package org.opentrafficsim.road.gtu.lane.tactical;
   
   import java.util.ArrayList;
   import java.util.Collection;
   import java.util.HashMap;
   import java.util.List;
   import java.util.Map;
   
   import org.djunits.unit.AccelerationUnit;
  import org.djunits.unit.DurationUnit;
  import org.djunits.unit.LengthUnit;
  import org.djunits.value.StorageType;
  import org.djunits.value.ValueException;
  import org.djunits.value.vdouble.scalar.Acceleration;
  import org.djunits.value.vdouble.scalar.Duration;
  import org.djunits.value.vdouble.scalar.Length;
  import org.djunits.value.vdouble.scalar.Speed;
  import org.djunits.value.vdouble.scalar.Time;
  import org.djunits.value.vdouble.vector.AccelerationVector;
  import org.opentrafficsim.base.parameters.ParameterException;
  import org.opentrafficsim.base.parameters.ParameterTypeLength;
  import org.opentrafficsim.base.parameters.ParameterTypes;
  import org.opentrafficsim.core.geometry.OTSGeometryException;
  import org.opentrafficsim.core.geometry.OTSLine3D;
  import org.opentrafficsim.core.gtu.GTUDirectionality;
  import org.opentrafficsim.core.gtu.GTUException;
  import org.opentrafficsim.core.gtu.GTUType;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlan;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlan.Segment;
  import org.opentrafficsim.core.gtu.plan.operational.OperationalPlanException;
  import org.opentrafficsim.core.network.LateralDirectionality;
  import org.opentrafficsim.core.network.Link;
  import org.opentrafficsim.core.network.NetworkException;
  import org.opentrafficsim.core.network.Node;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTU;
  import org.opentrafficsim.road.gtu.lane.perception.CategoricalLanePerception;
  import org.opentrafficsim.road.gtu.lane.perception.LanePerception;
  import org.opentrafficsim.road.gtu.lane.perception.categories.DefaultSimplePerception;
  import org.opentrafficsim.road.gtu.lane.perception.categories.DirectDefaultSimplePerception;
  import org.opentrafficsim.road.gtu.lane.perception.headway.Headway;
  import org.opentrafficsim.road.gtu.lane.perception.headway.HeadwayTrafficLight;
  import org.opentrafficsim.road.gtu.lane.tactical.following.GTUFollowingModelOld;
  import org.opentrafficsim.road.gtu.lane.tactical.lanechangemobil.LaneChangeModel;
  import org.opentrafficsim.road.gtu.lane.tactical.lanechangemobil.LaneMovementStep;
  import org.opentrafficsim.road.network.lane.CrossSectionElement;
  import org.opentrafficsim.road.network.lane.CrossSectionLink;
  import org.opentrafficsim.road.network.lane.DirectedLanePosition;
  import org.opentrafficsim.road.network.lane.Lane;
  import org.opentrafficsim.road.network.lane.object.sensor.SingleSensor;
  import org.opentrafficsim.road.network.lane.object.sensor.SinkSensor;
  
  import nl.tudelft.simulation.language.d3.DirectedPoint;
  
  /**
   * Lane-based tactical planner that implements car following and lane change behavior. This lane-based tactical planner makes
   * decisions based on headway (GTU following model) and lane change (Lane Change model), and will generate an operational plan
   * for the GTU. It can ask the strategic planner for assistance on the route to take when the network splits.
   * <p>
   * Copyright (c) 2013-2018 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>
   * $LastChangedDate: 2015-07-24 02:58:59 +0200 (Fri, 24 Jul 2015) $, @version $Revision: 1147 $, by $Author: averbraeck $,
   * initial version Nov 25, 2015 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   */
  public class LaneBasedCFLCTacticalPlanner extends AbstractLaneBasedTacticalPlanner
  {
      /** */
      private static final long serialVersionUID = 20151125L;
  
      /** Look back parameter type. */
      protected static final ParameterTypeLength LOOKBACKOLD = ParameterTypes.LOOKBACKOLD;
  
      /** Standard incentive to stay in the current lane. */
      private static final Acceleration STAYINCURRENTLANEINCENTIVE = new Acceleration(0.1, AccelerationUnit.METER_PER_SECOND_2);
  
      /** Standard incentive to stay in the current lane. */
      private static final Acceleration PREFERREDLANEINCENTIVE = new Acceleration(0.3, AccelerationUnit.METER_PER_SECOND_2);
  
      /** Standard incentive to stay in the current lane. */
      private static final Acceleration NONPREFERREDLANEINCENTIVE = new Acceleration(-0.3, AccelerationUnit.METER_PER_SECOND_2);
  
