/*
 * Copyright 2011-2016 UnboundID Corp.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (GPLv2 only)
 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
 * as published by the Free Software Foundation.
 *
 * This program 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 this program; if not, see <http://www.gnu.org/licenses>.
 */

package com.unboundid.scim.tools;

import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.scim.data.BaseResource;
import com.unboundid.scim.sdk.Debug;
import com.unboundid.scim.sdk.Resources;
import com.unboundid.scim.sdk.SCIMEndpoint;
import com.unboundid.scim.sdk.SCIMException;
import com.unboundid.util.FixedRateBarrier;
import com.unboundid.util.ValuePattern;

import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;



/**
 * This class provides a thread that may be used to repeatedly perform queries.
 */
public class QueryRateThread
    extends Thread
{
  // Indicates whether a request has been made to stop running.
  private final AtomicBoolean stopRequested;

  // The counter used to track the number of resources returned.
  private final AtomicLong resourceCounter;

  // The counter used to track the number of errors encountered while querying.
  private final AtomicLong errorCounter;

  // The counter used to track the number of queries performed.
  private final AtomicLong queryCounter;

  // The value that will be updated with total duration of the queries.
  private final AtomicLong queryDurations;

  // The thread that is actually performing the queries.
  private final AtomicReference<Thread> queryThread;

  // The client to use for the queries.
  private SCIMEndpoint<? extends BaseResource> client;

  // The result code for this thread.
  private final AtomicReference<ResultCode> resultCode;

  // The barrier that will be used to coordinate starting among all the threads.
  private final CyclicBarrier startBarrier;

  // The set of requested attributes for query requests.
  private final String[] attributes;

  // The value pattern to use for the filters.
  private final ValuePattern filterPattern;

  // Indicates whether this is a query request or a get request.
  private final boolean isQuery;

  // The barrier to use for controlling the rate of queries.  null if no
  // rate-limiting should be used.
  private final FixedRateBarrier fixedRateBarrier;



  /**
   * Creates a new search rate thread with the provided information.
   *
   * @param  threadNumber     The thread number for this thread.
   * @param  isQuery          Flag indicating whether the request is
   *                          a query or a get.
   * @param  client           The client to use for the queries.
   * @param  filterPattern    The value pattern for the filters.
   * @param  attributes       The set of attributes to return.
   * @param  startBarrier     A barrier used to coordinate starting between all
   *                          of the threads.
   * @param  queryCounter     A value that will be used to keep track of the
   *                          total number of queries performed.
   * @param  resourceCounter  A value that will be used to keep track of the
   *                          total number of resources returned.
   * @param  queryDurations   A value that will be used to keep track of the
   *                          total duration for all queries.
   * @param  errorCounter     A value that will be used to keep track of the
   *                          number of errors encountered while querying.
   * @param  rateBarrier      The barrier to use for controlling the rate of
   *                          queries.  {@code null} if no rate-limiting
   *                          should be used.
   */
  QueryRateThread(final int threadNumber,
                  final boolean isQuery,
                  final SCIMEndpoint<? extends BaseResource> client,
                  final ValuePattern filterPattern,
                  final String[] attributes,
                  final CyclicBarrier startBarrier,
                  final AtomicLong queryCounter,
                  final AtomicLong resourceCounter,
                  final AtomicLong queryDurations,
                  final AtomicLong errorCounter,
                  final FixedRateBarrier rateBarrier)
  {
    setName("QueryRate Thread " + threadNumber);
    setDaemon(true);

    this.client          = client;
    this.isQuery         = isQuery;
    this.filterPattern   = filterPattern;
    this.attributes      = attributes;
    this.queryCounter    = queryCounter;
    this.resourceCounter = resourceCounter;
    this.queryDurations  = queryDurations;
    this.errorCounter    = errorCounter;
    this.startBarrier    = startBarrier;
    fixedRateBarrier     = rateBarrier;

    resultCode    = new AtomicReference<ResultCode>(null);
    queryThread   = new AtomicReference<Thread>(null);
    stopRequested = new AtomicBoolean(false);
  }



  /**
   * Performs all search processing for this thread.
   */
  @Override()
  public void run()
  {
    queryThread.set(currentThread());

    try
    {
      startBarrier.await();
    }
    catch (Exception e)
    {
      Debug.debugException(e);
    }

    while (! stopRequested.get())
    {
      // If we're trying for a specific target rate, then we might need to
      // wait until issuing the next search.
      if (fixedRateBarrier != null)
      {
        fixedRateBarrier.await();
      }

      final String filterValue;
      if (filterPattern != null)
      {
        filterValue = filterPattern.nextValue();
      }
      else
      {
        filterValue = null;
      }

      final long startTime = System.nanoTime();

      try
      {
        if (isQuery)
        {
          final Resources<? extends BaseResource> resources =
            client.query(filterValue, null, null, attributes);
          if (resources != null)
          {
            resourceCounter.addAndGet(resources.getItemsPerPage());
          }
        }
        else
        {
          client.get(filterValue, null, attributes);
          resourceCounter.incrementAndGet();
        }
      }
      catch (SCIMException e)
      {
        Debug.debugException(e);
        errorCounter.incrementAndGet();

        final ResultCode rc = ResultCode.OTHER;
        resultCode.compareAndSet(null, rc);
      }
      catch (RuntimeException e)
      {
        Debug.debugException(e);

        // If we are shutting down then just ignore the error.
        if (stopRequested.get())
        {
          break;
        }

        throw e;
      }

      queryCounter.incrementAndGet();
      queryDurations.addAndGet(System.nanoTime() - startTime);
    }

    queryThread.set(null);
  }



  /**
   * Indicates that this thread should stop running.  It will not wait for the
   * thread to complete before returning.
   */
  void signalShutdown()
  {
    stopRequested.set(true);

    if (fixedRateBarrier != null)
    {
      fixedRateBarrier.shutdownRequested();
    }
  }



  /**
   * Waits for this thread to stop running.
   *
   * @return  A result code that provides information about whether any errors
   *          were encountered during processing.
   */
  ResultCode waitForShutdown()
  {
    final Thread t = queryThread.get();
    if (t != null)
    {
      try
      {
        t.join();
      }
      catch (Exception e)
      {
        Debug.debugException(e);
      }
    }

    resultCode.compareAndSet(null, ResultCode.SUCCESS);
    return resultCode.get();
  }
}