package org.opentrafficsim.road.gtu.lane.tactical.following;
   
   import java.io.Serializable;
   import java.util.ArrayList;
   import java.util.List;
   import java.util.Set;
   
   import org.djunits.unit.TimeUnit;
   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.opentrafficsim.base.parameters.ParameterException;
  import org.opentrafficsim.base.parameters.Parameters;
  import org.opentrafficsim.road.gtu.lane.perception.PerceptionIterable;
  import org.opentrafficsim.road.gtu.lane.perception.headway.Headway;
  import org.opentrafficsim.road.network.speed.SpeedLimitInfo;
  
  import nl.tudelft.simulation.dsol.simulators.DEVSSimulatorInterface;
  
  /**
   * Extended version of FixedAccelerationModel. The addition is that this GTUFollowingModel stores a series of acceleration and
   * duration values. Mostly used for testing.
   * <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/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 6 feb. 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 SequentialFixedAccelerationModel extends AbstractGTUFollowingModelMobil implements Serializable
  {
      /** */
      private static final long serialVersionUID = 20150206L;
  
      /** The list of result values of this SequentialFixedAccelerationModel. */
      private final List<FixedAccelerationModel> steps = new ArrayList<>();
  
      /** The simulator engine. */
      private final DEVSSimulatorInterface.TimeDoubleUnit simulator;
  
      /** The maximum safe deceleration. */
      private final Acceleration maximumSafeDeceleration;
  
      /**
       * Construct a SequentialFixedAccelerationModel with empty list of FixedAccelerationModel steps.
       * @param simulator DEVSSimulatorInterface.TimeDoubleUnit; the simulator (needed to obtain the current simulation time)
       * @param maximumSafeDeceleration Acceleration; specified maximum safe deceleration
       */
      public SequentialFixedAccelerationModel(final DEVSSimulatorInterface.TimeDoubleUnit simulator,
              final Acceleration maximumSafeDeceleration)
      {
          this.simulator = simulator;
          this.maximumSafeDeceleration = maximumSafeDeceleration;
      }
  
      /**
       * Construct a SequentialFixedAccelerationModel and load it with a list of FixedAccelerationModel steps.
       * @param simulator DEVSSimulatorInterface.TimeDoubleUnit; the simulator (needed to obtain the current simulation time)
       * @param maximumSafeDeceleration Acceleration; specified maximum safe deceleration
       * @param steps Set&lt;FixedAccelerationModel&gt;; the list of FixedAccelerationModel steps.
       */
      public SequentialFixedAccelerationModel(final DEVSSimulatorInterface.TimeDoubleUnit simulator,
              final Acceleration maximumSafeDeceleration, final Set<FixedAccelerationModel> steps)
      {
          this(simulator, maximumSafeDeceleration);
          this.steps.addAll(steps);
      }
  
      /**
       * Add one FixedAccelerationModel step to this SequentialFixedAccelerationModel.
       * @param step FixedAccelerationModel; the step to add
       * @return SequentialFixedAccelerationModel; this modified SequentialFixedAccelerationModel
       */
      public final SequentialFixedAccelerationModel addStep(final FixedAccelerationModel step)
      {
          this.steps.add(step);
          return this;
      }
  
      /**
       * Retrieve the number of FixedAccelerationModel steps in this SequentialFixedAccelerationModel.
       * @return int; the number of steps in this SequentialFixedAccelerationModel
       */
      public final int size()
      {
          return this.steps.size();
      }
  
      /**
       * Retrieve one FixedAccelerationModel step.
       * @param index int; the index of the retrieved FixedAccelerationModel step
       * @return FixedAccelerationModel
       */
      public final FixedAccelerationModel get(final int index)
      {
         return this.steps.get(index);
     }
 
     /**
      * Retrieve the simulation time at the end of the Nth step of this SequentialFixedAccelerationModel.
      * @param index int; the step
      * @return Time
      */
     public final Time timeAfterCompletionOfStep(final int index)
     {
         Time sum = new Time(0, TimeUnit.BASE);
         for (int i = 0; i <= index; i++)
         {
             sum = sum.plus(this.steps.get(i).getDuration());
         }
         return sum;
     }
 
     /** Maximum error of the simulator clock. */
     private static final double MAXIMUMTIMEERROR = 0.001; // 1 millisecond
 
     /**
      * Find the FixedAccelerationModel that starts at the current simulator time.
      * @return FixedAccelerationModel; the FixedAccelerationModel that starts at the current simulator time
      */
     private FixedAccelerationModel getAccelerationModel()
     {
         Time when = this.simulator.getSimulatorTime();
         double remainingTime = when.getSI();
         for (FixedAccelerationModel step : this.steps)
         {
             if (remainingTime < -MAXIMUMTIMEERROR)
             {
                 throw new Error("FixedSequentialAcceleration does not have a result for " + when);
             }
             if (remainingTime < MAXIMUMTIMEERROR)
             {
                 return step;
             }
             remainingTime -= step.getDuration().getSI();
         }
         throw new Error("FixedSequentialAcceleration does not have a result for " + when);
     }
 
     /** {@inheritDoc} */
     @Override
     public final Acceleration computeAcceleration(final Speed followerSpeed, final Speed followerMaximumSpeed,
             final Speed leaderSpeed, final Length headway, final Speed speedLimit)
     {
         return getAccelerationModel().getAcceleration();
     }
 
     /** {@inheritDoc} */
     @Override
     public final Acceleration computeAcceleration(final Speed followerSpeed, final Speed followerMaximumSpeed,
             final Speed leaderSpeed, final Length headway, final Speed speedLimit, final Duration stepSize)
     {
         // TODO incorporate stepSize
         return getAccelerationModel().getAcceleration();
     }
 
     /** {@inheritDoc} */
     @Override
     public final Acceleration getMaximumSafeDeceleration()
     {
         return this.maximumSafeDeceleration;
     }
 
     /** {@inheritDoc} */
     @Override
     public final Duration getStepSize()
     {
         return getAccelerationModel().getStepSize();
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getName()
     {
         return "FSAM";
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getLongName()
     {
         return "Fixed sequential acceleration model";
     }
 
     /** {@inheritDoc} */
     @Override
     public final void setA(final Acceleration a)
     {
         //
     }
 
     /** {@inheritDoc} */
     @Override
     public final void setT(final Duration t)
     {
         //
     }
 
     /** {@inheritDoc} */
     @Override
     public final void setFspeed(final double fSpeed)
     {
         //
     }
 
     // The following is inherited from CarFollowingModel
 
     /** {@inheritDoc} */
     @Override
     public final Speed desiredSpeed(final Parameters parameters, final SpeedLimitInfo speedInfo) throws ParameterException
     {
         return null;
     }
 
     /** {@inheritDoc} */
     @Override
     public final Length desiredHeadway(final Parameters parameters, final Speed speed) throws ParameterException
     {
         return null;
     }
 
     /** {@inheritDoc} */
     @Override
     public final Acceleration followingAcceleration(final Parameters parameters, final Speed speed,
             final SpeedLimitInfo speedInfo, final PerceptionIterable<? extends Headway> leaders) throws ParameterException
     {
         return null;
     }
 
     /** {@inheritDoc} */
     @Override
     public final String toString()
     {
         return "SequentialFixedAccelerationModel [steps=" + this.steps + ", maximumSafeDeceleration="
                 + this.maximumSafeDeceleration + "]";
     }
 
 }