      /** Return value of suitability when no lane change is required within the time horizon. */
      public static final Length NOLANECHANGENEEDED = new Length(Double.MAX_VALUE, LengthUnit.SI);
  
      /** Return value of suitability when a lane change is required <i>right now</i>. */
      public static final Length GETOFFTHISLANENOW = Length.ZERO;
  
      /** Standard time horizon for route choices. */
      private static final Duration TIMEHORIZON = new Duration(90, DurationUnit.SECOND);
  
      /** Lane change model for this tactical planner. */
      private LaneChangeModel laneChangeModel;
  
      /**
       * Instantiated a tactical planner with GTU following and lane change behavior.
       * @param carFollowingModel Car-following model.
       * @param laneChangeModel Lane change model.
      * @param gtu GTU
      */
     public LaneBasedCFLCTacticalPlanner(final GTUFollowingModelOld carFollowingModel, final LaneChangeModel laneChangeModel,
             final LaneBasedGTU gtu)
     {
         super(carFollowingModel, gtu, new CategoricalLanePerception(gtu));
         this.laneChangeModel = laneChangeModel;
         getPerception().addPerceptionCategory(new DirectDefaultSimplePerception(getPerception()));
     }
 
     /** {@inheritDoc} */
     @Override
     public final OperationalPlan generateOperationalPlan(final Time startTime, final DirectedPoint locationAtStartTime)
             throws OperationalPlanException, NetworkException, GTUException, ParameterException
     {
         try
         {
             // define some basic variables
             LaneBasedGTU laneBasedGTU = getGtu();
             LanePerception perception = getPerception();
 
             // if the GTU's maximum speed is zero (block), generate a stand still plan for one second
             if (laneBasedGTU.getMaximumSpeed().si < OperationalPlan.DRIFTING_SPEED_SI)
             {
                 return new OperationalPlan(getGtu(), locationAtStartTime, startTime, new Duration(1.0, DurationUnit.SECOND));
             }
 
             // perceive every time step... This is the 'classical' way of tactical planning.
             // NOTE: delete this if perception takes place independent of the tactical planning (different frequency)
             perception.perceive();
 
             Length maximumForwardHeadway = laneBasedGTU.getParameters().getParameter(LOOKAHEAD);
             DefaultSimplePerception simplePerception = perception.getPerceptionCategory(DefaultSimplePerception.class);
             Speed speedLimit = simplePerception.getSpeedLimit();
 
             // look at the conditions for headway on the current lane
             Headway sameLaneLeader = simplePerception.getForwardHeadwayGTU();
             // TODO how to handle objects on this lane or another lane???
             Headway sameLaneFollower = simplePerception.getBackwardHeadway();
             Collection<Headway> sameLaneTraffic = new ArrayList<>();
             if (sameLaneLeader.getObjectType().isGtu())
             {
                 sameLaneTraffic.add(sameLaneLeader);
             }
             if (sameLaneFollower.getObjectType().isGtu())
             {
                 sameLaneTraffic.add(sameLaneFollower);
             }
 
             // Are we in the right lane for the route?
             LanePathInfo lanePathInfo = buildLanePathInfo(laneBasedGTU, maximumForwardHeadway);
 
             // TODO these two info's are not used
             NextSplitInfo nextSplitInfo = determineNextSplit(laneBasedGTU, maximumForwardHeadway);
             boolean currentLaneFine = nextSplitInfo.getCorrectCurrentLanes().contains(lanePathInfo.getReferenceLane());
 
             // calculate the lane change step
             // TODO skip if:
             // - we are in the right lane and drive at max speed or we accelerate maximally
             // - there are no other lanes
             Collection<Headway> leftLaneTraffic = simplePerception.getNeighboringHeadwaysLeft();
             Collection<Headway> rightLaneTraffic = simplePerception.getNeighboringHeadwaysRight();
 
             // FIXME: whether we drive on the right should be stored in some central place.
             final LateralDirectionality preferred = LateralDirectionality.RIGHT;
             final Acceleration defaultLeftLaneIncentive =
                     preferred.isLeft() ? PREFERREDLANEINCENTIVE : NONPREFERREDLANEINCENTIVE;
             final Acceleration defaultRightLaneIncentive =
                     preferred.isRight() ? PREFERREDLANEINCENTIVE : NONPREFERREDLANEINCENTIVE;
 
