/*
 * 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.uima.ducc.agent.launcher;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import org.apache.uima.ducc.common.NodeIdentity;
import org.apache.uima.ducc.common.utils.DuccLogger;
import org.apache.uima.ducc.common.utils.id.DuccId;
import org.apache.uima.ducc.common.utils.id.DuccIdFactory;
import org.apache.uima.ducc.transport.event.common.DuccProcess;
import org.apache.uima.ducc.transport.event.common.IDuccProcess;
import org.apache.uima.ducc.transport.event.common.IDuccProcess.ReasonForStoppingProcess;
import org.apache.uima.ducc.transport.event.common.IProcessState.ProcessState;

public class DefunctProcessDetector implements Runnable {
  ManagedProcess childProcess;

  DuccLogger logger;

  public DefunctProcessDetector(ManagedProcess process, DuccLogger logger) {
    childProcess = process;
    this.logger = logger;
  }

  private boolean isDefunctProcess(String pid) throws Exception {
    boolean zombie = false;
    InputStreamReader in = null;
    String[] command = { "/bin/ps", "-ef", pid };
    try {
      ProcessBuilder pb = new ProcessBuilder();
      pb.command(command);

      pb.redirectErrorStream(true);
      java.lang.Process childProcess = pb.start();
      in = new InputStreamReader(childProcess.getInputStream());
      BufferedReader reader = new BufferedReader(in);
      String line = null;
      while ((line = reader.readLine()) != null) {
        // the ps line will have string <defunct> if the
        // process is a zombie
        zombie = (line.indexOf("defunct") > 0);
        if (zombie) {
          logger.info("DefunctProcessDetector.isDefunctProcess", null,
                  "Process with PID:" + pid + " Is Defunct - OS reports:" + line);
          break;
        }
      }
    } catch (Exception e) {
      throw e;
    } finally {
      if (in != null) {
        try {
          in.close();
        } catch (Exception e) {
        }
      }
    }
    return zombie;
  }

  public void run() {
    try {
      if (isDefunctProcess(childProcess.getPid())) {
        logger.info("DefunctProcessDetector.run()", childProcess.getDuccProcess().getDuccId(),
                "Process with PID:" + childProcess.getPid()
                        + " Is Defunct - Changing State to Stopped");
        childProcess.getDuccProcess().setProcessState(ProcessState.Stopped);
        childProcess.getDuccProcess()
                .setReasonForStoppingProcess(ReasonForStoppingProcess.Defunct.name());
      } else {
        logger.debug("DefunctProcessDetector.run()", childProcess.getDuccProcess().getDuccId(),
                "Process with PID:" + childProcess.getPid() + " Not Defunct");

      }
    } catch (Exception e) {
      logger.error("DefunctProcessDetector.run()", childProcess.getDuccProcess().getDuccId(), e);
    }

  }

  public static void main(String[] args) {
    try {
      DuccLogger logger = new DuccLogger(DefunctProcessDetector.class);
      DuccIdFactory factory = new DuccIdFactory();
      DuccId duccId = factory.next();
      NodeIdentity nid = new NodeIdentity();
      IDuccProcess process = new DuccProcess(duccId, nid);
      ManagedProcess p = new ManagedProcess(process, null);
      process.setProcessState(ProcessState.Initializing);
      process.setPID(args[0]);
      p.setPid(args[0]);
      DefunctProcessDetector detector = new DefunctProcessDetector(p, logger);
      detector.run();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

}