package org.opentrafficsim.road.gtu.generator;
   
   import java.util.LinkedList;
   import java.util.Queue;
   import java.util.Set;
   
   import javax.naming.NamingException;
   
   import nl.tudelft.simulation.dsol.SimRuntimeException;
  
  import org.djunits.unit.LengthUnit;
  import org.djunits.unit.TimeUnit;
  import org.djunits.value.vdouble.scalar.Length;
  import org.djunits.value.vdouble.scalar.Speed;
  import org.djunits.value.vdouble.scalar.Time;
  import org.opentrafficsim.core.distributions.Generator;
  import org.opentrafficsim.core.distributions.ProbabilityException;
  import org.opentrafficsim.core.dsol.OTSDEVSSimulatorInterface;
  import org.opentrafficsim.core.geometry.OTSGeometryException;
  import org.opentrafficsim.core.gtu.GTUException;
  import org.opentrafficsim.core.gtu.RelativePosition;
  import org.opentrafficsim.core.gtu.animation.GTUColorer;
  import org.opentrafficsim.core.network.NetworkException;
  import org.opentrafficsim.core.network.OTSNetwork;
  import org.opentrafficsim.road.gtu.animation.DefaultCarAnimation;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTU;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTUCharacteristics;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTUCharacteristicsGenerator;
  import org.opentrafficsim.road.gtu.lane.LaneBasedIndividualGTU;
  import org.opentrafficsim.road.network.lane.DirectedLanePosition;
  import org.opentrafficsim.road.network.lane.Lane;
  
  /**
   * Lane based GTU generator. This generator generates lane based GTUs using a LaneBasedTemplateGTUType. The template is used to
   * generate a set of GTU characteristics at the times implied by the headway generator. These sets are queued until there is
   * sufficient room to construct a GTU at the specified lane locations. The speed of a construction GTU may be reduced to ensure
   * it does not run into its immediate leader GTU.
   * <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/node/13">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version Mar 8, 2016 <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 LaneBasedGTUGenerator
  {
      /** FIFO for templates that have not been generated yet due to insufficient room/headway. */
      private final Queue<LaneBasedGTUCharacteristics> unplacedTemplates = new LinkedList<LaneBasedGTUCharacteristics>();
  
      /** Name of the GTU generator. */
      private final String id;
  
      /** Time distribution that determines the interval times between GTUs. */
      private final Generator<Time.Rel> interarrivelTimeGenerator;
  
      /** Generates most properties of the GTUs. */
      private final LaneBasedGTUCharacteristicsGenerator laneBasedGTUCharacteristicsGenerator;
  
      /** End time of this generator. */
      private final Time.Abs endTime;
  
      /** Maximum number of GTUs to generate. */
      private final long maxGTUs;
  
      /** Total number of GTUs generated so far. */
      private long generatedGTUs = 0;
  
      /** Retry interval for checking if a GTU can be placed. */
      Time.Rel reTryInterval = new Time.Rel(0.1, TimeUnit.SI);
  
      /** The location and initial direction of the generated GTUs. */
      final Set<DirectedLanePosition> initialLongitudinalPositions;
  
      /** The way that this generator checks if it is safe to construct and place the next lane based GTU. */
      final RoomChecker roomChecker;
  
      /** The GTU colorer that will be linked to each generated GTU. */
      final GTUColorer gtuColorer;
  
      /**
       * Construct a new lane base GTU generator.
       * @param id String; name of the new GTU generator
       * @param interarrivelTimeGenerator Generator&lt;Time.Rel&gt;; generator for the interval times between GTUs
       * @param maxGTUs long; maximum number of GTUs to generate
       * @param startTime Time.Abs; time at which the first GTU will be generated
       * @param endTime Time.Abs; time after which no more GTUs will be generated
       * @param gtuColorer GTUColorer; the GTU colorer that will be used by all generated GTUs
       * @param laneBasedGTUCharacteristicsGenerator LaneBasedGTUCharacteristicsGenerator; generator of the characteristics of
       *            each GTU
       * @param initialLongitudinalPositions SET&lt;DirectedLanePosition&gt;; the location and initial direction of all generated
       *            GTUs
       * @param network OTSNetwork; the OTS network that owns the generated GTUs
       * @param roomChecker LaneBasedGTUGenerator.RoomChecker; the way that this generator checks that there is sufficient room to
       *            place a new GTU
       * @throws SimRuntimeException when <cite>startTime</cite> lies before the current simulation time
       * @throws ProbabilityException pe
       */
      public LaneBasedGTUGenerator(String id, final Generator<Time.Rel> interarrivelTimeGenerator, final long maxGTUs,
             final Time.Abs startTime, final Time.Abs endTime, final GTUColorer gtuColorer,
             final LaneBasedGTUCharacteristicsGenerator laneBasedGTUCharacteristicsGenerator,
             final Set<DirectedLanePosition> initialLongitudinalPositions, final OTSNetwork network, RoomChecker roomChecker)
             throws SimRuntimeException, ProbabilityException
     {
         this.id = id;
         this.interarrivelTimeGenerator = interarrivelTimeGenerator;
         this.laneBasedGTUCharacteristicsGenerator = laneBasedGTUCharacteristicsGenerator;
         this.endTime = endTime;
         this.maxGTUs = maxGTUs;
         this.initialLongitudinalPositions = initialLongitudinalPositions;
         this.roomChecker = roomChecker;
         this.gtuColorer = gtuColorer;
         laneBasedGTUCharacteristicsGenerator.getSimulator().scheduleEventAbs(startTime, this, this, "generateCharacteristics",
                 new Object[] {});
     }
 
