/*
 * Copyright 2012-2014 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat 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 General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.thread.harvester;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.management.MalformedObjectNameException;

import com.redhat.thermostat.agent.utils.management.MXBeanConnection;
import com.redhat.thermostat.agent.utils.management.MXBeanConnectionPool;
import com.redhat.thermostat.common.Clock;
import com.redhat.thermostat.common.SystemClock;
import com.redhat.thermostat.common.utils.LoggingUtils;
import com.redhat.thermostat.storage.core.WriterID;
import com.redhat.thermostat.thread.dao.ThreadDao;
import com.redhat.thermostat.thread.model.ThreadInfoData;
import com.redhat.thermostat.thread.model.ThreadSummary;
import com.redhat.thermostat.thread.model.VMThreadCapabilities;
import com.redhat.thermostat.thread.model.VmDeadLockData;

@SuppressWarnings("restriction")
class Harvester {
    
    private static final Logger logger = LoggingUtils.getLogger(Harvester.class);
    
    private final ScheduledExecutorService threadPool;
    private final Clock clock;
    
    private final MXBeanConnectionPool connectionPool;
    private final ThreadDao threadDao;
    private final String vmId;
    private final int pid;
    private final WriterID writerId;
    private boolean isConnected;
    private ScheduledFuture<?> harvester;
    private MXBeanConnection connection;
    private ThreadMXBean collectorBean;
    
    Harvester(ThreadDao threadDao, ScheduledExecutorService threadPool,
            String vmId, int pid, MXBeanConnectionPool connectionPool,
            WriterID writerId) {
        this(threadDao, threadPool, new SystemClock(), vmId, pid, connectionPool, writerId);
    }

    Harvester(ThreadDao threadDao, ScheduledExecutorService threadPool,
            Clock clock, String vmId, int pid,
            MXBeanConnectionPool connectionPool, WriterID writerId) {
        this.threadDao = threadDao;
        this.vmId = vmId;
        this.pid = pid;
        this.threadPool = threadPool;
        this.connectionPool = connectionPool;
        this.clock = clock;
        this.writerId = writerId;
    }
    
    synchronized boolean start() {
        if (isConnected) {
            return true;
        }

        if (!connect()) {
            return false;
        }

        harvester = threadPool.scheduleAtFixedRate(new HarvesterAction(), 0, 250, TimeUnit.MILLISECONDS);

        return isConnected;
    }

    private boolean connect() {
        try {
            connection = connectionPool.acquire(pid);
        } catch (Exception ex) {
            logger.log(Level.SEVERE, "can't connect", ex);
            return false;
        }
        
        isConnected = true;
        return true;
    }
    
    boolean isConnected() {
        return isConnected;
    }
    
    synchronized boolean stop() {
        if (!isConnected) {
            return true;
        }
        
        harvester.cancel(false);
        
        return disconnect();
    }
    
    int getPid() {
        return pid;
    }

    private boolean disconnect() {
        if (collectorBean != null) {
            collectorBean = null;
        }
        
        isConnected = false;

        try {
            connectionPool.release(pid, connection);
        } catch (Exception ex) {
            logger.log(Level.SEVERE, "can't disconnect", ex);
            return false;
        }

        return true;
    }
    
    ThreadMXBean getDataCollectorBean(MXBeanConnection connection)
            throws MalformedObjectNameException
    {
        ThreadMXBean bean = null;
        try {
            bean = connection.createProxy(ManagementFactory.THREAD_MXBEAN_NAME,
                                          com.sun.management.ThreadMXBean.class);
        } catch (MalformedObjectNameException ignore) {}

        if (bean == null) {
            bean = connection.createProxy(ManagementFactory.THREAD_MXBEAN_NAME,
                                          ThreadMXBean.class);
        }
        return bean;
    }
    
    synchronized void harvestData() {
      try {
          long timestamp = clock.getRealTimeMillis();

          String wId = writerId.getWriterID();
          ThreadSummary summary = new ThreadSummary(wId);
          
          if (collectorBean == null) {
              collectorBean = getDataCollectorBean(connection);
          }
          
          summary.setCurrentLiveThreads(collectorBean.getThreadCount());
          summary.setCurrentDaemonThreads(collectorBean.getDaemonThreadCount());
          summary.setTimeStamp(timestamp);
          summary.setVmId(vmId);
          threadDao.saveSummary(summary);
          
          long [] ids = collectorBean.getAllThreadIds();
          long[] allocatedBytes = null;
          
