/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache license, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the license for the specific language governing permissions and
   * limitations under the license.
   */
  package org.apache.logging.log4j.core.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.net.URL;
  import java.nio.file.FileSystems;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.attribute.GroupPrincipal;
  import java.nio.file.attribute.PosixFileAttributeView;
  import java.nio.file.attribute.PosixFilePermission;
  import java.nio.file.attribute.UserPrincipal;
  import java.nio.file.attribute.UserPrincipalLookupService;
  import java.util.Objects;
  import java.util.Set;
  
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.status.StatusLogger;
  
  /**
   * File utilities.
   */
  public final class FileUtils {
  
      /** Constant for the file URL protocol. */
      private static final String PROTOCOL_FILE = "file";
  
      private static final String JBOSS_FILE = "vfsfile";
  
      private static final Logger LOGGER = StatusLogger.getLogger();
  
      private FileUtils() {
      }
  
      /**
       * Tries to convert the specified URI to a file object. If this fails, <b>null</b> is returned.
       *
       * @param uri the URI
       * @return the resulting file object
       */
      public static File fileFromUri(URI uri) {
          if (uri == null) {
              return null;
          }
          if (uri.isAbsolute()) {
              if (JBOSS_FILE.equals(uri.getScheme())) try {
                  // patch the scheme
                  uri = new URI(PROTOCOL_FILE, uri.getSchemeSpecificPart(), uri.getFragment());
              } catch (URISyntaxException use) {
                  // should not happen, ignore
              }
              try {
                  if (PROTOCOL_FILE.equals(uri.getScheme())) {
                      return new File(uri);
                  }
              } catch (final Exception ex) {
                  LOGGER.warn("Invalid URI {}", uri);
              }
          } else {
              File file = new File(uri.toString());
              try {
                  if (file.exists()) {
                      return file;
                  }
                  final String path = uri.getPath();
                  return new File(path);
              } catch (final Exception ex) {
                  LOGGER.warn("Invalid URI {}", uri);
              }
          }
          return null;
      }
  
      public static boolean isFile(final URL url) {
          return url != null && (url.getProtocol().equals(PROTOCOL_FILE) || url.getProtocol().equals(JBOSS_FILE));
      }
  
      public static String getFileExtension(final File file) {
          final String fileName = file.getName();
          if (fileName.lastIndexOf(".") != -1 && fileName.lastIndexOf(".") != 0) {
              return fileName.substring(fileName.lastIndexOf(".") + 1);
         }
         return null;
     }
 
     /**
      * Asserts that the given directory exists and creates it if necessary.
      * 
      * @param dir the directory that shall exist
      * @param createDirectoryIfNotExisting specifies if the directory shall be created if it does not exist.
      * @throws java.io.IOException thrown if the directory could not be created.
      */
     public static void mkdir(final File dir, final boolean createDirectoryIfNotExisting) throws IOException {
         // commons io FileUtils.forceMkdir would be useful here, we just want to omit this dependency
         if (!dir.exists()) {
             if (!createDirectoryIfNotExisting) {
                 throw new IOException("The directory " + dir.getAbsolutePath() + " does not exist.");
             }
             if (!dir.mkdirs()) {
                 throw new IOException("Could not create directory " + dir.getAbsolutePath());
             }
         }
         if (!dir.isDirectory()) {
             throw new IOException("File " + dir + " exists and is not a directory. Unable to create directory.");
         }
     }
     
     /**
      * Creates the parent directories for the given File.
      * 
      * @param file
      * @throws IOException
      */
     public static void makeParentDirs(final File file) throws IOException {
         final File parent = Objects.requireNonNull(file, "file").getCanonicalFile().getParentFile();
         if (parent != null) {
             mkdir(parent, true);
         }
     }
 
     /**
      * Define file posix attribute view on a path/file.
      *
      * @param path Target path
      * @param filePermissions Permissions to apply
      * @param fileOwner File owner
      * @param fileGroup File group
      * @throws IOException If IO error during definition of file attribute view
      */
     public static void defineFilePosixAttributeView(final Path path,
             final Set<PosixFilePermission> filePermissions,
             final String fileOwner,
             final String fileGroup) throws IOException {
         final PosixFileAttributeView view = Files.getFileAttributeView(path, PosixFileAttributeView.class);
         if (view != null) {
             final UserPrincipalLookupService lookupService = FileSystems.getDefault()
                     .getUserPrincipalLookupService();
             if (fileOwner != null) {
                 final UserPrincipal userPrincipal = lookupService.lookupPrincipalByName(fileOwner);
                 if (userPrincipal != null) {
                     // If not sudoers member, it will throw Operation not permitted
                     // Only processes with an effective user ID equal to the user ID
                     // of the file or with appropriate privileges may change the ownership of a file.
                     // If _POSIX_CHOWN_RESTRICTED is in effect for path
                     view.setOwner(userPrincipal);
                 }
             }
             if (fileGroup != null) {
                 final GroupPrincipal groupPrincipal = lookupService.lookupPrincipalByGroupName(fileGroup);
                 if (groupPrincipal != null) {
                     // The current user id should be members of this group,
                     // if not will raise Operation not permitted
                     view.setGroup(groupPrincipal);
                 }
             }
             if (filePermissions != null) {
                 view.setPermissions(filePermissions);
             }
         }
     }
 
     /**
      * Check if posix file attribute view is supported on the default FileSystem.
      *
      * @return true if posix file attribute view supported, false otherwise
      */
     public static boolean isFilePosixAttributeViewSupported() {
         return FileSystems.getDefault().supportedFileAttributeViews().contains("posix");
     }
 }