/*
    * 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.appender;
  
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.Serializable;
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  import java.nio.channels.FileLock;
  import java.nio.file.FileSystems;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.nio.file.attribute.FileOwnerAttributeView;
  import java.nio.file.attribute.PosixFileAttributeView;
  import java.nio.file.attribute.PosixFilePermission;
  import java.nio.file.attribute.PosixFilePermissions;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.logging.log4j.core.Layout;
  import org.apache.logging.log4j.core.LoggerContext;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.util.Constants;
  import org.apache.logging.log4j.core.util.FileUtils;
  
  
  /**
   * Manages actual File I/O for File Appenders.
   */
  public class FileManager extends OutputStreamManager {
  
      private static final FileManagerFactory FACTORY = new FileManagerFactory();
  
      private final boolean isAppend;
      private final boolean createOnDemand;
      private final boolean isLocking;
      private final String advertiseURI;
      private final int bufferSize;
      private final Set<PosixFilePermission> filePermissions;
      private final String fileOwner;
      private final String fileGroup;
      private final boolean attributeViewEnabled;
  
      /**
       * @deprecated
       */
      @Deprecated
      protected FileManager(final String fileName, final OutputStream os, final boolean append, final boolean locking,
              final String advertiseURI, final Layout<? extends Serializable> layout, final int bufferSize,
              final boolean writeHeader) {
          this(fileName, os, append, locking, advertiseURI, layout, writeHeader, ByteBuffer.wrap(new byte[bufferSize]));
      }
  
      /**
       * @deprecated
       * @since 2.6
       */
      @Deprecated
      protected FileManager(final String fileName, final OutputStream os, final boolean append, final boolean locking,
              final String advertiseURI, final Layout<? extends Serializable> layout, final boolean writeHeader,
              final ByteBuffer buffer) {
          super(os, fileName, layout, writeHeader, buffer);
          this.isAppend = append;
          this.createOnDemand = false;
          this.isLocking = locking;
          this.advertiseURI = advertiseURI;
          this.bufferSize = buffer.capacity();
          this.filePermissions = null;
          this.fileOwner = null;
          this.fileGroup = null;
          this.attributeViewEnabled = false;
      }
  
      /**
       * @deprecated
       * @since 2.7
       */
      @Deprecated
      protected FileManager(final LoggerContext loggerContext, final String fileName, final OutputStream os, final boolean append, final boolean locking,
              final boolean createOnDemand, final String advertiseURI, final Layout<? extends Serializable> layout,
             final boolean writeHeader, final ByteBuffer buffer) {
         super(loggerContext, os, fileName, createOnDemand, layout, writeHeader, buffer);
         this.isAppend = append;
         this.createOnDemand = createOnDemand;
         this.isLocking = locking;
         this.advertiseURI = advertiseURI;
         this.bufferSize = buffer.capacity();
         this.filePermissions = null;
         this.fileOwner = null;
         this.fileGroup = null;
         this.attributeViewEnabled = false;
     }
 
     /**
      * @since 2.9
      */
     protected FileManager(final LoggerContext loggerContext, final String fileName, final OutputStream os, final boolean append, final boolean locking,
             final boolean createOnDemand, final String advertiseURI, final Layout<? extends Serializable> layout,
             final String filePermissions, final String fileOwner, final String fileGroup, final boolean writeHeader,
             final ByteBuffer buffer) {
         super(loggerContext, os, fileName, createOnDemand, layout, writeHeader, buffer);
         this.isAppend = append;
         this.createOnDemand = createOnDemand;
         this.isLocking = locking;
         this.advertiseURI = advertiseURI;
         this.bufferSize = buffer.capacity();
 
         final Set<String> views = FileSystems.getDefault().supportedFileAttributeViews();
         if (views.contains("posix")) {
             this.filePermissions = filePermissions != null ? PosixFilePermissions.fromString(filePermissions) : null;
             this.fileGroup = fileGroup;
         } else {
             this.filePermissions = null;
             this.fileGroup = null;
             if (filePermissions != null) {
                 LOGGER.warn("Posix file attribute permissions defined but it is not supported by this files system.");
             }
             if (fileGroup != null) {
                 LOGGER.warn("Posix file attribute group defined but it is not supported by this files system.");
             }
         }
 
         if (views.contains("owner")) {
             this.fileOwner = fileOwner;
         } else {
             this.fileOwner = null;
             if (fileOwner != null) {
                 LOGGER.warn("Owner file attribute defined but it is not supported by this files system.");
             }
         }
 
         // Supported and defined
         this.attributeViewEnabled = this.filePermissions != null || this.fileOwner != null || this.fileGroup != null;
     }
 
