/*
    * 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.File;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.SortedMap;
  import java.util.concurrent.TimeUnit;
  import java.util.zip.Deflater;
  
  import org.apache.logging.log4j.core.Core;
  import org.apache.logging.log4j.core.appender.rolling.action.Action;
  import org.apache.logging.log4j.core.appender.rolling.action.FileRenameAction;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
  import org.apache.logging.log4j.core.config.plugins.PluginElement;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.lookup.StrSubstitutor;
  import org.apache.logging.log4j.core.util.Integers;
  
  /**
   * When rolling over, <code>DefaultRolloverStrategy</code> renames files according to an algorithm as described below.
   *
   * <p>
   * The DefaultRolloverStrategy is a combination of a time-based policy and a fixed-window policy. When the file name
   * pattern contains a date format then the rollover time interval will be used to calculate the time to use in the file
   * pattern. When the file pattern contains an integer replacement token one of the counting techniques will be used.
   * </p>
   * <p>
   * When the ascending attribute is set to true (the default) then the counter will be incremented and the current log
   * file will be renamed to include the counter value. If the counter hits the maximum value then the oldest file, which
   * will have the smallest counter, will be deleted, all other files will be renamed to have their counter decremented
   * and then the current file will be renamed to have the maximum counter value. Note that with this counting strategy
   * specifying a large maximum value may entirely avoid renaming files.
   * </p>
   * <p>
   * When the ascending attribute is false, then the "normal" fixed-window strategy will be used.
   * </p>
   * <p>
   * Let <em>max</em> and <em>min</em> represent the values of respectively the <b>MaxIndex</b> and <b>MinIndex</b>
   * options. Let "foo.log" be the value of the <b>ActiveFile</b> option and "foo.%i.log" the value of
   * <b>FileNamePattern</b>. Then, when rolling over, the file <code>foo.<em>max</em>.log</code> will be deleted, the file
   * <code>foo.<em>max-1</em>.log</code> will be renamed as <code>foo.<em>max</em>.log</code>, the file
   * <code>foo.<em>max-2</em>.log</code> renamed as <code>foo.<em>max-1</em>.log</code>, and so on, the file
   * <code>foo.<em>min+1</em>.log</code> renamed as <code>foo.<em>min+2</em>.log</code>. Lastly, the active file
   * <code>foo.log</code> will be renamed as <code>foo.<em>min</em>.log</code> and a new active file name
   * <code>foo.log</code> will be created.
   * </p>
   * <p>
   * Given that this rollover algorithm requires as many file renaming operations as the window size, large window sizes
   * are discouraged.
   * </p>
   */
  @Plugin(name = "DefaultRolloverStrategy", category = Core.CATEGORY_NAME, printObject = true)
  public class DefaultRolloverStrategy extends AbstractRolloverStrategy {
  
      private static final int MIN_WINDOW_SIZE = 1;
      private static final int DEFAULT_WINDOW_SIZE = 7;
  
      /**
       * Creates the DefaultRolloverStrategy.
       *
       * @param max The maximum number of files to keep.
       * @param min The minimum number of files to keep.
       * @param fileIndex If set to "max" (the default), files with a higher index will be newer than files with a smaller
       *            index. If set to "min", file renaming and the counter will follow the Fixed Window strategy.
       * @param compressionLevelStr The compression level, 0 (less) through 9 (more); applies only to ZIP files.
       * @param customActions custom actions to perform asynchronously after rollover
       * @param stopCustomActionsOnError whether to stop executing asynchronous actions if an error occurs
       * @param config The Configuration.
       * @return A DefaultRolloverStrategy.
       */
      @PluginFactory
      public static DefaultRolloverStrategy createStrategy(
              // @formatter:off
              @PluginAttribute("max") final String max,
             @PluginAttribute("min") final String min,
             @PluginAttribute("fileIndex") final String fileIndex,
             @PluginAttribute("compressionLevel") final String compressionLevelStr,
             @PluginElement("Actions") final Action[] customActions,
             @PluginAttribute(value = "stopCustomActionsOnError", defaultBoolean = true)
                     final boolean stopCustomActionsOnError,
             @PluginConfiguration final Configuration config) {
             // @formatter:on
         int minIndex;
         int maxIndex;
         boolean useMax;
 
