package org.opentrafficsim.road.gtu.tactical.lmrs;
   
   import java.util.Optional;
   
   import org.djunits.unit.LengthUnit;
   import org.djunits.value.vdouble.scalar.Acceleration;
   import org.djunits.value.vdouble.scalar.Duration;
   import org.djunits.value.vdouble.scalar.Length;
   import org.opentrafficsim.base.parameters.ParameterException;
  import org.opentrafficsim.core.gtu.GtuException;
  import org.opentrafficsim.core.gtu.Stateless;
  import org.opentrafficsim.road.gtu.perception.FilteredIterable;
  import org.opentrafficsim.road.gtu.perception.PerceptionCollectable;
  import org.opentrafficsim.road.gtu.perception.RelativeLane;
  import org.opentrafficsim.road.gtu.perception.categories.BusStopPerception;
  import org.opentrafficsim.road.gtu.perception.object.PerceivedBusStop;
  import org.opentrafficsim.road.gtu.tactical.TacticalContextEgo;
  import org.opentrafficsim.road.gtu.tactical.pt.BusSchedule;
  import org.opentrafficsim.road.gtu.tactical.util.CarFollowingUtil;
  import org.opentrafficsim.road.network.object.BusStop;
  
  /**
   * Bus stop acceleration incentive.
   * <p>
   * Copyright (c) 2013-2026 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 Alexander Verbraeck
   * @author Peter Knoppers
   * @author Wouter Schakel
   */
  public final class AccelerationBusStop implements AccelerationIncentive, Stateless<AccelerationIncentive>
  {
  
      /** Distance within which the bus can open the doors. */
      // TODO this process is much more complex: tail blocking other traffic? other bus in front? many people at bus stop?
      private static final Length STOP_DISTANCE = new Length(15.0, LengthUnit.SI);
  
      /** Singleton instance. */
      public static final AccelerationBusStop SINGLETON = new AccelerationBusStop();
  
      @Override
      public AccelerationBusStop get()
      {
          return SINGLETON;
      }
  
      /**
       * Constructor.
       */
      private AccelerationBusStop()
      {
          //
      }
  
      @Override
      @SuppressWarnings("checkstyle:parameternumber")
      public Acceleration accelerate(final TacticalContextEgo context, final RelativeLane lane, final Length mergeDistance)
              throws ParameterException, GtuException
      {
          PerceptionCollectable<PerceivedBusStop, BusStop> stops =
                  context.getPerception().getPerceptionCategory(BusStopPerception.class).getBusStops();
          if (stops.isEmpty())
          {
              return NO_REASON;
          }
          BusSchedule busSchedule = (BusSchedule) context.getRoute().orElseThrow(
                  () -> new GtuException("Unable to determine acceleration for bus stops for bus without bus schedule."));
          Duration now = context.getTime();
          Iterable<PerceivedBusStop> it = lane.isCurrent() ? stops : new FilteredIterable<>(stops, (busStop) ->
          {
              return busStop.getDistance().gt(mergeDistance);
          });
          for (PerceivedBusStop stop : it)
          {
              String busStopId = stop.getId();
              if (busSchedule.isLineStop(busStopId, now))
              {
  
                  // check when to leave
                  boolean stoppedAtStop =
                          stop.getRelativeLane().isCurrent() && stop.getDistance().le(STOP_DISTANCE) && context.getSpeed().eq0();
                  if (busSchedule.getActualDepartureBusStop(busStopId).isEmpty())
                  {
                      if (stoppedAtStop)
                      {
                          // bus just stopped
                          Duration departureTime = now.plus(busSchedule.getDwellTime(busStopId));
                          if (busSchedule.isForceSchedule(busStopId))
                          {
                              departureTime = Duration.max(departureTime, busSchedule.getDepartureTime(busStopId));
                          }
                          busSchedule.setActualDeparture(busStopId, stop.getConflictIds(), departureTime);
                      }
                  }
  
                  // stop if not known yet, or before departure time
                  Optional<Duration> actualDeparture = busSchedule.getActualDepartureBusStop(busStopId);
                  if (actualDeparture.isEmpty() || now.lt(actualDeparture.get()))
                 {
                     if (stoppedAtStop)
                     {
                         // stand still at location where stop was initiated
                         return Acceleration.ZERO;
                     }
                     else
                     {
                         // decelerate to initiate stop
                         return CarFollowingUtil.stop(context, stop.getDistance());
                     }
                 }
             }
         }
         return NO_REASON;
     }
 
     @Override
     public String toString()
     {
         return "AccelerationBusStop";
     }
 
 }