package org.opentrafficsim.road.network.lane.conflict;
   
   import java.util.Map;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.djutils.exceptions.Throw;
   import org.opentrafficsim.core.gtu.GTUDirectionality;
   import org.opentrafficsim.core.gtu.GTUException;
   import org.opentrafficsim.core.gtu.GTUType;
  import org.opentrafficsim.core.gtu.RelativePosition;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTU;
  import org.opentrafficsim.road.network.lane.CrossSectionLink.Priority;
  import org.opentrafficsim.road.network.lane.Lane;
  
  import nl.tudelft.simulation.dsol.simulators.SimulatorInterface;
  
  /**
   * Conflict rule for conflicts where busses enter the lane after a stop.
   * <p>
   * Copyright (c) 2013-2019 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 27 jan. 2017 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class BusStopConflictRule implements ConflictRule
  {
  
      /** Simulator. */
      private final SimulatorInterface.TimeDoubleUnit simulator;
  
      /**
       * Constructor.
       * @param simulator SimulatorInterface.TimeDoubleUnit; simulator
       */
      public BusStopConflictRule(final SimulatorInterface.TimeDoubleUnit simulator)
      {
          this.simulator = simulator;
      }
  
      /** {@inheritDoc} */
      @Override
      public ConflictPriority determinePriority(final Conflict conflict)
      {
  
          // determine if we request from bus stop, or not
          boolean requestingFromBusStop;
          Conflict busConflict;
          // conflict builder enforces that only one of the two links has priority BUS_STOP
          if (conflict.getLane().getParentLink().getPriority().equals(Priority.BUS_STOP))
          {
              Throw.when(conflict.getOtherConflict().getLane().getParentLink().getPriority().equals(Priority.BUS_STOP),
                      IllegalArgumentException.class,
                      "BusStopConflictRule does not support a conflict between two links with priority BUS_STOP.");
              requestingFromBusStop = true;
              busConflict = conflict;
          }
          else
          {
              requestingFromBusStop = false;
              busConflict = conflict.getOtherConflict();
          }
  
          // find bus and determine if it has priority
          // conflict forces that LongitudinalDirection is DIR_PLUS or DIR_MINUS
          Lane lane = busConflict.getLane();
          GTUDirectionality dir =
                  busConflict.getDirection().isForward() ? GTUDirectionality.DIR_PLUS : GTUDirectionality.DIR_MINUS;
          Length pos = busConflict.getLongitudinalPosition();
          LaneBasedGTU gtu = null;
          try
          {
              while (gtu == null && lane != null)
              {
                  gtu = lane.getGtuBehind(pos, dir, RelativePosition.FRONT, this.simulator.getSimulatorTime());
                  if (gtu == null)
                  {
                      Map<Lane, GTUDirectionality> map = lane.upstreamLanes(dir, GTUType.BUS);
                      if (map.size() == 1)
                      {
                          lane = map.keySet().iterator().next();
                          // only on bus stop
                          if (lane.getParentLink().getPriority().isBusStop())
                          {
                              dir = map.get(lane);
                              pos = dir.isPlus() ? lane.getLength() : Length.ZERO;
                          }
                          else
                          {
                              lane = null;
                          }
                      }
                      else
                      {
                          lane = null;
                      }
                  }
             }
         }
         catch (GTUException exception)
         {
             throw new RuntimeException("Error while looking for GTU upstream of merge at bus stop.", exception);
         }
         boolean busHasPriority = gtu != null && gtu.getGTUType().isOfType(GTUType.BUS) && gtu.getTurnIndicatorStatus().isLeft();
 
         // if bus has priority and bus is asking, PRIORITY
         // if bus has no priority and bus is not asking (i.e. car is asking), PRIORITY
         return busHasPriority == requestingFromBusStop ? ConflictPriority.PRIORITY : ConflictPriority.YIELD;
 
     }
 
     /** {@inheritDoc} */
     @Override
     public final ConflictRule clone(final SimulatorInterface.TimeDoubleUnit newSimulator)
     {
         return new BusStopConflictRule(newSimulator);
     }
 
     /** {@inheritDoc} */
     @Override
     public final String toString()
     {
         return "BusStopConflictRule";
     }
 
 }