         if (fileIndex != null && fileIndex.equalsIgnoreCase("nomax")) {
             minIndex = Integer.MIN_VALUE;
             maxIndex = Integer.MAX_VALUE;
             useMax = false;
         } else {
             useMax = fileIndex == null ? true : fileIndex.equalsIgnoreCase("max");
             minIndex = MIN_WINDOW_SIZE;
             if (min != null) {
                 minIndex = Integer.parseInt(min);
                 if (minIndex < 1) {
                     LOGGER.error("Minimum window size too small. Limited to " + MIN_WINDOW_SIZE);
                     minIndex = MIN_WINDOW_SIZE;
                 }
             }
             maxIndex = DEFAULT_WINDOW_SIZE;
             if (max != null) {
                 maxIndex = Integer.parseInt(max);
                 if (maxIndex < minIndex) {
                     maxIndex = minIndex < DEFAULT_WINDOW_SIZE ? DEFAULT_WINDOW_SIZE : minIndex;
                     LOGGER.error("Maximum window size must be greater than the minimum windows size. Set to " + maxIndex);
                 }
             }
         }
         final int compressionLevel = Integers.parseInt(compressionLevelStr, Deflater.DEFAULT_COMPRESSION);
         return new DefaultRolloverStrategy(minIndex, maxIndex, useMax, compressionLevel, config.getStrSubstitutor(),
                 customActions, stopCustomActionsOnError);
     }
 
     /**
      * Index for oldest retained log file.
      */
     private final int maxIndex;
 
     /**
      * Index for most recent log file.
      */
     private final int minIndex;
     private final boolean useMax;
     private final int compressionLevel;
     private final List<Action> customActions;
     private final boolean stopCustomActionsOnError;
 
     /**
      * Constructs a new instance.
      *
      * @param minIndex The minimum index.
      * @param maxIndex The maximum index.
      * @param customActions custom actions to perform asynchronously after rollover
      * @param stopCustomActionsOnError whether to stop executing asynchronous actions if an error occurs
      */
     protected DefaultRolloverStrategy(final int minIndex, final int maxIndex, final boolean useMax,
             final int compressionLevel, final StrSubstitutor strSubstitutor, final Action[] customActions,
             final boolean stopCustomActionsOnError) {
         super(strSubstitutor);
         this.minIndex = minIndex;
         this.maxIndex = maxIndex;
         this.useMax = useMax;
         this.compressionLevel = compressionLevel;
         this.stopCustomActionsOnError = stopCustomActionsOnError;
         this.customActions = customActions == null ? Collections.<Action> emptyList() : Arrays.asList(customActions);
     }
 
     public int getCompressionLevel() {
         return this.compressionLevel;
     }
 
     public List<Action> getCustomActions() {
         return customActions;
     }
 
     public int getMaxIndex() {
         return this.maxIndex;
     }
 
     public int getMinIndex() {
         return this.minIndex;
     }
 
     public boolean isStopCustomActionsOnError() {
         return stopCustomActionsOnError;
     }
 
     public boolean isUseMax() {
         return useMax;
     }
 
     private int purge(final int lowIndex, final int highIndex, final RollingFileManager manager) {
         return useMax ? purgeAscending(lowIndex, highIndex, manager) : purgeDescending(lowIndex, highIndex, manager);
     }
 
     /**
      * Purges and renames old log files in preparation for rollover. The oldest file will have the smallest index, the
      * newest the highest.
      *
      * @param lowIndex low index. Log file associated with low index will be deleted if needed.
      * @param highIndex high index.
      * @param manager The RollingFileManager
      * @return true if purge was successful and rollover should be attempted.
      */
     private int purgeAscending(final int lowIndex, final int highIndex, final RollingFileManager manager) {
         final SortedMap<Integer, Path> eligibleFiles = getEligibleFiles(manager);
         final int maxFiles = highIndex - lowIndex + 1;
 
         boolean renameFiles = false;
         while (eligibleFiles.size() >= maxFiles) {
             try {
                 LOGGER.debug("Eligible files: {}", eligibleFiles);
                 Integer key = eligibleFiles.firstKey();
                 LOGGER.debug("Deleting {}", eligibleFiles.get(key).toFile().getAbsolutePath());
                 Files.delete(eligibleFiles.get(key));
                 eligibleFiles.remove(key);
                 renameFiles = true;
             } catch (IOException ioe) {
                 LOGGER.error("Unable to delete {}, {}", eligibleFiles.firstKey(), ioe.getMessage(), ioe);
                 break;
             }
         }
         final StringBuilder buf = new StringBuilder();
         if (renameFiles) {
             for (Map.Entry<Integer, Path> entry : eligibleFiles.entrySet()) {
                 buf.setLength(0);
                 // LOG4J2-531: directory scan & rollover must use same format
                 manager.getPatternProcessor().formatFileName(strSubstitutor, buf, entry.getKey() - 1);
                 String currentName = entry.getValue().toFile().getName();
                 String renameTo = buf.toString();
                 int suffixLength = suffixLength(renameTo);
                 if (suffixLength > 0 && suffixLength(currentName) == 0) {
                    renameTo = renameTo.substring(0, renameTo.length() - suffixLength);
                 }
                 Action action = new FileRenameAction(entry.getValue().toFile(), new File(renameTo), true);
                 try {
                     LOGGER.debug("DefaultRolloverStrategy.purgeAscending executing {}", action);
                     if (!action.execute()) {
                         return -1;
                     }
                 } catch (final Exception ex) {
                     LOGGER.warn("Exception during purge in RollingFileAppender", ex);
                     return -1;
                 }
             }
         }
 
         return eligibleFiles.size() > 0 ?
                 (eligibleFiles.lastKey() < highIndex ? eligibleFiles.lastKey() + 1 : highIndex) : lowIndex;
     }
 