             AccelerationVector defaultLaneIncentives =
                     new AccelerationVector(new double[] { defaultLeftLaneIncentive.getSI(), STAYINCURRENTLANEINCENTIVE.getSI(),
                             defaultRightLaneIncentive.getSI() }, AccelerationUnit.SI, StorageType.DENSE);
             AccelerationVector laneIncentives = laneIncentives(laneBasedGTU, defaultLaneIncentives);
             LaneMovementStep lcmr = this.laneChangeModel.computeLaneChangeAndAcceleration(laneBasedGTU, sameLaneTraffic,
                     rightLaneTraffic, leftLaneTraffic, speedLimit,
                     new Acceleration(laneIncentives.get(preferred.isRight() ? 2 : 0)), new Acceleration(laneIncentives.get(1)),
                     new Acceleration(laneIncentives.get(preferred.isRight() ? 0 : 2)));
             Duration duration = lcmr.getGfmr().getValidUntil().minus(getGtu().getSimulator().getSimulatorTime());
             if (lcmr.getLaneChangeDirection() != null)
             {
                 laneBasedGTU.changeLaneInstantaneously(lcmr.getLaneChangeDirection());
 
                 // create the path to drive in this timestep.
                 lanePathInfo = buildLanePathInfo(laneBasedGTU, maximumForwardHeadway);
             }
 
             // incorporate traffic light
             Headway object = simplePerception.getForwardHeadwayObject();
             Acceleration a = lcmr.getGfmr().getAcceleration();
             if (object instanceof HeadwayTrafficLight)
             {
                 // if it was perceived, it was red, or yellow and judged as requiring to stop
                 a = Acceleration.min(a, ((GTUFollowingModelOld) getCarFollowingModel()).computeAcceleration(getGtu().getSpeed(),
                         getGtu().getMaximumSpeed(), Speed.ZERO, object.getDistance(), speedLimit));
             }
 
             // incorporate dead-end/split
             Length dist = lanePathInfo.getPath().getLength().minus(getGtu().getFront().getDx());
             a = Acceleration.min(a, ((GTUFollowingModelOld) getCarFollowingModel()).computeAcceleration(getGtu().getSpeed(),
                     getGtu().getMaximumSpeed(), Speed.ZERO, dist, speedLimit));
 
             // build a list of lanes forward, with a maximum headway.
             OTSLine3D path = lanePathInfo.getPath();
             if (a.si < 1E-6 && laneBasedGTU.getSpeed().si < OperationalPlan.DRIFTING_SPEED_SI)
             {
                 try
                 {
                     return new OperationalPlan(getGtu(), path.getLocationFraction(0.0), startTime, duration);
                 }
                 catch (OTSGeometryException exception)
                 {
                     // should not happen as 0.0 should be accepted
                     throw new RuntimeException(exception);
                 }
             }
             List<Segment> operationalPlanSegmentList = new ArrayList<>();
 
             if (a.si == 0.0)
             {
                 Segment segment = new OperationalPlan.SpeedSegment(duration);
                 operationalPlanSegmentList.add(segment);
             }
             else
             {
                 Segment segment = new OperationalPlan.AccelerationSegment(duration, a);
                 operationalPlanSegmentList.add(segment);
             }
             OperationalPlan op =
                     new OperationalPlan(getGtu(), path, startTime, getGtu().getSpeed(), operationalPlanSegmentList);
             return op;
         }
         catch (ValueException exception)
         {
             throw new GTUException(exception);
         }
     }
 
