package org.opentrafficsim.road.gtu.lane.tactical.directedlanechange;
   
   import java.util.Collection;
   
   import org.djunits.unit.AccelerationUnit;
   import org.djunits.value.vdouble.scalar.Acceleration;
   import org.djunits.value.vdouble.scalar.DoubleScalar;
   import org.djunits.value.vdouble.scalar.Duration;
   import org.djunits.value.vdouble.scalar.Length;
  import org.djunits.value.vdouble.scalar.Speed;
  import org.opentrafficsim.core.gtu.GTUException;
  import org.opentrafficsim.core.gtu.behavioralcharacteristics.ParameterException;
  import org.opentrafficsim.core.gtu.behavioralcharacteristics.ParameterTypes;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlanException;
  import org.opentrafficsim.core.network.LateralDirectionality;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTU;
  import org.opentrafficsim.road.gtu.lane.perception.LanePerception;
  import org.opentrafficsim.road.gtu.lane.perception.categories.DefaultSimplePerception;
  import org.opentrafficsim.road.gtu.lane.perception.headway.Headway;
  import org.opentrafficsim.road.gtu.lane.tactical.following.DualAccelerationStep;
  import org.opentrafficsim.road.gtu.lane.tactical.following.GTUFollowingModelOld;
  import org.opentrafficsim.road.network.lane.Lane;
  
  /**
   * Common code for a family of lane change models like in M. Treiber and A. Kesting <i>Traffic Flow Dynamics</i>,
   * Springer-Verlag Berlin Heidelberg 2013, pp 239-244.
   * <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/docs/license.html">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision: 1401 $, $LastChangedDate: 2015-09-14 01:33:02 +0200 (Mon, 14 Sep 2015) $, by $Author: averbraeck $,
   *          initial version 4 nov. 2014 <br>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   */
  public abstract class AbstractDirectedLaneChangeModel implements DirectedLaneChangeModel
  {
      /** Attempt to overcome rounding errors. */
      private static Acceleration extraThreshold = new Acceleration(0.000001, AccelerationUnit.SI);
  
      /** the perception. */
      private final LanePerception perception;
  
      /**
       * Construct a DirectedLaneChangeModel.
       * @param perception the perception.
       */
      public AbstractDirectedLaneChangeModel(final LanePerception perception)
      {
          this.perception = perception;
      }
  
      /** {@inheritDoc} */
      @Override
      public final DirectedLaneMovementStep computeLaneChangeAndAcceleration(final LaneBasedGTU gtu,
              final LateralDirectionality direction, final Collection<Headway> sameLaneGTUs,
              final Collection<Headway> otherLaneGTUs, final Length maxDistance, final Speed speedLimit,
              final Acceleration otherLaneRouteIncentive, final Acceleration laneChangeThreshold, final Duration laneChangeTime)
              throws GTUException, ParameterException, OperationalPlanException
      {
          Lane lane = gtu.getReferencePosition().getLane();
          Length longitudinalPosition = gtu.getReferencePosition().getPosition();
          Lane otherLane = getPerception().getPerceptionCategory(DefaultSimplePerception.class).bestAccessibleAdjacentLane(lane,
                  direction, longitudinalPosition);
          GTUFollowingModelOld gtuFollowingModel = (GTUFollowingModelOld) gtu.getTacticalPlanner().getCarFollowingModel();
          if (null == gtuFollowingModel)
          {
              throw new GTUException(gtu + " has null GTUFollowingModel");
          }
          DualAccelerationStep thisLaneAccelerationSteps =
                  gtuFollowingModel.computeDualAccelerationStep(gtu, sameLaneGTUs, maxDistance, speedLimit, laneChangeTime);
          if (thisLaneAccelerationSteps.getLeaderAcceleration().getSI() < -9999)
          {
              System.out.println(gtu + " has a problem: straightAccelerationSteps.getLeaderAcceleration().getSI() < -9999");
          }
          Acceleration straightA = applyDriverPersonality(thisLaneAccelerationSteps).plus(laneChangeThreshold);
          DualAccelerationStep otherLaneAccelerationSteps = null == otherLane ? null
                  : gtuFollowingModel.computeDualAccelerationStep(gtu, otherLaneGTUs, maxDistance, speedLimit, laneChangeTime);
          if (null != otherLaneAccelerationSteps && otherLaneAccelerationSteps.getFollowerAcceleration()
                  .getSI() < -gtu.getBehavioralCharacteristics().getParameter(ParameterTypes.B).getSI())
          {
              otherLane = null; // do not change to the other lane
          }
          Acceleration otherLaneAcceleration = (null == otherLane) ? null : applyDriverPersonality(otherLaneAccelerationSteps);
          if (null == otherLaneAcceleration)
          {
              // No lane change possible; this is definitely the easy case
              return new DirectedLaneMovementStep(thisLaneAccelerationSteps.getLeaderAccelerationStep(), null);
          }
          // A merge to the other lane is possible
          if (DoubleScalar.plus(otherLaneAcceleration, otherLaneRouteIncentive).plus(extraThreshold).ge(straightA))
          {
              // Merge to the other lane
              return new DirectedLaneMovementStep(otherLaneAccelerationSteps.getLeaderAccelerationStep(), direction);
          }
          else
          {
              // Stay in current lane
              return new DirectedLaneMovementStep(thisLaneAccelerationSteps.getLeaderAccelerationStep(), null);
          }
     }
 
     /**
      * Return the weighted acceleration as described by the personality. This incorporates the personality of the driver to the
      * lane change decisions.
      * @param accelerationStep DualAccelerationStep; the DualAccelerationStep that contains the AccelerationStep that the
      *            reference GTU will make and the AccelerationStep that the (new) follower GTU will make
      * @return Acceleration; the acceleration that the personality of the driver uses (in a comparison to a similarly computed
      *         acceleration in the non-, or different-lane-changed state) to decide if a lane change should be performed
      */
     public abstract Acceleration applyDriverPersonality(DualAccelerationStep accelerationStep);
 
     /** {@inheritDoc} */
     @Override
     public final LanePerception getPerception()
     {
         return this.perception;
     }
 }