/*
    * Copyright 2012-2017 CodeLibs Project and the Others.
    *
    * Licensed 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.codelibs.fess.thumbnail.impl;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.InputStreamReader;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Timer;
  import java.util.TimerTask;
  
  import javax.annotation.PostConstruct;
  import javax.annotation.Resource;
  import javax.servlet.ServletContext;
  
  import org.apache.commons.io.IOUtils;
  import org.codelibs.core.io.CopyUtil;
  import org.codelibs.core.lang.StringUtil;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class CommandGenerator extends BaseThumbnailGenerator {
      private static final Logger logger = LoggerFactory.getLogger(CommandGenerator.class);
  
      @Resource
      protected ServletContext application;
  
      protected List<String> commandList;
  
      protected long commandTimeout = 30 * 1000L;// 30sec
  
      protected File baseDir;
  
      private volatile Timer destoryTimer;
  
      @PostConstruct
      public void init() {
          if (baseDir == null) {
              baseDir = new File(application.getRealPath("/"));
          }
          destoryTimer = new Timer("CommandGeneratorDestoryTimer-" + System.currentTimeMillis(), true);
      }
  
      @Override
      public void destroy() {
          destoryTimer.cancel();
          destoryTimer = null;
      }
  
      @Override
      public boolean generate(final String thumbnailId, final File outputFile) {
          if (logger.isDebugEnabled()) {
              logger.debug("Generate Thumbnail: " + thumbnailId);
          }
  
          if (outputFile.exists()) {
              if (logger.isDebugEnabled()) {
                  logger.debug("The thumbnail file exists: " + outputFile.getAbsolutePath());
              }
              return true;
          }
  
          final File parentFile = outputFile.getParentFile();
          if (!parentFile.exists()) {
              parentFile.mkdirs();
          }
          if (!parentFile.isDirectory()) {
              logger.warn("Not found: " + parentFile.getAbsolutePath());
              return false;
          }
  
          return process(thumbnailId, responseData -> {
              File tempFile = null;
              try {
                  tempFile = File.createTempFile("thumbnail_", "");
                  CopyUtil.copy(responseData.getResponseBody(), tempFile);
  
                  final String tempPath = tempFile.getAbsolutePath();
                  final String outputPath = outputFile.getAbsolutePath();
                  final List<String> cmdList = new ArrayList<>();
                  for (final String value : commandList) {
                      cmdList.add(expandPath(value.replace("${url}", tempPath).replace("${outputFile}", outputPath)));
                  }
  
                 executeCommand(thumbnailId, cmdList);
 
                 if (outputFile.isFile() && outputFile.length() == 0) {
                     logger.warn("Thumbnail File is empty. ID is " + thumbnailId);
                     if (outputFile.delete()) {
                         logger.info("Deleted: " + outputFile.getAbsolutePath());
                     }
                     updateThumbnailField(thumbnailId, StringUtil.EMPTY);
                     return false;
                 }
 
                 if (logger.isDebugEnabled()) {
                     logger.debug("Thumbnail File: " + outputPath);
                 }
                 return true;
             } catch (final Exception e) {
                 logger.warn("Failed to process ", e);
                 if (tempFile != null && !tempFile.delete()) {
                     logger.debug("Failed to delete " + tempFile.getAbsolutePath());
                 }
                 updateThumbnailField(thumbnailId, StringUtil.EMPTY);
                 return false;
             }
         });
 
     }
 
     protected void executeCommand(final String thumbnailId, final List<String> cmdList) {
         ProcessBuilder pb = null;
         Process p = null;
 
         if (logger.isDebugEnabled()) {
             logger.debug("Thumbnail Command: " + cmdList);
         }
 
         TimerTask task = null;
         try {
             pb = new ProcessBuilder(cmdList);
             pb.directory(baseDir);
             pb.redirectErrorStream(true);
 
             p = pb.start();
 
             task = new ProcessDestroyer(p, cmdList);
             try {
                 destoryTimer.schedule(task, commandTimeout);
 
                 String line;
                 BufferedReader br = null;
                 try {
                     br = new BufferedReader(new InputStreamReader(p.getInputStream(), Charset.defaultCharset()));
                     while ((line = br.readLine()) != null) {
                         if (logger.isDebugEnabled()) {
                             logger.debug(line);
                         }
                     }
                 } finally {
                     IOUtils.closeQuietly(br);
                 }
 
                 p.waitFor();
             } catch (final Exception e) {
                 p.destroy();
             }
         } catch (final Exception e) {
             logger.warn("Failed to generate a thumbnail of " + thumbnailId, e);
         }
         if (task != null) {
             task.cancel();
             task = null;
         }
     }
 
     protected static class ProcessDestroyer extends TimerTask {
 
         private final Process p;
 
         private final List<String> commandList;
 
         protected ProcessDestroyer(final Process p, final List<String> commandList) {
             this.p = p;
             this.commandList = commandList;
         }
 
         @Override
         public void run() {
             logger.warn("CommandGenerator is timed out: " + commandList);
             try {
                 p.destroy();
             } catch (final Exception e) {
                 logger.warn("Failed to stop destroyer.", e);
             }
         }
     }
 
     public void setCommandList(final List<String> commandList) {
         this.commandList = commandList;
     }
 
     public void setCommandTimeout(final long commandTimeout) {
         this.commandTimeout = commandTimeout;
     }
 
     public void setBaseDir(final File baseDir) {
         this.baseDir = baseDir;
     }
 
 }