     /**
      * Returns the FileManager.
      * @param fileName The name of the file to manage.
      * @param append true if the file should be appended to, false if it should be overwritten.
      * @param locking true if the file should be locked while writing, false otherwise.
      * @param bufferedIo true if the contents should be buffered as they are written.
      * @param createOnDemand true if you want to lazy-create the file (a.k.a. on-demand.)
      * @param advertiseUri the URI to use when advertising the file
      * @param layout The layout
      * @param bufferSize buffer size for buffered IO
      * @param filePermissions File permissions
      * @param fileOwner File owner
      * @param fileOwner File group
      * @param configuration The configuration.
      * @return A FileManager for the File.
      */
     public static FileManager getFileManager(final String fileName, final boolean append, boolean locking,
             final boolean bufferedIo, final boolean createOnDemand, final String advertiseUri,
             final Layout<? extends Serializable> layout,
             final int bufferSize, final String filePermissions, final String fileOwner, final String fileGroup,
             final Configuration configuration) {
 
         if (locking && bufferedIo) {
             locking = false;
         }
         return narrow(FileManager.class, getManager(fileName, new FactoryData(append, locking, bufferedIo, bufferSize,
                 createOnDemand, advertiseUri, layout, filePermissions, fileOwner, fileGroup, configuration), FACTORY));
     }
 
     @Override
     protected OutputStream createOutputStream() throws IOException {
         final String filename = getFileName();
         LOGGER.debug("Now writing to {} at {}", filename, new Date());
         final FileOutputStream fos = new FileOutputStream(filename, isAppend);
         defineAttributeView(Paths.get(filename));
         return fos;
     }
 
     protected void defineAttributeView(final Path path) {
         if (attributeViewEnabled) {
             try {
                 // FileOutputStream may not create new file on all jvm
                 path.toFile().createNewFile();
 
                 FileUtils.defineFilePosixAttributeView(path, filePermissions, fileOwner, fileGroup);
             } catch (final Exception e) {
                 LOGGER.error("Could not define attribute view on path \"{}\" got {}", path, e.getMessage(), e);
             }
         }
     }
 
     @Override
     protected synchronized void write(final byte[] bytes, final int offset, final int length,
             final boolean immediateFlush) {
         if (isLocking) {
             try {
                 @SuppressWarnings("resource")
                 final FileChannel channel = ((FileOutputStream) getOutputStream()).getChannel();
                 /*
                  * Lock the whole file. This could be optimized to only lock from the current file position. Note that
                  * locking may be advisory on some systems and mandatory on others, so locking just from the current
                  * position would allow reading on systems where locking is mandatory. Also, Java 6 will throw an
                  * exception if the region of the file is already locked by another FileChannel in the same JVM.
                  * Hopefully, that will be avoided since every file should have a single file manager - unless two
                  * different files strings are configured that somehow map to the same file.
                  */
                 try (final FileLock lock = channel.lock(0, Long.MAX_VALUE, false)) {
                     super.write(bytes, offset, length, immediateFlush);
                 }
             } catch (final IOException ex) {
                 throw new AppenderLoggingException("Unable to obtain lock on " + getName(), ex);
             }
         } else {
             super.write(bytes, offset, length, immediateFlush);
         }
     }
 
     /**
      * Overrides {@link OutputStreamManager#writeToDestination(byte[], int, int)} to add support for file locking.
      *
      * @param bytes the array containing data
      * @param offset from where to write
      * @param length how many bytes to write
      * @since 2.8
      */
     @Override
     protected synchronized void writeToDestination(final byte[] bytes, final int offset, final int length) {
         if (isLocking) {
             try {
                 @SuppressWarnings("resource")
                 final FileChannel channel = ((FileOutputStream) getOutputStream()).getChannel();
                 /*
                  * Lock the whole file. This could be optimized to only lock from the current file position. Note that
                  * locking may be advisory on some systems and mandatory on others, so locking just from the current
                  * position would allow reading on systems where locking is mandatory. Also, Java 6 will throw an
                  * exception if the region of the file is already locked by another FileChannel in the same JVM.
                  * Hopefully, that will be avoided since every file should have a single file manager - unless two
                  * different files strings are configured that somehow map to the same file.
                  */
                 try (final FileLock lock = channel.lock(0, Long.MAX_VALUE, false)) {
                     super.writeToDestination(bytes, offset, length);
                 }
             } catch (final IOException ex) {
                 throw new AppenderLoggingException("Unable to obtain lock on " + getName(), ex);
             }
         } else {
             super.writeToDestination(bytes, offset, length);
         }
     }
 
     /**
      * Returns the name of the File being managed.
      * @return The name of the File being managed.
      */
     public String getFileName() {
         return getName();
     }
     /**
      * Returns the append status.
      * @return true if the file will be appended to, false if it is overwritten.
      */
     public boolean isAppend() {
         return isAppend;
     }
 
     /**
      * Returns the lazy-create.
      * @return true if the file will be lazy-created.
      */
     public boolean isCreateOnDemand() {
         return createOnDemand;
     }
 
