package org.opentrafficsim.road.gtu.following;
   
   import java.util.ArrayList;
   import java.util.List;
   import java.util.Set;
   
   import org.opentrafficsim.core.dsol.OTSDEVSSimulatorInterface;
   
   /**
   * 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) 2013-2015 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 AbstractGTUFollowingModel
  {
      /** The list of result values of this SequentialFixedAccelerationModel. */
      private final List<FixedAccelerationModel> steps = new ArrayList<FixedAccelerationModel>();
  
      /** The simulator engine. */
      private final OTSDEVSSimulatorInterface simulator;
  
      /**
       * Construct a SequentialFixedAccelerationModel with empty list of FixedAccelerationModel steps.
       * @param simulator DEVSSimulator; the simulator (needed to obtain the current simulation time)
       */
      public SequentialFixedAccelerationModel(final OTSDEVSSimulatorInterface simulator)
      {
          this.simulator = simulator;
      }
  
      /**
       * Construct a SequentialFixedAccelerationModel and load it with a list of FixedAccelerationModel steps.
       * @param simulator DEVSSimulator; the simulator (needed to obtain the current simulation time)
       * @param steps Set&lt;FixedAccelerationModel&gt;; the list of FixedAccelerationModel steps.
       */
      public SequentialFixedAccelerationModel(final OTSDEVSSimulatorInterface simulator,
          final Set<FixedAccelerationModel> steps)
      {
          this(simulator);
          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 DoubleScalar.Abs&lt;TimeUnit&gt;
       */
      public final Time.Abs timeAfterCompletionOfStep(final int index)
      {
          Time.Abs sum = new Time.Abs(0, SECOND);
          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.Abs when = this.simulator.getSimulatorTime().getTime();
         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.Abs computeAcceleration(final Speed.Abs followerSpeed,
         final Speed.Abs followerMaximumSpeed, final Speed.Abs leaderSpeed, final Length.Rel headway,
         final Speed.Abs speedLimit)
     {
         return getAccelerationModel().getAcceleration();
     }
 
     /** {@inheritDoc} */
     @Override
     public final Acceleration.Abs maximumSafeDeceleration()
     {
         return new Acceleration.Abs(2, METER_PER_SECOND_2);
     }
 
     /** {@inheritDoc} */
     @Override
     public final Time.Rel getStepSize()
     {
         return getAccelerationModel().getStepSize();
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getName()
     {
         return "FSAM";
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getLongName()
     {
         return "Fixed sequential acceleration model";
     }
 
 }