     /**
      * TODO: move laneIncentives to LanePerception? Figure out if the default lane incentives are OK, or override them with
      * values that should keep this GTU on the intended route.
      * @param gtu the GTU for which to calculate the incentives
      * @param defaultLaneIncentives AccelerationVector; the three lane incentives for the next left adjacent lane, the current
      *            lane and the next right adjacent lane
      * @return AccelerationVector; the (possibly adjusted) lane incentives
      * @throws NetworkException on network inconsistency
      * @throws ValueException cannot happen
      * @throws GTUException when the position of the GTU cannot be correctly determined
      * @throws OperationalPlanException if DefaultAlexander perception category is not present
      */
     private AccelerationVector laneIncentives(final LaneBasedGTU gtu, final AccelerationVector defaultLaneIncentives)
             throws NetworkException, ValueException, GTUException, OperationalPlanException
     {
         Length leftSuitability = suitability(gtu, LateralDirectionality.LEFT);
         Length currentSuitability = suitability(gtu, null);
         Length rightSuitability = suitability(gtu, LateralDirectionality.RIGHT);
         if (leftSuitability == NOLANECHANGENEEDED && currentSuitability == NOLANECHANGENEEDED
                 && rightSuitability == NOLANECHANGENEEDED)
         {
             return checkLaneDrops(gtu, defaultLaneIncentives);
         }
         if ((leftSuitability == NOLANECHANGENEEDED || leftSuitability == GETOFFTHISLANENOW)
                 && currentSuitability == NOLANECHANGENEEDED
                 && (rightSuitability == NOLANECHANGENEEDED || rightSuitability == GETOFFTHISLANENOW))
         {
             return checkLaneDrops(gtu,
                     new AccelerationVector(new double[] { acceleration(gtu, leftSuitability),
                             defaultLaneIncentives.get(1).getSI(), acceleration(gtu, rightSuitability) }, AccelerationUnit.SI,
                             StorageType.DENSE));
         }
         if (currentSuitability == NOLANECHANGENEEDED)
         {
             return new AccelerationVector(new double[] { acceleration(gtu, leftSuitability),
                     defaultLaneIncentives.get(1).getSI(), acceleration(gtu, rightSuitability) }, AccelerationUnit.SI,
                     StorageType.DENSE);
         }
         return new AccelerationVector(new double[] { acceleration(gtu, leftSuitability), acceleration(gtu, currentSuitability),
                 acceleration(gtu, rightSuitability) }, AccelerationUnit.SI, StorageType.DENSE);
     }
 
     /**
      * Figure out if the default lane incentives are OK, or override them with values that should keep this GTU from running out
      * of road at an upcoming lane drop.
      * @param gtu the GTU for which to check the lane drops
      * @param defaultLaneIncentives DoubleVector.Rel.Dense&lt;AccelerationUnit&gt; the three lane incentives for the next left
      *            adjacent lane, the current lane and the next right adjacent lane
      * @return DoubleVector.Rel.Dense&lt;AccelerationUnit&gt;; the (possibly adjusted) lane incentives
      * @throws NetworkException on network inconsistency
      * @throws ValueException cannot happen
      * @throws GTUException when the positions of the GTU cannot be determined
      * @throws OperationalPlanException if DefaultAlexander perception category is not present
      */
     private AccelerationVector checkLaneDrops(final LaneBasedGTU gtu, final AccelerationVector defaultLaneIncentives)
             throws NetworkException, ValueException, GTUException, OperationalPlanException
     {
         // FIXME: these comparisons to -10 is ridiculous.
         Length leftSuitability = Double.isNaN(defaultLaneIncentives.get(0).si) || defaultLaneIncentives.get(0).si < -10
                 ? GETOFFTHISLANENOW : laneDrop(gtu, LateralDirectionality.LEFT);
         Length currentSuitability = laneDrop(gtu, null);
         Length rightSuitability = Double.isNaN(defaultLaneIncentives.get(2).si) || defaultLaneIncentives.get(2).si < -10
                 ? GETOFFTHISLANENOW : laneDrop(gtu, LateralDirectionality.RIGHT);
         // @formatter:off
         if ((leftSuitability == NOLANECHANGENEEDED || leftSuitability == GETOFFTHISLANENOW)
                 && currentSuitability == NOLANECHANGENEEDED
                 && (rightSuitability == NOLANECHANGENEEDED || rightSuitability == GETOFFTHISLANENOW))
         {
             return defaultLaneIncentives;
         }
         // @formatter:on
         if (currentSuitability == NOLANECHANGENEEDED)
         {
             return new AccelerationVector(new double[] { acceleration(gtu, leftSuitability),
                     defaultLaneIncentives.get(1).getSI(), acceleration(gtu, rightSuitability) }, AccelerationUnit.SI,
                     StorageType.DENSE);
         }
         if (currentSuitability.le(leftSuitability))
         {
             return new AccelerationVector(new double[] { PREFERREDLANEINCENTIVE.getSI(), NONPREFERREDLANEINCENTIVE.getSI(),
                     GETOFFTHISLANENOW.getSI() }, AccelerationUnit.SI, StorageType.DENSE);
         }
         if (currentSuitability.le(rightSuitability))
         {
             return new AccelerationVector(new double[] { GETOFFTHISLANENOW.getSI(), NONPREFERREDLANEINCENTIVE.getSI(),
                     PREFERREDLANEINCENTIVE.getSI() }, AccelerationUnit.SI, StorageType.DENSE);
         }
         return new AccelerationVector(new double[] { acceleration(gtu, leftSuitability), acceleration(gtu, currentSuitability),
                 acceleration(gtu, rightSuitability) }, AccelerationUnit.SI, StorageType.DENSE);
     }
 
