/**
    * Logback: the reliable, generic, fast and flexible logging framework. Copyright (C) 1999-2015, QOS.ch. All rights
    * reserved.
    *
    * This program and the accompanying materials are dual-licensed under either the terms of the Eclipse Public License
    * v1.0 as published by the Eclipse Foundation
    *
    * or (per the licensee's choosing)
    *
   * under the terms of the GNU Lesser General Public License version 2.1 as published by the Free Software Foundation.
   */
  package ch.qos.logback.core.rolling.helper;
  
  import static ch.qos.logback.core.CoreConstants.UNBOUNDED_TOTAL_SIZE_CAP;
  
  import java.io.File;
  import java.time.Instant;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  
  import ch.qos.logback.core.CoreConstants;
  import ch.qos.logback.core.pattern.Converter;
  import ch.qos.logback.core.pattern.LiteralConverter;
  import ch.qos.logback.core.spi.ContextAwareBase;
  import ch.qos.logback.core.util.FileSize;
  
  public class TimeBasedArchiveRemover extends ContextAwareBase implements ArchiveRemover {
  
      static protected final long UNINITIALIZED = -1;
      // aim for 32 days, except in case of hourly rollover, see
      // MAX_VALUE_FOR_INACTIVITY_PERIODS
      static protected final long INACTIVITY_TOLERANCE_IN_MILLIS = 32L * (long) CoreConstants.MILLIS_IN_ONE_DAY;
      static final int MAX_VALUE_FOR_INACTIVITY_PERIODS = 14 * 24; // 14 days in case of hourly rollover
  
      final FileNamePattern fileNamePattern;
      final RollingCalendar rc;
      private int maxHistory = CoreConstants.UNBOUNDED_HISTORY;
      private long totalSizeCap = CoreConstants.UNBOUNDED_TOTAL_SIZE_CAP;
      final boolean parentClean;
      long lastHeartBeat = UNINITIALIZED;
  
      public TimeBasedArchiveRemover(FileNamePattern fileNamePattern, RollingCalendar rc) {
          this.fileNamePattern = fileNamePattern;
          this.rc = rc;
          this.parentClean = computeParentCleaningFlag(fileNamePattern);
      }
  
      int callCount = 0;
  
      public Future<?> cleanAsynchronously(Instant now) {
          ArchiveRemoverRunnable runnable = new ArchiveRemoverRunnable(now);
          ExecutorService alternateExecutorService = context.getAlternateExecutorService();
          Future<?> future = alternateExecutorService.submit(runnable);
          return future;
      }
  
      /**
       * Called from the cleaning thread.
       *
       * @param now
       */
      @Override
      public void clean(Instant now) {
  
          long nowInMillis = now.toEpochMilli();
          // for a live appender periodsElapsed is expected to be 1
          int periodsElapsed = computeElapsedPeriodsSinceLastClean(nowInMillis);
          lastHeartBeat = nowInMillis;
          if (periodsElapsed > 1) {
              addInfo("Multiple periods, i.e. " + periodsElapsed
                      + " periods, seem to have elapsed. This can happen at application start.");
          }
          for (int i = 0; i < periodsElapsed; i++) {
              int offset = getPeriodOffsetForDeletionTarget() - i;
              Instant instantOfPeriodToClean = rc.getEndOfNextNthPeriod(now, offset);
              cleanPeriod(instantOfPeriodToClean);
          }
      }
  
      protected File[] getFilesInPeriod(Instant instantOfPeriodToClean) {
          String filenameToDelete = fileNamePattern.convert(instantOfPeriodToClean);
          File file2Delete = new File(filenameToDelete);
  
          if (fileExistsAndIsFile(file2Delete)) {
              return new File[] { file2Delete };
          } else {
              return new File[0];
          }
      }
  
      private boolean fileExistsAndIsFile(File file2Delete) {
          return file2Delete.exists() && file2Delete.isFile();
      }
  
      public void cleanPeriod(Instant instantOfPeriodToClean) {
          File[] matchingFileArray = getFilesInPeriod(instantOfPeriodToClean);
  
          for (File f : matchingFileArray) {
              addInfo("deleting historically stale " + f);
             checkAndDeleteFile(f);
         }
 
         if (parentClean && matchingFileArray.length > 0) {
             File parentDir = getParentDir(matchingFileArray[0]);
             removeFolderIfEmpty(parentDir);
         }
     }
 
     private boolean checkAndDeleteFile(File f) {
 
         if (f == null) {
             addWarn("Cannot delete empty file");
             return false;
         } else if (!f.exists()) {
             addWarn("Cannot delete non existent file");
             return false;
         }
 
         boolean result = f.delete();
         if (!result) {
             addWarn("Failed to delete file " + f.toString());
         }
         return result;
     }
 
     void capTotalSize(Instant now) {
         long totalSize = 0;
         long totalRemoved = 0;
         int successfulDeletions = 0;
             int failedDeletions = 0;
 
