package org.opentrafficsim.road.gtu.lane.perception.categories;
   
   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;
   
   /**
    * Form of anticipation.
   * <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/node/13">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version 24 feb. 2017 <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 interface Anticipation
  {
  
      /** Assume no anticipation. */
      public final static Anticipation NONE = new Anticipation()
      {
          @Override
          public NeighborTriplet anticipate(final NeighborTriplet neighborTriplet, final Duration duration,
                  final Length traveledDistance)
          {
              return neighborTriplet;
          }
  
          @Override
          public Length egoAnticipation(final Speed speed, final Acceleration acceleration, final Duration duration)
          {
              return Length.ZERO;
          }
      };
  
      /** Assume constant speed. */
      public final static Anticipation CONSTANT_SPEED = new Anticipation()
      {
          @Override
          public NeighborTriplet anticipate(final NeighborTriplet neighborTriplet, final Duration duration,
                  final Length traveledDistance)
          {
              return new NeighborTriplet(
                      neighborTriplet.getHeadway().plus(neighborTriplet.getSpeed().multiplyBy(duration)).minus(traveledDistance),
                      neighborTriplet.getSpeed(), neighborTriplet.getAcceleration());
          }
  
          @Override
          public Length egoAnticipation(final Speed speed, final Acceleration acceleration, final Duration duration)
          {
              return speed.multiplyBy(duration);
          }
      };
  
      /** Assume constant acceleration. */
      public final static Anticipation CONSTANT_ACCELERATION = new Anticipation()
      {
          @Override
          public NeighborTriplet anticipate(final NeighborTriplet neighborTriplet, final Duration duration,
                  final Length traveledDistance)
          {
              if (neighborTriplet.getSpeed().si < -neighborTriplet.getAcceleration().si * duration.si)
              {
                  // to stand still
                  double t = neighborTriplet.getSpeed().si / -neighborTriplet.getAcceleration().si;
                  double dx = neighborTriplet.getSpeed().si * t + .5 * neighborTriplet.getAcceleration().si * t * t;
                  return new NeighborTriplet(Length.createSI(neighborTriplet.getHeadway().si + dx - traveledDistance.si),
                          Speed.ZERO, Acceleration.ZERO);
              }
              double dx = neighborTriplet.getSpeed().si * duration.si
                      + .5 * neighborTriplet.getAcceleration().si * duration.si * duration.si;
              double dv = neighborTriplet.getAcceleration().si * duration.si;
              return new NeighborTriplet(Length.createSI(neighborTriplet.getHeadway().si + dx - traveledDistance.si),
                      Speed.createSI(neighborTriplet.getSpeed().si + dv), neighborTriplet.getAcceleration());
          }
  
          @Override
          public Length egoAnticipation(final Speed speed, final Acceleration acceleration, final Duration duration)
          {
              return speed.multiplyBy(duration);
          }
      };
  
      /**
       * Anticipate movement.
       * @param neighborTriplet headway, speed and acceleration
       * @param duration duration
       * @param traveledDistance distance the subject vehicle traveled during the anticipation time
       * @return anticipated info
       */
      NeighborTriplet anticipate(NeighborTriplet neighborTriplet, Duration duration, Length traveledDistance);
  
      /**
       * Anticipate own movement.
       * @param speed current speed
       * @param acceleration current acceleration
      * @param duration anticipation time
      * @return anticipated distance traveled
      */
     Length egoAnticipation(Speed speed, Acceleration acceleration, Duration duration);
 
     /**
      * Results from anticipation.
      * <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/node/13">OpenTrafficSim License</a>.
      * <p>
      * @version $Revision$, $LastChangedDate$, by $Author$, initial version 24 feb. 2017 <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 static class NeighborTriplet
     {
 
         /** Headway. */
         private final Length headway;
 
         /** Speed. */
         private final Speed speed;
 
         /** Acceleration. */
         private final Acceleration acceleration;
 
         /**
          * @param headway headway
          * @param speed speed
          * @param acceleration acceleration
          */
         NeighborTriplet(final Length headway, final Speed speed, final Acceleration acceleration)
         {
             this.headway = headway;
             this.speed = speed;
             this.acceleration = acceleration;
         }
 
         /**
          * @return headway.
          */
         public Length getHeadway()
         {
             return this.headway;
         }
 
         /**
          * @return speed.
          */
         public Speed getSpeed()
         {
             return this.speed;
         }
 
         /**
          * @return acceleration.
          */
         public Acceleration getAcceleration()
         {
             return this.acceleration;
         }
 
         /** {@inheritDoc} */
         @Override
         public final String toString()
         {
             return "NeighborTriplet [headway=" + this.headway + ", speed=" + this.speed + ", acceleration=" + this.acceleration
                     + "]";
         }
     }
 }