     /**
      * Generate the characteristics of the next GTU.
      * @throws ProbabilityException when something is wrongly defined in the LaneBasedTemplateGTUType
      * @throws SimRuntimeException when this method fails to re-schedule itself or the call to the method that tries to place a
      *             GTU on the road
      */
     @SuppressWarnings("unused")
     private void generateCharacteristics() throws ProbabilityException, SimRuntimeException
     {
         OTSDEVSSimulatorInterface simulator = this.laneBasedGTUCharacteristicsGenerator.getSimulator();
         if (this.generatedGTUs >= this.maxGTUs
                 || this.laneBasedGTUCharacteristicsGenerator.getSimulator().getSimulatorTime().get().ge(this.endTime))
         {
             return; // Do not reschedule
         }
         synchronized (this.unplacedTemplates)
         {
             this.generatedGTUs++;
             this.unplacedTemplates.add(this.laneBasedGTUCharacteristicsGenerator.draw());
             if (this.unplacedTemplates.size() == 1)
             {
                 simulator.scheduleEventNow(this, this, "tryToPlaceGTU", new Object[] {});
             }
         }
         if (this.generatedGTUs < this.maxGTUs)
         {
             simulator.scheduleEventRel(this.interarrivelTimeGenerator.draw(), this, this, "generateCharacteristics",
                     new Object[] {});
         }
     }
 
     /** Last reported queue length. */
     private int lastReportedQueueLength = 0;
 
     /**
      * Check if the queue is non-empty and, if it is, try to place the GTUs in the queue on the road.
      * @throws SimRuntimeException should never happen
      * @throws GTUException when something wrong in the definition of the GTU
      * @throws OTSGeometryException when something is wrong in the definition of the GTU
      * @throws NetworkException when something is wrong with the initial location of the GTU
      * @throws NamingException ???
      * @throws ProbabilityException pe
      */
     @SuppressWarnings("unused")
     private void tryToPlaceGTU() throws SimRuntimeException, GTUException, NamingException, NetworkException,
             OTSGeometryException, ProbabilityException
     {
         // System.out.println("entered tryToPlaceGTU");
         LaneBasedGTUCharacteristics characteristics;
         OTSDEVSSimulatorInterface simulator = this.laneBasedGTUCharacteristicsGenerator.getSimulator();
         synchronized (this.unplacedTemplates)
         {
             characteristics = this.unplacedTemplates.peek();
         }
         if (null == characteristics)
         {
             return; // Do not re-schedule this method
         }
         Length.Rel shortestHeadway = new Length.Rel(Double.MAX_VALUE, LengthUnit.SI);
         Speed leaderSpeed = null;
         for (DirectedLanePosition dlp : this.initialLongitudinalPositions)
         {
             Lane lane = dlp.getLane();
             // GOTCHA look for the first GTU with FRONT after the start position (not REAR)
             LaneBasedGTU leader =
                     lane.getGtuAhead(dlp.getPosition(), dlp.getGtuDirection(), RelativePosition.FRONT, simulator
                             .getSimulatorTime().getTime());
             if (null != leader)
             {
                 Length.Rel headway = leader.position(lane, leader.getRear()).minus(dlp.getPosition());
                 if (headway.si < 0)
                 {
                     headway = new Length.Rel(Math.abs(headway.si), headway.getUnit());
                 }
                 headway = new Length.Rel(headway.si - characteristics.getLength().si / 2, LengthUnit.SI);
                 if (shortestHeadway.gt(headway))
                 {
                     shortestHeadway = headway;
                     leaderSpeed = leader.getVelocity();
                 }
             }
         }
         if (shortestHeadway.si > 0)
         {
             Speed safeSpeed = characteristics.getVelocity();
             if (null != leaderSpeed)
             {
                 safeSpeed = this.roomChecker.canPlace(leaderSpeed, shortestHeadway, characteristics);
             }
             if (null != safeSpeed)
             {
                 // There is enough room; remove the template from the queue and construct the new GTU
                 synchronized (this.unplacedTemplates)
                 {
                     this.unplacedTemplates.remove();
                 }
                 if (safeSpeed.gt(characteristics.getMaximumVelocity()))
                 {
                     safeSpeed = characteristics.getMaximumVelocity();
                 }
                 String gtuId = null == characteristics.getIdGenerator() ? null : characteristics.getIdGenerator().nextId();
                 new LaneBasedIndividualGTU(gtuId, characteristics.getGTUType(), this.initialLongitudinalPositions, safeSpeed,
                         characteristics.getLength(), characteristics.getWidth(), characteristics.getMaximumVelocity(),
                         simulator, characteristics.getStrategicalPlanner(), characteristics.getPerception(),
                         DefaultCarAnimation.class, this.gtuColorer, characteristics.getNetwork());
                 // System.out.println("tryToPlace: Constructed GTU on " + this.initialLongitudinalPositions);
             }
         }
         int queueLength = this.unplacedTemplates.size();
         if (queueLength != this.lastReportedQueueLength)
         {
             System.out.println("Generator " + this.id + ": queue length is " + queueLength + " at time "
                     + simulator.getSimulatorTime().get());
             this.lastReportedQueueLength = queueLength;
         }
         if (queueLength > 0)
         {
             // System.out.println("Re-scheduling tryToPlace, queue length is " + this.unplacedTemplates.size());
             this.laneBasedGTUCharacteristicsGenerator.getSimulator().scheduleEventRel(this.reTryInterval, this, this,
                     "tryToPlaceGTU", new Object[] {});
         }
     }
 