     /**
      * Return the distance until the next lane drop in the specified (nearby) lane.
      * @param gtu the GTU to determine the next lane drop for
      * @param direction LateralDirectionality; one of the values <cite>LateralDirectionality.LEFT</cite> (use the left-adjacent
      *            lane), or <cite>LateralDirectionality.RIGHT</cite> (use the right-adjacent lane), or <cite>null</cite> (use
      *            the current lane)
      * @return DoubleScalar.Rel&lt;LengthUnit&gt;; distance until the next lane drop if it occurs within the TIMEHORIZON, or
      *         LaneBasedRouteNavigator.NOLANECHANGENEEDED if this lane can be followed until the next split junction or until
      *         beyond the TIMEHORIZON
      * @throws NetworkException on network inconsistency
      * @throws GTUException when the positions of the GTU cannot be determined
      * @throws OperationalPlanException if DefaultAlexander perception category is not present
      */
     private Length laneDrop(final LaneBasedGTU gtu, final LateralDirectionality direction)
             throws NetworkException, GTUException, OperationalPlanException
     {
         DirectedLanePosition dlp = gtu.getReferencePosition();
         Lane lane = dlp.getLane();
         Length longitudinalPosition = dlp.getPosition();
         if (null != direction)
         {
             lane = getPerception().getPerceptionCategory(DefaultSimplePerception.class).bestAccessibleAdjacentLane(lane,
                     direction, longitudinalPosition);
         }
         if (null == lane)
         {
             return GETOFFTHISLANENOW;
         }
         double remainingLength = lane.getLength().getSI() - longitudinalPosition.getSI();
         double remainingTimeSI = TIMEHORIZON.getSI() - remainingLength / lane.getSpeedLimit(gtu.getGTUType()).getSI();
         while (remainingTimeSI >= 0)
         {
             for (SingleSensor s : lane.getSensors())
             {
                 if (s instanceof SinkSensor)
                 {
                     return NOLANECHANGENEEDED;
                 }
             }
             int branching = lane.nextLanes(gtu.getGTUType()).size();
             if (branching == 0)
             {
                 return new Length(remainingLength, LengthUnit.SI);
             }
             if (branching > 1)
             {
                 return NOLANECHANGENEEDED;
             }
             lane = lane.nextLanes(gtu.getGTUType()).keySet().iterator().next();
             remainingTimeSI -= lane.getLength().getSI() / lane.getSpeedLimit(gtu.getGTUType()).getSI();
             remainingLength += lane.getLength().getSI();
         }
         return NOLANECHANGENEEDED;
     }
 
     /**
      * TODO: move suitability to LanePerception? Return the suitability for the current lane, left adjacent lane or right
      * adjacent lane.
      * @param gtu the GTU for which to calculate the incentives
      * @param direction LateralDirectionality; one of the values <cite>null</cite>, <cite>LateralDirectionality.LEFT</cite>, or
      *            <cite>LateralDirectionality.RIGHT</cite>
      * @return DoubleScalar.Rel&lt;LengthUnit&gt;; the suitability of the lane for reaching the (next) destination
      * @throws NetworkException on network inconsistency
      * @throws GTUException when position cannot be determined
      * @throws OperationalPlanException if DefaultAlexander perception category is not present
      */
     private Length suitability(final LaneBasedGTU gtu, final LateralDirectionality direction)
             throws NetworkException, GTUException, OperationalPlanException
     {
         DirectedLanePosition dlp = gtu.getReferencePosition();
         Lane lane = dlp.getLane();
         Length longitudinalPosition = dlp.getPosition().plus(gtu.getFront().getDx());
         if (null != direction)
         {
             lane = getPerception().getPerceptionCategory(DefaultSimplePerception.class).bestAccessibleAdjacentLane(lane,
                     direction, longitudinalPosition);
         }
         if (null == lane)
         {
             return GETOFFTHISLANENOW;
         }
         try
         {
             return suitability(lane, longitudinalPosition, gtu, TIMEHORIZON);
             // return suitability(lane, lane.getLength().minus(longitudinalPosition), gtu, TIMEHORIZON);
         }
         catch (NetworkException ne)
         {
             System.err.println(gtu + " has a route problem in suitability: " + ne.getMessage());
             return NOLANECHANGENEEDED;
         }
     }
 
