/*
    * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
    *
    * This library is free software; you can redistribute it and/or
    * modify it under the terms of the GNU Lesser General Public
    * License as published by the Free Software Foundation; either
    * version 2.1 of the License, or (at your option) any later version.
    *
    * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
   *
   * Additionally licensed with:
   *
   * Licensed under the Apache Licens e, 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.spf4j.os;
  
  import com.sun.jna.Pointer;
  import com.sun.jna.platform.win32.Kernel32;
  import com.sun.jna.platform.win32.WinNT;
  import java.lang.management.ManagementFactory;
  import java.lang.management.RuntimeMXBean;
  import java.lang.reflect.Field;
  import javax.annotation.Signed;
  import org.spf4j.base.UncheckedExecutionException;
  
  /**
   * PID is exposed in jdk 9... some of this will go away.
   * @author Zoltan Farkas
   */
  public final class ProcessUtil {
  
    private static final int PID = parsePid();
  
    private ProcessUtil() { }
  
    private static int parsePid()  {
      RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();
      String mxBeanName = runtimeMxBean.getName();
      int atIdx = mxBeanName.indexOf('@');
      if (atIdx < 0) {
        return -1;
      } else {
        return Integer.parseInt(mxBeanName.substring(0, atIdx));
      }
    }
  
    /**
     * @return the jvm process ID, -1 if it cannot be figured out.
     */
    @Signed
    public static int getPid() {
      return PID;
    }
  
  
    public static int getPid(final Process p) {
      if (OperatingSystem.isWindows()) {
        return getWindowsPid(p);
      }
      return getUnixPid(p);
    }
  
    private static int getUnixPid(final Process p) {
      try {
        Field pidF = p.getClass().getDeclaredField("pid");
        pidF.setAccessible(true);
        return pidF.getInt(p);
      } catch (IllegalAccessException | NoSuchFieldException | SecurityException ex) {
        throw new UncheckedExecutionException("Cannot get PID for " + p, ex);
      }
    }
  
    private static int getWindowsPid(final Process p) {
      Field f;
      long lHandle;
      try {
        f = p.getClass().getDeclaredField("handle");
        f.setAccessible(true);
        lHandle = f.getLong(p);
      } catch (NoSuchFieldException | SecurityException | IllegalAccessException ex) {
        throw new UncheckedExecutionException("Cannot get PID for " + p, ex);
      }
 
     Kernel32 kernel = Kernel32.INSTANCE;
     WinNT.HANDLE handle = new WinNT.HANDLE();
     handle.setPointer(Pointer.createConstant(lHandle));
     return kernel.GetProcessId(handle);
   }
 
 }