package org.opentrafficsim.road.gtu.lane.perception.object;
   
   import java.util.Optional;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.djunits.value.vdouble.scalar.Speed;
   import org.djutils.exceptions.Try;
   import org.opentrafficsim.base.geometry.OtsLine2d;
   import org.opentrafficsim.road.gtu.lane.LaneBasedGtu;
  import org.opentrafficsim.road.gtu.lane.perception.PerceptionCollectable;
  import org.opentrafficsim.road.gtu.lane.perception.categories.neighbors.PerceivedGtuType;
  import org.opentrafficsim.road.network.lane.CrossSectionLink;
  import org.opentrafficsim.road.network.lane.Lane;
  import org.opentrafficsim.road.network.lane.conflict.Conflict;
  import org.opentrafficsim.road.network.lane.conflict.ConflictPriority;
  import org.opentrafficsim.road.network.lane.conflict.ConflictRule;
  import org.opentrafficsim.road.network.lane.conflict.ConflictType;
  
  /**
   * Interface for perceived {@code Conflict} objects. A standard implementation is provided under {@code of(...)} which wraps a
   * {@code Conflict} and returns most values as is.
   * <p>
   * Copyright (c) 2024-2024 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 <a href="https://github.com/averbraeck">Alexander Verbraeck</a>
   * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
   */
  public interface PerceivedConflict extends PerceivedLaneBasedObject
  {
  
      /**
       * Returns the conflict type.
       * @return conflict type
       */
      ConflictType getConflictType();
  
      /**
       * Returns whether this is a crossing conflict.
       * @return whether this is a crossing conflict
       */
      boolean isCrossing();
  
      /**
       * Returns whether this is a merge conflict.
       * @return whether this is a merge conflict
       */
      boolean isMerge();
  
      /**
       * Returns whether this is a split conflict.
       * @return whether this is a split conflict
       */
      boolean isSplit();
  
      /**
       * Returns the conflict priority.
       * @return conflict priority
       */
      ConflictPriority getConflictPriority();
  
      /**
       * Returns the length of the conflict on the conflicting lane.
       * @return length of the conflict on the conflicting lane
       */
      Length getConflictingLength();
  
      /**
       * Returns a set of conflicting GTU's upstream of the <i>start</i> of the conflict ordered close to far from the conflict.
       * @return set of conflicting GTU's upstream of the <i>start</i> of the conflict ordered close to far from the conflict
       */
      PerceptionCollectable<PerceivedGtu, LaneBasedGtu> getUpstreamConflictingGTUs();
  
      /**
       * Returns a set of conflicting GTU's downstream of the <i>start</i> of the conflict ordered close to far from the conflict.
       * Distance is given relative to the <i>end</i> of the conflict, or null for conflicting vehicles on the conflict. In the
       * latter case the overlap is used.
       * @return set of conflicting GTU's downstream of the <i>start</i> of the conflict ordered close to far from the conflict
       */
      PerceptionCollectable<PerceivedGtu, LaneBasedGtu> getDownstreamConflictingGTUs();
  
      /**
       * Returns the visibility on the conflicting lane within which conflicting vehicles are visible. All upstream conflicting
       * GTUs have a distance smaller than the visibility. Depending on a limited visibility, a certain (lower) speed may be
       * required while approaching the conflict.
       * @return visibility on the conflicting lane within which conflicting vehicles are visible
       */
      Length getConflictingVisibility();
  
      /**
       * Returns the speed limit on the conflicting lane.
       * @return speed limit on the conflicting lane
       */
      Speed getConflictingSpeedLimit();
  
      /**
       * Returns the conflicting link.
       * @return the conflicting link
       */
     CrossSectionLink getConflictingLink();
 
     /**
      * Returns the stop line.
      * @return stop line
      */
     PerceivedObject getStopLine();
 
     /**
      * Returns the stop line on the conflicting lane.
      * @return stop line
      */
     PerceivedObject getConflictingStopLine();
 
     /**
      * Returns the conflict rule type.
      * @return conflict rule type
      */
     Class<? extends ConflictRule> getConflictRuleType();
 
     /**
      * Returns the distance of a traffic light upstream on the conflicting lane.
      * @return distance of a traffic light upstream on the conflicting lane, empty if no traffic light
      */
     Optional<Length> getConflictingTrafficLightDistance();
 
     /**
      * Whether the conflict is permitted by the traffic light.
      * @return whether the conflict is permitted by the traffic light
      */
     boolean isPermitted();
 
     /**
      * Returns the width at the given fraction.
      * @param fraction fraction from 0 to 1
      * @return width at the given fraction
      */
     Length getWidthAtFraction(double fraction);
 
