)
 				builder.append(File.separator);
 		}
 		return builder.toString();
 	}
 }