     /**
      * Compute deceleration needed to stop at a specified distance.
      * @param gtu the GTU for which to calculate the acceleration to come to a full stop at the distance
      * @param stopDistance DoubleScalar.Rel&lt;LengthUnit&gt;; the distance
      * @return double; the acceleration (deceleration) needed to stop at the specified distance in m/s/s
      */
     private double acceleration(final LaneBasedGTU gtu, final Length stopDistance)
     {
         // What is the deceleration that will bring this GTU to a stop at exactly the suitability distance?
         // Answer: a = -v^2 / 2 / suitabilityDistance
         double v = gtu.getSpeed().getSI();
         double a = -v * v / 2 / stopDistance.getSI();
         return a;
     }
 
     /**
      * Determine the suitability of being at a particular longitudinal position in a particular Lane for following this Route.
      * <br>
      * TODO this code assumes GTUDirectionality.DIR_PLUS on all lanes of interest
      * @param lane Lane; the lane to consider
      * @param longitudinalPosition DoubleScalar.Rel&lt;LengthUnit&gt;; the longitudinal position in the lane
      * @param gtu GTU; the GTU (used to check lane compatibility of lanes, and current lane the GTU is on)
      * @param timeHorizon DoubleScalar.Rel&lt;TimeUnit&gt;; the maximum time that a driver may want to look ahead
      * @return DoubleScalar.Rel&lt;LengthUnit&gt;; a value that indicates within what distance the GTU should try to vacate this
      *         lane.
      * @throws NetworkException on network inconsistency, or when the continuation Link at a branch cannot be determined
      */
     private Length suitability(final Lane lane, final Length longitudinalPosition, final LaneBasedGTU gtu,
             final Duration timeHorizon) throws NetworkException
     {
         double remainingDistance = lane.getLength().getSI() - longitudinalPosition.getSI();
         double spareTime = timeHorizon.getSI() - remainingDistance / lane.getSpeedLimit(gtu.getGTUType()).getSI();
         // Find the first upcoming Node where there is a branch
         Node nextNode = lane.getParentLink().getEndNode();
         Link lastLink = lane.getParentLink();
         Node nextSplitNode = null;
         Lane currentLane = lane;
         CrossSectionLink linkBeforeBranch = lane.getParentLink();
         while (null != nextNode)
         {
             if (spareTime <= 0)
             {
                 return NOLANECHANGENEEDED; // It is not yet time to worry; this lane will do as well as any other
             }
             int laneCount = countCompatibleLanes(linkBeforeBranch, gtu.getGTUType(), GTUDirectionality.DIR_PLUS);
             if (0 == laneCount)
             {
                 throw new NetworkException("No compatible Lanes on Link " + linkBeforeBranch);
             }
             if (1 == laneCount)
             {
                 return NOLANECHANGENEEDED; // Only one compatible lane available; we'll get there "automatically";
                 // i.e. without influence from the Route
             }
             int branching = nextNode.getLinks().size();
             if (branching > 2)
             { // Found a split
                 nextSplitNode = nextNode;
                 break;
             }
             else if (1 == branching)
             {
                 return NOLANECHANGENEEDED; // dead end; no more choices to make
             }
             else
             { // Look beyond this nextNode
                 Link nextLink = gtu.getStrategicalPlanner().nextLinkDirection(nextNode, lastLink, gtu.getGTUType()).getLink();
                 if (nextLink instanceof CrossSectionLink)
                 {
                     GTUDirectionality drivingDirection =
                             nextNode.equals(nextLink.getStartNode()) ? GTUDirectionality.DIR_PLUS : GTUDirectionality.DIR_MINUS;
                     nextNode = nextLink.getEndNode();
                     // Oops: wrong code added the length of linkBeforeBranch in stead of length of nextLink
                     remainingDistance += nextLink.getLength().getSI();
                     linkBeforeBranch = (CrossSectionLink) nextLink;
                     // Figure out the new currentLane
                     if (currentLane.nextLanes(gtu.getGTUType()).size() == 0)
                     {
                         // Lane drop; our lane disappears. This is a compulsory lane change; which is not controlled
                         // by the Route. Perform the forced lane change.
                         if (currentLane.accessibleAdjacentLanesLegal(LateralDirectionality.RIGHT, gtu.getGTUType(), drivingDirection)
                                 .size() > 0)
                         {
                             for (Lane adjacentLane : currentLane.accessibleAdjacentLanesLegal(LateralDirectionality.RIGHT,
                                     gtu.getGTUType(), drivingDirection))
                             {
                                 if (adjacentLane.nextLanes(gtu.getGTUType()).size() > 0)
                                 {
                                     currentLane = adjacentLane;
                                     break;
                                 }
                                 // If there are several adjacent lanes that have non empty nextLanes, we simple take the
                                 // first in the set
                             }
                         }
                         for (Lane adjacentLane : currentLane.accessibleAdjacentLanesLegal(LateralDirectionality.LEFT,
                                 gtu.getGTUType(), drivingDirection))
                         {
                             if (adjacentLane.nextLanes(gtu.getGTUType()).size() > 0)
                             {
                                 currentLane = adjacentLane;
                                 break;
                             }