     /** {@inheritDoc} */
     public String toString()
     {
         return "LaneBasedGTUGenerator " + this.id + " on " + this.initialLongitudinalPositions;
     }
 
     /**
      * @return generatedGTUs.
      */
     public long getGeneratedGTUs()
     {
         return this.generatedGTUs;
     }
 
     /**
      * @param generatedGTUs set generatedGTUs.
      */
     public void setGeneratedGTUs(long generatedGTUs)
     {
         this.generatedGTUs = generatedGTUs;
     }
 
     /**
      * Retrieve the id of this LaneBasedGTUGenerator.
      * @return String; the id of this LaneBasedGTUGenerator
      */
     public String getId()
     {
         return this.id;
     }
 
     /**
      * Retrieve the end time of this LaneBasedGTUGenerator.
      * @return Time.Abs; the time after which this LaneBasedGTUGenerator will not generate any more GTUs
      */
     public Time.Abs getEndTime()
     {
         return this.endTime;
     }
 
     /**
      * Retrieve the maximum number of GTUs to generate.
      * @return long; once this number of GTUS is generated, this LaneBasedGTUGenerator will stop generating any more GTUs
      */
     public long getMaxGTUs()
     {
         return this.maxGTUs;
     }
 
     /**
      * Retrieve the GTUColorer that this LaneBasedGTUGenerator assigns to all generated GTUs.
      * @return GtuColorer; the GTUColorer that this LaneBasedGTUGenerator assigns to all generated GTUs
      */
     public GTUColorer getGtuColorer()
     {
         return this.gtuColorer;
     }
 
     /**
      * Interface for class that checks that there is sufficient room for a proposed new GTU and returns the maximum safe speed
      * for the proposed new GTU.
      */
     public interface RoomChecker
     {
         /**
          * Return the maximum safe speed for a new GTU with the specified characteristics. Return null if there is no safe
          * speed. This method will never be called if the newly proposed GTU overlaps with the leader. Nor will this method be
          * called if there is no leader.
          * @param leaderSpeed Speed; velocity of the nearest leader
          * @param headway Length.Rel; net distance to the nearest leader (always &gt; 0)
          * @param laneBasedGTUCharacteristics LaneBasedGTUCharacteristics; characteristics of the proposed new GTU
          * @return Speed; maximum safe speed, or null if a GTU with the specified characteristics cannot be placed at the
          *         current time
          * @throws NetworkException this method may throw a NetworkException if it encounters an error in the network structure
          */
         public Speed canPlace(final Speed leaderSpeed, final Length.Rel headway,
                 final LaneBasedGTUCharacteristics laneBasedGTUCharacteristics) throws NetworkException;
     }
 
 }