package org.opentrafficsim.road.gtu.lane.tactical.lmrs;
   
   import org.djunits.unit.DimensionlessUnit;
   import org.djunits.value.vdouble.scalar.Acceleration;
   import org.djunits.value.vdouble.scalar.Dimensionless;
   import org.djunits.value.vdouble.scalar.Speed;
   import org.djutils.exceptions.Try;
   import org.opentrafficsim.base.parameters.ParameterException;
   import org.opentrafficsim.base.parameters.ParameterTypeAcceleration;
  import org.opentrafficsim.base.parameters.ParameterTypeSpeed;
  import org.opentrafficsim.base.parameters.ParameterTypes;
  import org.opentrafficsim.base.parameters.Parameters;
  import org.opentrafficsim.core.gtu.perception.EgoPerception;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlanException;
  import org.opentrafficsim.core.network.LateralDirectionality;
  import org.opentrafficsim.road.gtu.lane.perception.LanePerception;
  import org.opentrafficsim.road.gtu.lane.perception.RelativeLane;
  import org.opentrafficsim.road.gtu.lane.perception.categories.InfrastructurePerception;
  import org.opentrafficsim.road.gtu.lane.perception.categories.TrafficPerception;
  import org.opentrafficsim.road.gtu.lane.tactical.following.CarFollowingModel;
  import org.opentrafficsim.road.gtu.lane.tactical.util.lmrs.Desire;
  import org.opentrafficsim.road.gtu.lane.tactical.util.lmrs.LmrsParameters;
  import org.opentrafficsim.road.gtu.lane.tactical.util.lmrs.VoluntaryIncentive;
  
  /**
   * Determines lane change desire for speed. The anticipation speed in the current and adjacent lanes are compared. The larger
   * the difference, the larger the lane change desire. For negative differences, negative desire results. Anticipation speed
   * involves the most critical vehicle considered to be in a lane. Vehicles are more critical if their speed is lower, and if
   * they are closer. The set of vehicles considered to be on a lane includes drivers on adjacent lanes of the considered lane,
   * with a lane change desire towards the considered lane above a certain threshold. If such vehicles have low speeds (i.e.
   * vehicle accelerating to merge), this may result in a courtesy lane change, or in not changing lane out of courtesy from the
   * 2nd lane of the mainline. Vehicles on the current lane of the driver, are not considered on adjacent lanes. This would
   * maintain a large speed difference between the lanes where all drivers do not change lane as they consider leading vehicles to
   * be on the adjacent lane, lowering the anticipation speed on the adjacent lane. The desire for speed is reduced as
   * acceleration is larger, preventing over-assertive lane changes as acceleration out of congestion in the adjacent lane has
   * progressed more.<br>
   * <br>
   * <b>Note:</b> This incentive includes speed, and a form of courtesy. It should therefore not be combined with incentives
   * solely for speed, or solely for courtesy.
   * <p>
   * Copyright (c) 2013-2019 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/docs/current/license.html">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version Apr 13, 2016 <br>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class IncentiveSpeedWithCourtesy implements VoluntaryIncentive
  {
  
      /** Acceleration parameter type. */
      protected static final ParameterTypeAcceleration A = ParameterTypes.A;
  
      /** Anticipation speed difference parameter type. */
      protected static final ParameterTypeSpeed VGAIN = LmrsParameters.VGAIN;
  
      /** Speed threshold below which traffic is considered congested. */
      protected static final ParameterTypeSpeed VCONG = ParameterTypes.VCONG;
  
      /** {@inheritDoc} */
      @Override
      public final Desire determineDesire(final Parameters parameters, final LanePerception perception,
              final CarFollowingModel carFollowingModel, final Desire mandatoryDesire, final Desire voluntaryDesire)
              throws ParameterException, OperationalPlanException
      {
  
          // zero if no lane change is possible
          InfrastructurePerception infra = perception.getPerceptionCategory(InfrastructurePerception.class);
          TrafficPerception traffic = perception.getPerceptionCategory(TrafficPerception.class);
          EgoPerception ego = perception.getPerceptionCategory(EgoPerception.class);
          double leftDist = infra.getLegalLaneChangePossibility(RelativeLane.CURRENT, LateralDirectionality.LEFT).si;
          double rightDist = infra.getLegalLaneChangePossibility(RelativeLane.CURRENT, LateralDirectionality.RIGHT).si;
  
          // gather some info
          Speed vCur = traffic.getSpeed(RelativeLane.CURRENT);
          Speed vGain = parameters.getParameter(VGAIN);
  
          // calculate aGain (default 1; lower as acceleration is higher than 0)
          Dimensionless aGain;
          /*
           * Instead of instantaneous car-following acceleration, use current acceleration; only then is the acceleration factor
           * consistent with possible lane change incentives pertaining to speed (which used to be only vehicles in the original
           * LMRS, but can be any number of reasons here. E.g. traffic lights, conflicts, etc.)
           */
          Acceleration aCur = ego.getAcceleration();
  
          /*
           * The idea to let aCur simply be the current acceleration is wrong; aCur -should- only describe the car-following
           * relation, as this describes a sense of sticking to a lane as the leader is getting away.
           */
          aCur = Try.assign(() -> perception.getGtu().getCarFollowingAcceleration(), "Could not obtain the GTU.");
          if (aCur.si > 0)
          {
              Acceleration a = parameters.getParameter(A);
              aGain = a.minus(aCur).divideBy(a);
          }
          else
          {
              aGain = new Dimensionless(1, DimensionlessUnit.SI);
          }
 
         // left desire
         double dLeft;
         if (leftDist > 0.0 && infra.getCrossSection().contains(RelativeLane.LEFT))
         {
             Speed vLeft = traffic.getSpeed(RelativeLane.LEFT);
             dLeft = aGain.si * (vLeft.si - vCur.si) / vGain.si;
         }
         else
         {
             dLeft = 0.0;
         }
 
         // right desire
         double dRight;
         if (rightDist > 0.0 && infra.getCrossSection().contains(RelativeLane.RIGHT))
         {
             Speed vRight = traffic.getSpeed(RelativeLane.RIGHT);
             if (vCur.si >= parameters.getParameter(VCONG).si)
             {
                 dRight = aGain.si * Math.min(vRight.si - vCur.si, 0) / vGain.si;
             }
             else
             {
                 dRight = aGain.si * (vRight.si - vCur.si) / vGain.si;
             }
         }
         else
         {
             dRight = 0.0;
         }
 
         // return desire
         return new Desire(dLeft, dRight);
     }
 
     /** {@inheritDoc} */
     @Override
     public final String toString()
     {
         return "IncentiveSpeedWithCourtesy";
     }
 
 }