package org.opentrafficsim.road.gtu.lane.perception;
   
   import java.util.ArrayList;
   import java.util.List;
   import java.util.Map;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.opentrafficsim.core.gtu.GTUDirectionality;
   import org.opentrafficsim.core.gtu.GTUType;
  import org.opentrafficsim.road.network.lane.Lane;
  
  /**
   * A light-weight wrapper for LaneRecord search tools (PerceptionIterator). This is suitable for situations where parts of the
   * network not in the LaneStructure need to be perceived, such as conflicting lanes at intersection conflicts. Searches can only
   * be simple upstream or downstream searches, without lateral movement and without regard of a route. This class should not be
   * used whenever the LaneStructure can be used, as this class builds up a new tree each time step.
   * <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 19 feb. 2018 <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 LaneDirectionRecord implements LaneRecord<LaneDirectionRecord>
  {
  
      /** Lane. */
      private final Lane lane;
  
      /** Direction of travel. */
      private final GTUDirectionality dir;
  
      /** Distance to start. */
      private final Length startDistance;
  
      /** GTU type. */
      private final GTUType gtuType;
  
      /** Stored next lanes. */
      private List<LaneDirectionRecord> next;
  
      /** Stored prev lanes. */
      private List<LaneDirectionRecord> prev;
  
      /**
       * Constructor.
       * @param lane Lane; lane
       * @param dir GTUDirectionality; direction of travel
       * @param startDistance Length; distance to start
       * @param gtuType GTUType; GTU type
       */
      public LaneDirectionRecord(final Lane lane, final GTUDirectionality dir, final Length startDistance, final GTUType gtuType)
      {
          this.lane = lane;
          this.dir = dir;
          this.startDistance = startDistance;
          this.gtuType = gtuType;
      }
  
      /** {@inheritDoc} */
      @Override
      public List<LaneDirectionRecord> getNext()
      {
          if (this.next == null)
          {
              Map<Lane, GTUDirectionality> map = this.lane.downstreamLanes(this.dir, this.gtuType);
              this.next = new ArrayList<>();
              Length distance = this.startDistance.plus(getLength());
              for (Lane down : map.keySet())
              {
                  this.next.add(new LaneDirectionRecord(down, map.get(down), distance, this.gtuType));
              }
          }
          return this.next;
      }
  
      /** {@inheritDoc} */
      @Override
      public List<LaneDirectionRecord> getPrev()
      {
          if (this.prev == null)
          {
              Map<Lane, GTUDirectionality> map = this.lane.upstreamLanes(this.dir, this.gtuType);
              this.prev = new ArrayList<>();
              for (Lane up : map.keySet())
              {
                  this.prev.add(new LaneDirectionRecord(up, map.get(up), this.startDistance.minus(up.getLength()), this.gtuType));
              }
          }
          return this.prev;
      }
  
      /** {@inheritDoc} */
      @Override
      public Length getStartDistance()
      {
          return this.startDistance;
     }
 
     /** {@inheritDoc} */
     @Override
     public Length getLength()
     {
         return this.lane.getLength();
     }
 
     /** {@inheritDoc} */
     @Override
     public GTUDirectionality getDirection()
     {
         return this.dir;
     }
 
     /** {@inheritDoc} */
     @Override
     public Lane getLane()
     {
         return this.lane;
     }
 
 }