         for (int offset = 0; offset < maxHistory; offset++) {
             Instant instant = rc.getEndOfNextNthPeriod(now, -offset);
             File[] matchingFileArray = getFilesInPeriod(instant);
             descendingSort(matchingFileArray, instant);
             for (File f : matchingFileArray) {
                 long size = f.length();
                 //System.out.println("File: " + f + " size=" + size);
                 totalSize += size;
                 if (totalSize > totalSizeCap) {
                     //addInfo("Deleting [" + f + "]" + " of size " + new FileSize(size) + " on account of totalSizeCap " + totalSizeCap);
                     addInfo("Deleting [" + f + "]" + " of size " + size + " on account of totalSizeCap " + totalSizeCap);
 
                     boolean success = checkAndDeleteFile(f);
 
                     if (success) {
                         successfulDeletions++;
                         totalRemoved += size;
                     } else {
                         failedDeletions++;
                     }
                 }
             }
         }
         if ((successfulDeletions + failedDeletions) == 0) {
             addInfo("No removal attempts were made on account of totalSizeCap="+totalSizeCap);
         } else {
             addInfo("Removed  " + new FileSize(totalRemoved) + " of files in " + successfulDeletions + " files on account of totalSizeCap=" + totalSizeCap);
             if (failedDeletions != 0) {
                 addInfo("There were " + failedDeletions + " failed deletion attempts.");
             }
         }
     }
 
     protected void descendingSort(File[] matchingFileArray, Instant instant) {
         // nothing to do in super class
     }
 
     File getParentDir(File file) {
         File absolute = file.getAbsoluteFile();
         File parentDir = absolute.getParentFile();
         return parentDir;
     }
 
     int computeElapsedPeriodsSinceLastClean(long nowInMillis) {
         long periodsElapsed = 0;
         if (lastHeartBeat == UNINITIALIZED) {
             addInfo("first clean up after appender initialization");
             periodsElapsed = rc.periodBarriersCrossed(nowInMillis, nowInMillis + INACTIVITY_TOLERANCE_IN_MILLIS);
             periodsElapsed = Math.min(periodsElapsed, MAX_VALUE_FOR_INACTIVITY_PERIODS);
         } else {
             periodsElapsed = rc.periodBarriersCrossed(lastHeartBeat, nowInMillis);
             // periodsElapsed of zero is possible for size and time based policies
         }
         return (int) periodsElapsed;
     }
 
     /**
      * Computes whether the fileNamePattern may create sub-folders.
      *
      * @param fileNamePattern
      * @return
      */
     boolean computeParentCleaningFlag(FileNamePattern fileNamePattern) {
         DateTokenConverter<Object> dtc = fileNamePattern.getPrimaryDateTokenConverter();
         // if the date pattern has a /, then we need parent cleaning
         if (dtc.getDatePattern().indexOf('/') != -1) {
             return true;
         }
         // if the literal string after the dtc contains a /, we also
         // need parent cleaning
 
         Converter<Object> p = fileNamePattern.headTokenConverter;
 
         // find the date converter
         while (p != null) {
             if (p instanceof DateTokenConverter) {
                 break;
             }
             p = p.getNext();
         }
 
         while (p != null) {
             if (p instanceof LiteralConverter) {
                 String s = p.convert(null);
                 if (s.indexOf('/') != -1) {
                     return true;
                 }
             }
             p = p.getNext();
         }
 
         // no '/', so we don't need parent cleaning
         return false;
     }
 
     void removeFolderIfEmpty(File dir) {
         removeFolderIfEmpty(dir, 0);
     }
 
     /**
      * Will remove the directory passed as parameter if empty. After that, if the parent is also becomes empty, remove
      * the parent dir as well but at most 3 times.
      *
      * @param dir
      * @param depth
      */
     private void removeFolderIfEmpty(File dir, int depth) {
         // we should never go more than 3 levels higher
         if (depth >= 3) {
             return;
         }
         if (dir.isDirectory() && FileFilterUtil.isEmptyDirectory(dir)) {
             addInfo("deleting folder [" + dir + "]");
             checkAndDeleteFile(dir);
             removeFolderIfEmpty(dir.getParentFile(), depth + 1);
         }
     }
 
     public void setMaxHistory(int maxHistory) {
         this.maxHistory = maxHistory;
     }
 
     protected int getPeriodOffsetForDeletionTarget() {
         return -maxHistory - 1;
     }
 
     public void setTotalSizeCap(long totalSizeCap) {
         this.totalSizeCap = totalSizeCap;
     }
 
     public String toString() {
         return "c.q.l.core.rolling.helper.TimeBasedArchiveRemover";
     }
 
     public class ArchiveRemoverRunnable implements Runnable {
         Instant now;
 
         ArchiveRemoverRunnable(Instant now) {
             this.now = now;
         }
 
         @Override
         public void run() {
             clean(now);
             if (totalSizeCap != UNBOUNDED_TOTAL_SIZE_CAP && totalSizeCap > 0) {
                 capTotalSize(now);
             }
         }
     }
 
 }