     /**
      * Returns a standard implementation of this interface that wraps a {@code Conflict} and uses a given perceived GTU type to
      * perceive the upstream and downstream GTUs.
      * @param perceivingGtu perceiving GTU
      * @param conflict conflict to perceive
      * @param perceivedGtuType perceived GTU type
      * @param distance distance from perceiving GTU to conflict
      * @param conflictingVisibility visibility range at other conflict
      * @return perceived conflict
      */
     @SuppressWarnings("methodlength")
     static PerceivedConflict of(final LaneBasedGtu perceivingGtu, final Conflict conflict,
             final PerceivedGtuType perceivedGtuType, final Length distance, final Length conflictingVisibility)
     {
         final Kinematics kinematics = Kinematics.staticAhead(distance);
         // TODO stop lines (current models happen not to use this, but should be possible)
         final PerceivedObject stopLine =
                 new PerceivedObjectBase("stopLineId", ObjectType.STOPLINE, Length.ZERO, Kinematics.staticAhead(Length.ZERO));
         final PerceivedObject conflictingStopLine = new PerceivedObjectBase("conflictingStopLineId", ObjectType.STOPLINE,
                 Length.ZERO, Kinematics.staticAhead(Length.ZERO));
         final Speed conflictingSpeedLimit = Try.assign(() -> conflict.getOtherConflict().getLane().getHighestSpeedLimit(),
                 "Unable to obtain higest speed limit on conflicting lane.");
         final Length conflictingTrafficLightDistance =
                 conflict.getOtherConflict().getTrafficLightDistance(conflictingVisibility);
 
         final PerceptionCollectable<PerceivedGtu, LaneBasedGtu> upstreamConflictingGTUs =
                 conflict.getOtherConflict().getUpstreamGtus(perceivingGtu, perceivedGtuType, conflictingVisibility);
         final PerceptionCollectable<PerceivedGtu, LaneBasedGtu> downstreamConflictingGTUs =
                 conflict.getOtherConflict().getDownstreamGtus(perceivingGtu, perceivedGtuType, conflictingVisibility);
 
         Length pos1a = conflict.getLongitudinalPosition();
         Length pos2a = conflict.getOtherConflict().getLongitudinalPosition();
         Length pos1b = Length.min(pos1a.plus(conflict.getLength()), conflict.getLane().getLength());
         Length pos2b = Length.min(pos2a.plus(conflict.getOtherConflict().getLength()),
                 conflict.getOtherConflict().getLane().getLength());
         OtsLine2d line1 = conflict.getLane().getCenterLine();
         OtsLine2d line2 = conflict.getOtherConflict().getLane().getCenterLine();
         double dStart = line1.getLocation(pos1a).distance(line2.getLocation(pos2a));
         double dEnd = line1.getLocation(pos1b).distance(line2.getLocation(pos2b));
         double startWidth = dStart + .5 * conflict.getLane().getWidth(pos1a).si
                 + .5 * conflict.getOtherConflict().getLane().getWidth(pos2a).si;
         double endWidth = dEnd + .5 * conflict.getLane().getWidth(pos1b).si
                 + .5 * conflict.getOtherConflict().getLane().getWidth(pos2b).si;
 
         return new PerceivedConflict()
         {
             @Override
             public Lane getLane()
             {
                 return conflict.getLane();
             }
 
             @Override
             public ObjectType getObjectType()
             {
                 return ObjectType.CONFLICT;
             }
 
             @Override
             public Length getLength()
             {
                 return conflict.getLength();
             }
 
             @Override
             public Kinematics getKinematics()
             {
                 return kinematics;
             }
 
             @Override
             public String getId()
             {
                 return conflict.getId();
             }
 
             @Override
             public ConflictType getConflictType()
             {
                 return conflict.getConflictType();
             }
 
             @Override
             public boolean isCrossing()
             {
                 return conflict.getConflictType().isCrossing();
             }
 
             @Override
             public boolean isMerge()
             {
                 return conflict.getConflictType().isMerge();
             }
 
             @Override
             public boolean isSplit()
             {
                 return conflict.getConflictType().isSplit();
             }
 
             @Override
             public ConflictPriority getConflictPriority()
             {
                 return conflict.conflictPriority();
             }
 
             @Override
             public Length getConflictingLength()
             {
                 return conflict.getOtherConflict().getLength();
             }
 
             @Override
             public PerceptionCollectable<PerceivedGtu, LaneBasedGtu> getUpstreamConflictingGTUs()
             {
                 return upstreamConflictingGTUs;
             }
 
             @Override
             public PerceptionCollectable<PerceivedGtu, LaneBasedGtu> getDownstreamConflictingGTUs()
             {
                 return downstreamConflictingGTUs;
             }
 
             @Override
             public Length getConflictingVisibility()
             {
                 return conflictingVisibility;
             }
 
             @Override
             public Speed getConflictingSpeedLimit()
             {
                 return conflictingSpeedLimit;
             }
 
             @Override
             public CrossSectionLink getConflictingLink()
             {
                 return conflict.getOtherConflict().getLane().getLink();
             }
 
             @Override
             public PerceivedObject getStopLine()
             {
                 return stopLine;
             }
 
             @Override
             public PerceivedObject getConflictingStopLine()
             {
                 return conflictingStopLine;
             }
 
             @Override
             public Class<? extends ConflictRule> getConflictRuleType()
             {
                 return conflict.getConflictRule().getClass();
             }
 
             @Override
             public Optional<Length> getConflictingTrafficLightDistance()
             {
                 return Optional.of(conflictingTrafficLightDistance);
             }
 
             @Override
             public boolean isPermitted()
             {
                 return conflict.isPermitted();
             }
 
             @Override
             public Length getWidthAtFraction(final double fraction)
             {
                 return Length.ofSI((1.0 - fraction) * startWidth + fraction * endWidth);
             }
         };
     }
 
 }