package org.opentrafficsim.road.gtu.perception.mental.channel;
   
   import java.util.Iterator;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.djutils.exceptions.Throw;
   import org.djutils.exceptions.Try;
   import org.opentrafficsim.base.OtsRuntimeException;
   import org.opentrafficsim.base.parameters.ParameterException;
  import org.opentrafficsim.base.parameters.ParameterTypeLength;
  import org.opentrafficsim.base.parameters.ParameterTypes;
  import org.opentrafficsim.core.gtu.RelativePosition;
  import org.opentrafficsim.core.gtu.perception.AbstractPerceptionCategory;
  import org.opentrafficsim.core.network.LateralDirectionality;
  import org.opentrafficsim.core.network.route.Route;
  import org.opentrafficsim.road.gtu.LaneBasedGtu;
  import org.opentrafficsim.road.gtu.perception.LanePerception;
  import org.opentrafficsim.road.gtu.perception.PerceptionCollectable;
  import org.opentrafficsim.road.gtu.perception.PerceptionReiterable;
  import org.opentrafficsim.road.gtu.perception.RelativeLane;
  import org.opentrafficsim.road.gtu.perception.categories.DirectIntersectionPerception;
  import org.opentrafficsim.road.gtu.perception.categories.IntersectionPerception;
  import org.opentrafficsim.road.gtu.perception.categories.neighbors.Anticipation;
  import org.opentrafficsim.road.gtu.perception.categories.neighbors.Estimation;
  import org.opentrafficsim.road.gtu.perception.categories.neighbors.PerceivedGtuType;
  import org.opentrafficsim.road.gtu.perception.categories.neighbors.PerceivedGtuType.AnticipationPerceivedGtuType;
  import org.opentrafficsim.road.gtu.perception.object.PerceivedConflict;
  import org.opentrafficsim.road.gtu.perception.object.PerceivedTrafficLight;
  import org.opentrafficsim.road.gtu.perception.object.PerceivedTrafficLightChannel;
  import org.opentrafficsim.road.gtu.perception.structure.NavigatingIterable.Entry;
  import org.opentrafficsim.road.network.conflict.Conflict;
  import org.opentrafficsim.road.network.object.trafficlight.TrafficLight;
  
  /**
   * This class is highly similar to {@link DirectIntersectionPerception} but takes perception delay for conflicting GTUs and
   * traffic light colors from perception channels.
   * <p>
   * Copyright (c) 2024-2026 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * </p>
   * @author Wouter Schakel
   */
  public class IntersectionPerceptionChannel extends AbstractPerceptionCategory<LaneBasedGtu, LanePerception>
          implements IntersectionPerception
  {
  
      /** Mental module. */
      private final ChannelMental mental;
  
      /** Estimation. */
      private final Estimation estimation;
  
      /** Anticipation. */
      private final Anticipation anticipation;
  
      /** Look ahead parameter type. */
      protected static final ParameterTypeLength LOOKAHEAD = ParameterTypes.LOOKAHEAD;
  
      /**
       * Constructor.
       * @param perception perception.
       * @param estimation estimation.
       * @param anticipation anticipation.
       */
      public IntersectionPerceptionChannel(final LanePerception perception, final Estimation estimation,
              final Anticipation anticipation)
      {
          super(perception);
          Throw.when(!(getPerception().getMental().get() instanceof ChannelMental), IllegalArgumentException.class,
                  "Mental module is not channel based.");
          this.mental = (ChannelMental) getPerception().getMental().get();
          this.estimation = estimation;
          this.anticipation = anticipation;
      }
  
      @Override
      public final PerceptionCollectable<PerceivedTrafficLight, TrafficLight> getTrafficLights(final RelativeLane lane)
      {
          return computeIfAbsent("trafficLights", () -> computeTrafficLights(lane), lane);
      }
  
      @Override
      public final PerceptionCollectable<PerceivedConflict, Conflict> getConflicts(final RelativeLane lane)
      {
          return computeIfAbsent("conflicts", () -> computeConflicts(lane), lane);
      }
  