          // now the details for the threads
          if (collectorBean instanceof com.sun.management.ThreadMXBean) {
              com.sun.management.ThreadMXBean sunBean = (com.sun.management.ThreadMXBean) collectorBean;
              boolean wasEnabled = false;
              try {
                  if (sunBean.isThreadAllocatedMemorySupported()) {
                      wasEnabled = sunBean.isThreadAllocatedMemoryEnabled();
                      sunBean.setThreadAllocatedMemoryEnabled(true);
                      allocatedBytes = sunBean.getThreadAllocatedBytes(ids);
                      sunBean.setThreadAllocatedMemoryEnabled(wasEnabled);
                  }
              } catch (Exception ignore) {}
          }

          ThreadInfo[] threadInfos = collectorBean.getThreadInfo(ids, true, true);
          
          for (int i = 0; i < ids.length; i++) {
              ThreadInfoData info = new ThreadInfoData(wId);
              ThreadInfo beanInfo = threadInfos[i];

              info.setTimeStamp(timestamp);

              info.setThreadName(beanInfo.getThreadName());
              info.setThreadId(beanInfo.getThreadId());
              info.setState(beanInfo.getThreadState());
              info.setStackTrace(beanInfo.getStackTrace());

              info.setThreadCpuTime(collectorBean.getThreadCpuTime(info.getThreadId()));
              info.setThreadUserTime(collectorBean.getThreadUserTime(info.getThreadId()));
              
              info.setThreadBlockedCount(beanInfo.getBlockedCount());
              info.setThreadWaitCount(beanInfo.getWaitedCount());
              
              if (allocatedBytes != null) {
                  info.setAllocatedBytes(allocatedBytes[i]);
              }

              info.setVmId(vmId);
              threadDao.saveThreadInfo(info);
          }
          
      } catch (MalformedObjectNameException e) {
          e.printStackTrace();
      }
    }
    
    private class HarvesterAction implements Runnable {
        @Override
        public void run() {
            harvestData();
        }
    }
    
    synchronized boolean saveVmCaps() {
        boolean success = false;

        try {
            MXBeanConnection connection = connectionPool.acquire(pid);
            try {

                ThreadMXBean bean = getDataCollectorBean(connection);
                String wId = writerId.getWriterID();
                VMThreadCapabilities caps = new VMThreadCapabilities(wId);

                List<String> features = new ArrayList<>(3);
                if (bean.isThreadCpuTimeSupported())
                    features.add(ThreadDao.CPU_TIME);
                if (bean.isThreadContentionMonitoringSupported())
                    features.add(ThreadDao.CONTENTION_MONITOR);

                if (bean instanceof com.sun.management.ThreadMXBean) {
                    com.sun.management.ThreadMXBean sunBean = (com.sun.management.ThreadMXBean) bean;

                    try {
                        if (sunBean.isThreadAllocatedMemorySupported()) {
                            features.add(ThreadDao.THREAD_ALLOCATED_MEMORY);
                        }
                    } catch (Exception ignore) {
                    }
                    ;
                }
                caps.setSupportedFeaturesList(features.toArray(new String[features.size()]));
                caps.setVmId(vmId);
                threadDao.saveCapabilities(caps);

            } catch (Exception ex) {
                logger.log(Level.SEVERE, "can't get MXBeanConnection connection", ex);
                success = false;
            }
            connectionPool.release(pid, connection);
        } catch (Exception e) {
            logger.log(Level.SEVERE, "can't get MXBeanConnection connection", e);
            success = false;
        }

        return success;
    }

    public boolean saveDeadLockData() {
        boolean disconnectAtEnd = false;
        if (!isConnected) {
            disconnectAtEnd = true;

            connect();
        }

        try {
            if (collectorBean == null) {
                collectorBean = getDataCollectorBean(connection);
            }

            String description = null;
            long timeStamp = clock.getRealTimeMillis();
            long[] ids = collectorBean.findDeadlockedThreads();
            if (ids == null) {
                description = VmDeadLockData.NO_DEADLOCK;
            } else {
                ThreadInfo[] infos = collectorBean.getThreadInfo(ids, true, true);
                StringBuilder descriptionBuilder = new StringBuilder();
                for (ThreadInfo info : infos) {
                    descriptionBuilder.append(info.toString()).append("\n");
                }
                description = descriptionBuilder.toString();
            }
            
            String wId = writerId.getWriterID();
            VmDeadLockData data = new VmDeadLockData(wId);
            data.setTimeStamp(timeStamp);
            data.setVmId(vmId);
            data.setDeadLockDescription(description);

            threadDao.saveDeadLockStatus(data);

        } catch (MalformedObjectNameException e) {
            e.printStackTrace();
        }

        if (disconnectAtEnd) {
            disconnect();
        }

        return true;
    }
    
}