/*
    * 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.rolling;
  
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.Serializable;
  import java.util.concurrent.Semaphore;
  
  import org.apache.logging.log4j.core.Layout;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.appender.FileManager;
  import org.apache.logging.log4j.core.appender.ManagerFactory;
  import org.apache.logging.log4j.core.appender.rolling.action.AbstractAction;
  import org.apache.logging.log4j.core.appender.rolling.action.Action;
  
  /**
   * The Rolling File Manager.
   */
  public class RollingFileManager extends FileManager {
  
      private static RollingFileManagerFactory factory = new RollingFileManagerFactory();
  
      private long size;
      private long initialTime;
      private final PatternProcessor patternProcessor;
      private final Semaphore semaphore = new Semaphore(1);
      private final TriggeringPolicy triggeringPolicy;
      private final RolloverStrategy rolloverStrategy;
  
      protected RollingFileManager(final String fileName, final String pattern, final OutputStream os,
              final boolean append, final long size, final long time, final TriggeringPolicy triggeringPolicy,
              final RolloverStrategy rolloverStrategy, final String advertiseURI,
              final Layout<? extends Serializable> layout, final int bufferSize, final boolean writeHeader) {
          super(fileName, os, append, false, advertiseURI, layout, bufferSize, writeHeader);
          this.size = size;
          this.initialTime = time;
          this.triggeringPolicy = triggeringPolicy;
          this.rolloverStrategy = rolloverStrategy;
          this.patternProcessor = new PatternProcessor(pattern);
          triggeringPolicy.initialize(this);
      }
  
      /**
       * Returns a RollingFileManager.
       * @param fileName The file name.
       * @param pattern The pattern for rolling file.
       * @param append true if the file should be appended to.
       * @param bufferedIO true if data should be buffered.
       * @param policy The TriggeringPolicy.
       * @param strategy The RolloverStrategy.
       * @param advertiseURI the URI to use when advertising the file
       * @param layout The Layout.
       * @param bufferSize buffer size to use if bufferedIO is true
       * @return A RollingFileManager.
       */
      public static RollingFileManager getFileManager(final String fileName, final String pattern, final boolean append,
              final boolean bufferedIO, final TriggeringPolicy policy, final RolloverStrategy strategy,
              final String advertiseURI, final Layout<? extends Serializable> layout, final int bufferSize) {
  
          return (RollingFileManager) getManager(fileName, new FactoryData(pattern, append,
              bufferedIO, policy, strategy, advertiseURI, layout, bufferSize), factory);
      }
  
      @Override
      protected synchronized void write(final byte[] bytes, final int offset, final int length) {
          size += length;
          super.write(bytes, offset, length);
      }
  
      /**
       * Returns the current size of the file.
       * @return The size of the file in bytes.
       */
      public long getFileSize() {
          return size;
      }
  
      /**
       * Returns the time the file was created.
       * @return The time the file was created.
      */
     public long getFileTime() {
         return initialTime;
     }
 
     /**
      * Determine if a rollover should occur.
      * @param event The LogEvent.
      */
     public synchronized void checkRollover(final LogEvent event) {
         if (triggeringPolicy.isTriggeringEvent(event) && rollover(rolloverStrategy)) {
             try {
                 size = 0;
                 initialTime = System.currentTimeMillis();
                 createFileAfterRollover();
             } catch (final IOException ex) {
                 LOGGER.error("FileManager (" + getFileName() + ") " + ex);
             }
         }
     }
 
     protected void createFileAfterRollover() throws IOException {
         final OutputStream os = new FileOutputStream(getFileName(), isAppend());
         if (getBufferSize() > 0) { // negative buffer size means no buffering
             setOutputStream(new BufferedOutputStream(os, getBufferSize()));
         } else {
             setOutputStream(os);
         }
     }
 
     /**
      * Returns the pattern processor.
      * @return The PatternProcessor.
      */
     public PatternProcessor getPatternProcessor() {
         return patternProcessor;
     }
 
     /**
      * Returns the triggering policy
      * @return The TriggeringPolicy
      */
     public <T extends TriggeringPolicy> T getTriggeringPolicy() {
         // TODO We could parameterize this class with a TriggeringPolicy instead of type casting here. 
         return (T) this.triggeringPolicy;
     }
 