      @Override
      public final boolean isAlongsideConflictLeft()
      {
          return computeIfAbsent("alongside", () -> computeConflictAlongside(LateralDirectionality.LEFT),
                  LateralDirectionality.LEFT);
      }
  
      @Override
      public final boolean isAlongsideConflictRight()
      {
          return computeIfAbsent("alongside", () -> computeConflictAlongside(LateralDirectionality.RIGHT),
                  LateralDirectionality.RIGHT);
     }
 
     /**
      * Compute traffic lights.
      * @param lane lane
      * @return PerceptionCollectable of traffic lights
      */
     private PerceptionCollectable<PerceivedTrafficLight, TrafficLight> computeTrafficLights(final RelativeLane lane)
     {
         Iterable<Entry<TrafficLight>> iterable = Try.assign(() ->
         {
             return getPerception().getLaneStructure().getDownstreamObjects(lane, TrafficLight.class, RelativePosition.FRONT,
                     true);
         }, "Unable to get downstream traffic lights from LaneStructure");
         Route route = getPerception().getGtu().getStrategicalPlanner().getRoute()
                 .orElseThrow(() -> new OtsRuntimeException("Unable to obtain route"));
         return new PerceptionReiterable<>(getGtu(), iterable, (trafficLight, distance) ->
         {
             return new PerceivedTrafficLightChannel(trafficLight, distance,
                     trafficLight.canTurnOnRed(route, getGtu().getType()),
                     () -> IntersectionPerceptionChannel.this.mental.getPerceptionDelay(ChannelTask.FRONT));
         });
     }
 
     /**
      * Compute conflicts.
      * @param lane lane
      * @return PerceptionCollectable of conflicts
      */
     private PerceptionCollectable<PerceivedConflict, Conflict> computeConflicts(final RelativeLane lane)
     {
         Iterable<Entry<Conflict>> iterable = Try.assign(() -> getPerception().getLaneStructure().getDownstreamObjects(lane,
                 Conflict.class, RelativePosition.FRONT, true), "Unable to get downstream conflicts from LaneStructure");
         return new PerceptionReiterable<>(getGtu(), iterable, (conflict, distance) ->
         {
             Length lookAhead = getGtu().getParameters().getOptionalParameter(LOOKAHEAD)
                     .orElseThrow(() -> new OtsRuntimeException("Parameter LOOKAHEAD not present."));
             // TODO visibility
             Length conflictingVisibility = lookAhead;
             PerceivedConflict perceivedConflict;
             PerceivedGtuType perceivedGtuType = new AnticipationPerceivedGtuType(IntersectionPerceptionChannel.this.estimation,
                     IntersectionPerceptionChannel.this.anticipation,
                     () -> IntersectionPerceptionChannel.this.mental.getPerceptionDelay(conflict));
             perceivedConflict = PerceivedConflict.of(getGtu(), conflict, perceivedGtuType, distance, conflictingVisibility);
             return perceivedConflict;
         });
     }
 
     /**
      * Compute whether there is a conflict alongside.
      * @param lat lateral directionality
      * @return whether there is a conflict alongside
      */
     private boolean computeConflictAlongside(final LateralDirectionality lat)
     {
         try
         {
             RelativeLane lane = new RelativeLane(lat, 1);
             if (getPerception().getLaneStructure().exists(lane))
             {
                 Iterator<Entry<Conflict>> conflicts = getPerception().getLaneStructure()
                         .getUpstreamObjects(lane, Conflict.class, RelativePosition.FRONT).iterator();
                 if (conflicts.hasNext())
                 {
                     Entry<Conflict> entry = conflicts.next();
                     return entry.distance().si < entry.object().getLength().si + getGtu().getLength().si;
                 }
             }
             return false;
         }
         catch (ParameterException exception)
         {
             throw new RuntimeException("Unexpected exception while computing conflict alongside.", exception);
         }
     }
 
     @Override
     public final String toString()
     {
         return "IntersectionPerceptionChannel " + cacheAsString();
     }
 
 }