package org.opentrafficsim.kpi.sampling.indicator;
   
   import java.util.HashSet;
   import java.util.Set;
   
   import org.djunits.unit.LengthUnit;
   import org.djunits.value.vdouble.scalar.Duration;
   import org.djunits.value.vdouble.scalar.Length;
   import org.djunits.value.vdouble.scalar.Time;
  import org.opentrafficsim.kpi.interfaces.LinkDataInterface;
  import org.opentrafficsim.kpi.sampling.Query;
  import org.opentrafficsim.kpi.sampling.TrajectoryGroup;
  
  /**
   * Sum of (approximate) link lengths divided by mean speed, divided by link length in km. 
   * <p>
   * Copyright (c) 2013-2016 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version 1 okt. 2016 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class MeanTravelTimePerKm extends AbstractIndicator<Duration>
  {
  
      /** Mean speed indicator. */
      private final MeanSpeed meanSpeed;
  
      /**
       * @param meanSpeed mean speed indicator
       */
      public MeanTravelTimePerKm(final MeanSpeed meanSpeed)
      {
          this.meanSpeed = meanSpeed;
      }
  
      /** {@inheritDoc} */
      @Override
      public final Duration calculate(final Query query, final Time startTime, final Time endTime)
      {
          Length cumulLength = Length.ZERO;
          Set<LinkDataInterface> links = new HashSet<>();
          for (TrajectoryGroup trajectoryGroup : query.getTrajectoryGroups(startTime, endTime))
          {
              if (!links.contains(trajectoryGroup.getLaneDirection().getLaneData().getLinkData()))
              {
                  cumulLength = cumulLength.plus(trajectoryGroup.getLength()); // TODO should be average lane length of link
                  links.add(trajectoryGroup.getLaneDirection().getLaneData().getLinkData());
              }
          }
          return cumulLength.divideBy(this.meanSpeed.getValue(query, startTime, endTime)).divideBy(cumulLength.getInUnit(LengthUnit.KILOMETER));
      }
  
      /** {@inheritDoc} */
      @Override
      @SuppressWarnings("checkstyle:designforextension")
      public String toString()
      {
          return "MeanTravelTime [meanTravelTime=" + this.meanSpeed + " (per km)]";
      }
  
  }