                             // If there are several adjacent lanes that have non empty nextLanes, we simple take the
                             // first in the set
                         }
                         if (currentLane.nextLanes(gtu.getGTUType()).size() == 0)
                         {
                             throw new NetworkException(
                                     "Lane ends and there is not a compatible adjacent lane that does " + "not end");
                         }
                     }
                     // Any compulsory lane change(s) have been performed and there is guaranteed a compatible next lane.
                     for (Lane nextLane : currentLane.nextLanes(gtu.getGTUType()).keySet())
                     {
                         if (nextLane.getLaneType().getDirectionality(gtu.getGTUType()).getDirectionalities()
                                 .contains(drivingDirection))
                         {
                             currentLane = currentLane.nextLanes(gtu.getGTUType()).keySet().iterator().next();
                             break;
                         }
                     }
                     spareTime -= currentLane.getLength().getSI() / currentLane.getSpeedLimit(gtu.getGTUType()).getSI();
                 }
                 else
                 {
                     // There is a non-CrossSectionLink on the path to the next branch. A non-CrossSectionLink does not
                     // have identifiable Lanes, therefore we can't aim for a particular Lane
                     return NOLANECHANGENEEDED; // Any Lane will do equally well
                 }
                 lastLink = nextLink;
             }
         }
         if (null == nextNode)
         {
             throw new NetworkException("Cannot find the next branch or sink node");
         }
         // We have now found the first upcoming branching Node
         // Which continuing link is the one we need?
         Map<Lane, Length> suitabilityOfLanesBeforeBranch = new HashMap<>();
         Link linkAfterBranch =
                 gtu.getStrategicalPlanner().nextLinkDirection(nextSplitNode, lastLink, gtu.getGTUType()).getLink();
         GTUDirectionality drivingDirectionOnNextLane =
                 linkAfterBranch.getStartNode().equals(nextSplitNode) ? GTUDirectionality.DIR_PLUS : GTUDirectionality.DIR_MINUS;
         for (CrossSectionElement cse : linkBeforeBranch.getCrossSectionElementList())
         {
             if (cse instanceof Lane)
             {
                 Lane l = (Lane) cse;
                 if (l.getLaneType().getDirectionality(gtu.getGTUType()).getDirectionalities()
                         .contains(GTUDirectionality.DIR_PLUS))
                 {
                     for (Lane connectingLane : l.nextLanes(gtu.getGTUType()).keySet())
                     {
                         if (connectingLane.getParentLink() == linkAfterBranch
                                 && connectingLane.getLaneType().isCompatible(gtu.getGTUType(), drivingDirectionOnNextLane))
                         {
                             Length currentValue = suitabilityOfLanesBeforeBranch.get(l);
                             // Use recursion to find out HOW suitable this continuation lane is, but don't revert back
                             // to the maximum time horizon (or we could end up in infinite recursion when there are
                             // loops in the network).
                             Length value = suitability(connectingLane, new Length(0, LengthUnit.SI), gtu,
                                     new Duration(spareTime, DurationUnit.SI));
                             // This line was missing...
                             value = value.plus(new Length(remainingDistance, LengthUnit.SI));
                             // Use the minimum of the value computed for the first split junction (if there is one)
                             // and the value computed for the second split junction.
                             suitabilityOfLanesBeforeBranch.put(l,
                                     null == currentValue || value.le(currentValue) ? value : currentValue);
                         }
                     }
                 }
             }
         }
         if (suitabilityOfLanesBeforeBranch.size() == 0)
         {
             throw new NetworkException("No lanes available on Link " + linkBeforeBranch);
         }
         Length currentLaneSuitability = suitabilityOfLanesBeforeBranch.get(currentLane);
         if (null != currentLaneSuitability)
         {
             return currentLaneSuitability; // Following the current lane will keep us on the Route
         }
         // Performing one or more lane changes (left or right) is required.
         int totalLanes = countCompatibleLanes(currentLane.getParentLink(), gtu.getGTUType(), GTUDirectionality.DIR_PLUS);
         Length leftSuitability =
                 computeSuitabilityWithLaneChanges(currentLane, remainingDistance, suitabilityOfLanesBeforeBranch, totalLanes,
                         LateralDirectionality.LEFT, gtu.getGTUType(), GTUDirectionality.DIR_PLUS);
         Length rightSuitability =
                 computeSuitabilityWithLaneChanges(currentLane, remainingDistance, suitabilityOfLanesBeforeBranch, totalLanes,
                         LateralDirectionality.RIGHT, gtu.getGTUType(), GTUDirectionality.DIR_PLUS);
         if (leftSuitability.ge(rightSuitability))
         {
             return leftSuitability;
         }
         else if (rightSuitability.ge(leftSuitability))
         {
             // TODO
             return rightSuitability;
         }
         if (leftSuitability.le(GETOFFTHISLANENOW))
         {
             throw new NetworkException("Changing lanes in any direction does not get the GTU on a suitable lane");
         }
         return leftSuitability; // left equals right; this is odd but topologically possible
     }
 