     /**
      * Returns the rollover strategy
      * @return The RolloverStrategy
      */
     public RolloverStrategy getRolloverStrategy() {
         return this.rolloverStrategy;
     }
 
     private boolean rollover(final RolloverStrategy strategy) {
 
         try {
             // Block until the asynchronous operation is completed.
             semaphore.acquire();
         } catch (final InterruptedException ie) {
             LOGGER.error("Thread interrupted while attempting to check rollover", ie);
             return false;
         }
 
         boolean success = false;
         Thread thread = null;
 
         try {
             final RolloverDescription descriptor = strategy.rollover(this);
             if (descriptor != null) {
                 writeFooter();
                 close();
                 if (descriptor.getSynchronous() != null) {
                     LOGGER.debug("RollingFileManager executing synchronous {}", descriptor.getSynchronous());
                     try {
                         success = descriptor.getSynchronous().execute();
                     } catch (final Exception ex) {
                         LOGGER.error("Error in synchronous task", ex);
                     }
                 }
 
                 if (success && descriptor.getAsynchronous() != null) {
                     LOGGER.debug("RollingFileManager executing async {}", descriptor.getAsynchronous());
                     thread = new Thread(new AsyncAction(descriptor.getAsynchronous(), this));
                     thread.start();
                 }
                 return true;
             }
             return false;
         } finally {
             if (thread == null || !thread.isAlive()) {
                 semaphore.release();
             }
         }
 
     }
 
     /**
      * Performs actions asynchronously.
      */
     private static class AsyncAction extends AbstractAction {
 
         private final Action action;
         private final RollingFileManager manager;
 
         /**
          * Constructor.
          * @param act The action to perform.
          * @param manager The manager.
          */
         public AsyncAction(final Action act, final RollingFileManager manager) {
             this.action = act;
             this.manager = manager;
         }
 
         /**
          * Perform an action.
          *
          * @return true if action was successful.  A return value of false will cause
          *         the rollover to be aborted if possible.
          * @throws java.io.IOException if IO error, a thrown exception will cause the rollover
          *                             to be aborted if possible.
          */
         @Override
         public boolean execute() throws IOException {
             try {
                 return action.execute();
             } finally {
                 manager.semaphore.release();
             }
         }
 
         /**
          * Cancels the action if not already initialized or waits till completion.
          */
         @Override
         public void close() {
             action.close();
         }
 
         /**
          * Determines if action has been completed.
          *
          * @return true if action is complete.
          */
         @Override
         public boolean isComplete() {
             return action.isComplete();
         }
     }
 
     /**
      * Factory data.
      */
     private static class FactoryData {
         private final String pattern;
         private final boolean append;
         private final boolean bufferedIO;
         private final int bufferSize;
         private final TriggeringPolicy policy;
         private final RolloverStrategy strategy;
         private final String advertiseURI;
         private final Layout<? extends Serializable> layout;
 
         /**
          * Create the data for the factory.
          * @param pattern The pattern.
          * @param append The append flag.
          * @param bufferedIO The bufferedIO flag.
          * @param advertiseURI
          * @param layout The Layout.
          * @param bufferSize the buffer size
          */
         public FactoryData(final String pattern, final boolean append, final boolean bufferedIO,
                 final TriggeringPolicy policy, final RolloverStrategy strategy, final String advertiseURI,
                 final Layout<? extends Serializable> layout, final int bufferSize) {
             this.pattern = pattern;
             this.append = append;
             this.bufferedIO = bufferedIO;
             this.bufferSize = bufferSize;
             this.policy = policy;
             this.strategy = strategy;
             this.advertiseURI = advertiseURI;
             this.layout = layout;
         }
     }
 
     /**
      * Factory to create a RollingFileManager.
      */
     private static class RollingFileManagerFactory implements ManagerFactory<RollingFileManager, FactoryData> {
 
         /**
          * Create the RollingFileManager.
          * @param name The name of the entity to manage.
          * @param data The data required to create the entity.
          * @return a RollingFileManager.
          */
         @Override
         public RollingFileManager createManager(final String name, final FactoryData data) {
             final File file = new File(name);
             final File parent = file.getParentFile();
             if (null != parent && !parent.exists()) {
                 parent.mkdirs();
             }
             try {
                 file.createNewFile();
             } catch (final IOException ioe) {
                 LOGGER.error("Unable to create file " + name, ioe);
                 return null;
             }
             final long size = data.append ? file.length() : 0;
 
             final boolean writeHeader = !data.append || !file.exists();
             OutputStream os;
             try {
                 os = new FileOutputStream(name, data.append);
                 int bufferSize = data.bufferSize;
                 if (data.bufferedIO) {
                     os = new BufferedOutputStream(os, bufferSize);
                 } else {
                     bufferSize = -1; // negative buffer size signals bufferedIO was configured false
                 }
                 final long time = file.lastModified(); // LOG4J2-531 create file first so time has valid value
                 return new RollingFileManager(name, data.pattern, os, data.append, size, time, data.policy,
                     data.strategy, data.advertiseURI, data.layout, bufferSize, writeHeader);
             } catch (final FileNotFoundException ex) {
                 LOGGER.error("FileManager (" + name + ") " + ex);
             }
             return null;
         }
     }
 
 }