     /**
      * Purges and renames old log files in preparation for rollover. The newest file will have the smallest index, the
      * oldest will have the highest.
      *
      * @param lowIndex low index
      * @param highIndex high index. Log file associated with high index will be deleted if needed.
      * @param manager The RollingFileManager
      * @return true if purge was successful and rollover should be attempted.
      */
     private int purgeDescending(final int lowIndex, final int highIndex, final RollingFileManager manager) {
         // Retrieve the files in descending order, so the highest key will be first.
         final SortedMap<Integer, Path> eligibleFiles = getEligibleFiles(manager, false);
         final int maxFiles = highIndex - lowIndex + 1;
 
         while (eligibleFiles.size() >= maxFiles) {
             try {
                 Integer key = eligibleFiles.firstKey();
                 Files.delete(eligibleFiles.get(key));
                 eligibleFiles.remove(key);
             } catch (IOException ioe) {
                 LOGGER.error("Unable to delete {}, {}", eligibleFiles.firstKey(), ioe.getMessage(), ioe);
                 break;
             }
         }
         final StringBuilder buf = new StringBuilder();
         for (Map.Entry<Integer, Path> entry : eligibleFiles.entrySet()) {
             buf.setLength(0);
             // LOG4J2-531: directory scan & rollover must use same format
             manager.getPatternProcessor().formatFileName(strSubstitutor, buf, entry.getKey() + 1);
             String currentName = entry.getValue().toFile().getName();
             String renameTo = buf.toString();
             int suffixLength = suffixLength(renameTo);
             if (suffixLength > 0 && suffixLength(currentName) == 0) {
                 renameTo = renameTo.substring(0, renameTo.length() - suffixLength);
             }
             Action action = new FileRenameAction(entry.getValue().toFile(), new File(renameTo), true);
             try {
                 LOGGER.debug("DefaultRolloverStrategy.purgeDescending executing {}", action);
                 if (!action.execute()) {
                     return -1;
                 }
             } catch (final Exception ex) {
                 LOGGER.warn("Exception during purge in RollingFileAppender", ex);
                 return -1;
             }
         }
 
         return lowIndex;
     }
 
     /**
      * Performs the rollover.
      *
      * @param manager The RollingFileManager name for current active log file.
      * @return A RolloverDescription.
      * @throws SecurityException if an error occurs.
      */
     @Override
     public RolloverDescription rollover(final RollingFileManager manager) throws SecurityException {
         int fileIndex;
         if (minIndex == Integer.MIN_VALUE) {
             final SortedMap<Integer, Path> eligibleFiles = getEligibleFiles(manager);
             fileIndex = eligibleFiles.size() > 0 ? eligibleFiles.lastKey() + 1 : 1;
         } else {
             if (maxIndex < 0) {
                 return null;
             }
             final long startNanos = System.nanoTime();
             fileIndex = purge(minIndex, maxIndex, manager);
             if (fileIndex < 0) {
                 return null;
             }
             if (LOGGER.isTraceEnabled()) {
                 final double durationMillis = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNanos);
                 LOGGER.trace("DefaultRolloverStrategy.purge() took {} milliseconds", durationMillis);
             }
         }
         final StringBuilder buf = new StringBuilder(255);
         manager.getPatternProcessor().formatFileName(strSubstitutor, buf, fileIndex);
         final String currentFileName = manager.getFileName();
 
         String renameTo = buf.toString();
         final String compressedName = renameTo;
         Action compressAction = null;
 
         FileExtension fileExtension = manager.getFileExtension();
         if (fileExtension != null) {
             renameTo = renameTo.substring(0, renameTo.length() - fileExtension.length());
             compressAction = fileExtension.createCompressAction(renameTo, compressedName,
                     true, compressionLevel);
         }
 
         if (currentFileName.equals(renameTo)) {
             LOGGER.warn("Attempt to rename file {} to itself will be ignored", currentFileName);
             return new RolloverDescriptionImpl(currentFileName, false, null, null);
         }
 
         final FileRenameAction renameAction = new FileRenameAction(new File(currentFileName), new File(renameTo),
                     manager.isRenameEmptyFiles());
 
         final Action asyncAction = merge(compressAction, customActions, stopCustomActionsOnError);
         return new RolloverDescriptionImpl(currentFileName, false, renameAction, asyncAction);
     }
 
     @Override
     public String toString() {
         return "DefaultRolloverStrategy(min=" + minIndex + ", max=" + maxIndex + ", useMax=" + useMax + ")";
     }
 
 }