     /**
      * Compute the suitability of a lane from which lane changes are required to get to the next point on the Route.<br>
      * This method weighs the suitability of the nearest suitable lane by (m - n) / m where n is the number of lane changes
      * required and m is the total number of lanes in the CrossSectionLink.
      * @param startLane Lane; the current lane of the GTU
      * @param remainingDistance double; distance in m of GTU to first branch
      * @param suitabilities Map&lt;Lane, Double&gt;; the set of suitable lanes and their suitability
      * @param totalLanes integer; total number of lanes compatible with the GTU type
      * @param direction LateralDirectionality; the direction of the lane changes to attempt
      * @param gtuType GTUType; the type of the GTU
      * @param drivingDirection GTUDirectionality; the driving direction of the GTU
      * @return double; the suitability of the <cite>startLane</cite> for following the Route
      */
     protected final Length computeSuitabilityWithLaneChanges(final Lane startLane, final double remainingDistance,
             final Map<Lane, Length> suitabilities, final int totalLanes, final LateralDirectionality direction,
             final GTUType gtuType, final GTUDirectionality drivingDirection)
     {
         /*-
          * The time per required lane change seems more relevant than distance per required lane change.
          * Total time required does not grow linearly with the number of required lane changes. Logarithmic, arc tangent 
          * is more like it.
          * Rijkswaterstaat appears to use a fixed time for ANY number of lane changes (about 60s). 
          * TomTom navigation systems give more time (about 90s).
          * In this method the returned suitability decreases linearly with the number of required lane changes. This
          * ensures that there is a gradient that coaches the GTU towards the most suitable lane.
          */
         int laneChangesUsed = 0;
         Lane currentLane = startLane;
         Length currentSuitability = null;
         while (null == currentSuitability)
         {
             laneChangesUsed++;
             if (currentLane.accessibleAdjacentLanesLegal(direction, gtuType, drivingDirection).size() == 0)
             {
                 return GETOFFTHISLANENOW;
             }
             currentLane = currentLane.accessibleAdjacentLanesLegal(direction, gtuType, drivingDirection).iterator().next();
             currentSuitability = suitabilities.get(currentLane);
         }
         double fraction = currentSuitability == NOLANECHANGENEEDED ? 0 : 0.5;
         int notSuitableLaneCount = totalLanes - suitabilities.size();
         return new Length(
                 remainingDistance * (notSuitableLaneCount - laneChangesUsed + 1 + fraction) / (notSuitableLaneCount + fraction),
                 LengthUnit.SI);
     }
 
     /**
      * Determine how many lanes on a CrossSectionLink are compatible with a particular GTU type.<br>
      * TODO: this method should probably be moved into the CrossSectionLink class
      * @param link CrossSectionLink; the link
      * @param gtuType GTUType; the GTU type
      * @param drivingDirection GTUDirectionality; the driving direction on the link
      * @return integer; the number of lanes on the link that are compatible with the GTU type
      */
     protected final int countCompatibleLanes(final CrossSectionLink link, final GTUType gtuType,
             final GTUDirectionality drivingDirection)
     {
         int result = 0;
         for (CrossSectionElement cse : link.getCrossSectionElementList())
         {
             if (cse instanceof Lane)
             {
                 Lane l = (Lane) cse;
                 if (l.getLaneType().isCompatible(gtuType, drivingDirection))
                 {
                     result++;
                 }
             }
         }
         return result;
     }
 
     /** {@inheritDoc} */
     @Override
     public final String toString()
     {
         return "LaneBasedCFLCTacticalPlanner [laneChangeModel=" + this.laneChangeModel + "]";
     }
 
 }