     /**
      * Returns the lock status.
      * @return true if the file will be locked when writing, false otherwise.
      */
     public boolean isLocking() {
         return isLocking;
     }
 
     /**
      * Returns the buffer size to use if the appender was configured with BufferedIO=true, otherwise returns a negative
      * number.
      * @return the buffer size, or a negative number if the output stream is not buffered
      */
     public int getBufferSize() {
         return bufferSize;
     }
 
     /**
      * Returns posix file permissions if defined and the OS supports posix file attribute,
      * null otherwise.
      * @return File posix permissions
      * @see PosixFileAttributeView
      */
     public Set<PosixFilePermission> getFilePermissions() {
         return filePermissions;
     }
 
     /**
      * Returns file owner if defined and the OS supports owner file attribute view,
      * null otherwise.
      * @return File owner
      * @see FileOwnerAttributeView
      */
     public String getFileOwner() {
         return fileOwner;
     }
 
     /**
      * Returns file group if defined and the OS supports posix/group file attribute view,
      * null otherwise.
      * @return File group
      * @see PosixFileAttributeView
      */
     public String getFileGroup() {
         return fileGroup;
     }
 
     /**
      * Returns true if file attribute view enabled for this file manager.
      *
      * @return True if posix or owner supported and defined false otherwise.
      */
     public boolean isAttributeViewEnabled() {
         return attributeViewEnabled;
     }
 
     /**
      * FileManager's content format is specified by: <code>Key: "fileURI" Value: provided "advertiseURI" param</code>.
      *
      * @return Map of content format keys supporting FileManager
      */
     @Override
     public Map<String, String> getContentFormat() {
         final Map<String, String> result = new HashMap<>(super.getContentFormat());
         result.put("fileURI", advertiseURI);
         return result;
     }
 
     /**
      * Factory Data.
      */
     private static class FactoryData extends ConfigurationFactoryData {
         private final boolean append;
         private final boolean locking;
         private final boolean bufferedIo;
         private final int bufferSize;
         private final boolean createOnDemand;
         private final String advertiseURI;
         private final Layout<? extends Serializable> layout;
         private final String filePermissions;
         private final String fileOwner;
         private final String fileGroup;
 
         /**
          * Constructor.
          * @param append Append status.
          * @param locking Locking status.
          * @param bufferedIo Buffering flag.
          * @param bufferSize Buffer size.
          * @param createOnDemand if you want to lazy-create the file (a.k.a. on-demand.)
          * @param advertiseURI the URI to use when advertising the file
          * @param layout The layout
          * @param filePermissions File permissions
          * @param fileOwner File owner
          * @param fileGroup File group
          * @param configuration the configuration
          */
         public FactoryData(final boolean append, final boolean locking, final boolean bufferedIo, final int bufferSize,
                 final boolean createOnDemand, final String advertiseURI, final Layout<? extends Serializable> layout,
                 final String filePermissions, final String fileOwner, final String fileGroup,
                 final Configuration configuration) {
             super(configuration);
             this.append = append;
             this.locking = locking;
             this.bufferedIo = bufferedIo;
             this.bufferSize = bufferSize;
             this.createOnDemand = createOnDemand;
             this.advertiseURI = advertiseURI;
             this.layout = layout;
             this.filePermissions = filePermissions;
             this.fileOwner = fileOwner;
             this.fileGroup = fileGroup;
         }
     }
 
     /**
      * Factory to create a FileManager.
      */
     private static class FileManagerFactory implements ManagerFactory<FileManager, FactoryData> {
 
         /**
          * Creates a FileManager.
          * @param name The name of the File.
          * @param data The FactoryData
          * @return The FileManager for the File.
          */
         @Override
         public FileManager createManager(final String name, final FactoryData data) {
             final File file = new File(name);
             try {
                 FileUtils.makeParentDirs(file);
                 final boolean writeHeader = !data.append || !file.exists();
                 final int actualSize = data.bufferedIo ? data.bufferSize : Constants.ENCODER_BYTE_BUFFER_SIZE;
                 final ByteBuffer byteBuffer = ByteBuffer.wrap(new byte[actualSize]);
                 final FileOutputStream fos = data.createOnDemand ? null : new FileOutputStream(file, data.append);
                 final FileManager fm = new FileManager(data.getLoggerContext(), name, fos, data.append, data.locking,
                         data.createOnDemand, data.advertiseURI, data.layout,
                         data.filePermissions, data.fileOwner, data.fileGroup, writeHeader, byteBuffer);
                 if (fos != null && fm.attributeViewEnabled) {
                     fm.defineAttributeView(file.toPath());
                 }
                 return fm;
             } catch (final IOException ex) {
                 LOGGER.error("FileManager (" + name + ") " + ex, ex);
             }
             return null;
         }
     }
 
 }