package org.opentrafficsim.road.gtu.lane.tactical;
   
   import java.util.Set;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.opentrafficsim.base.parameters.ParameterException;
   import org.opentrafficsim.base.parameters.ParameterTypes;
   import org.opentrafficsim.core.gtu.plan.tactical.TacticalPlanner;
   import org.opentrafficsim.core.network.Link;
  import org.opentrafficsim.core.network.Node;
  import org.opentrafficsim.core.network.route.Route;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGTU;
  import org.opentrafficsim.road.gtu.lane.perception.LanePerception;
  import org.opentrafficsim.road.gtu.lane.tactical.following.CarFollowingModel;
  import org.opentrafficsim.road.network.lane.LaneDirection;
  
  /**
   * <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/docs/license.html">OpenTrafficSim License</a>.
   * </p>
   * $LastChangedDate: 2015-07-24 02:58:59 +0200 (Fri, 24 Jul 2015) $, @version $Revision: 1147 $, by $Author: averbraeck $,
   * initial version May 27, 2016 <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 interface LaneBasedTacticalPlanner extends TacticalPlanner<LaneBasedGTU, LanePerception>
  {
      /**
       * Returns the car-following model.
       * @return car following model
       */
      CarFollowingModel getCarFollowingModel();
  
      /**
       * Selects a lane from a possible set. This set contains all viable lanes in to which a lanes splits.
       * @param lanes Set&lt;LaneDirection&gt;; set of lane directions possible
       * @return LaneDirection; preferred lane direction
       * @throws ParameterException in case of a missing parameter
       */
      default LaneDirection chooseLaneAtSplit(final Set<LaneDirection> lanes) throws ParameterException
      {
          Route route = getGtu().getStrategicalPlanner().getRoute();
          if (route == null)
          {
              // select right-most lane
              LaneDirection rightMost = null;
              for (LaneDirection lane : lanes)
              {
                  rightMost = rightMost == null ? lane : rightMost(rightMost, lane);
              }
              return rightMost;
          }
          Length maxDistance = Length.NEGATIVE_INFINITY;
          LaneDirection best = null;
          for (LaneDirection lane : lanes)
          {
              LaneDirection next = lane.getNextLaneDirection(getGtu());
              if (next != null)
              {
                  Length okDistance = okDistance(next, lane.getLength(), route,
                          getGtu().getParameters().getParameter(ParameterTypes.PERCEPTION));
                  if (maxDistance.eq(okDistance))
                  {
                      best = rightMost(best, lane);
                  }
                  else if (okDistance.gt(maxDistance))
                  {
                      maxDistance = okDistance;
                      best = lane;
                  }
              }
          }
          return best;
      }
  
      /**
       * Helper method for default chooseLaneAtSplit implementation that returns the distance from this lane onwards where the
       * route can be followed.
       * @param lane LaneDirection; lane and direction
       * @param distance Length; distance so far
       * @param route Route; route
       * @param maxDistance Length; max search distance
       * @return Length; distance from this lane onwards where the route can be followed
       */
      // TODO private when we use java 9
      default Length okDistance(final LaneDirection lane, final Length distance, final Route route, final Length maxDistance)
      {
          if (distance.gt(maxDistance))
          {
              return maxDistance;
          }
          LaneDirection next = lane.getNextLaneDirection(getGtu());
          if (next == null)
          {
              Node endNode = lane.getDirection().isPlus() ? lane.getLane().getParentLink().getEndNode()
                      : lane.getLane().getParentLink().getStartNode();
              Set<Link> links = endNode.getLinks().toSet();
             links.remove(lane.getLane().getParentLink());
             if (route.contains(endNode) && (links.isEmpty() || links.iterator().next().getLinkType().isConnector()))
             {
                 // dead-end link, must be destination
                 return maxDistance;
             }
             // there is no next lane on the route, return the distance to the end of this lane
             return distance.plus(lane.getLength());
         }
         return okDistance(next, distance.plus(lane.getLength()), route, maxDistance);
     }
 
     /**
      * Returns the right-most of two lanes.
      * @param lane1 LaneDirection; lane 1
      * @param lane2 LaneDirection; lane 2
      * @return LaneDirection; right-most of two lanes
      */
     // TODO private when we use java 9
     default LaneDirection rightMost(final LaneDirection lane1, final LaneDirection lane2)
     {
         Length offset1 = lane1.getLane().getDesignLineOffsetAtBegin().plus(lane1.getLane().getDesignLineOffsetAtEnd());
         offset1 = lane1.getDirection().isPlus() ? offset1 : offset1.neg();
         Length offset2 = lane2.getLane().getDesignLineOffsetAtBegin().plus(lane2.getLane().getDesignLineOffsetAtEnd());
         offset2 = lane2.getDirection().isPlus() ? offset2 : offset2.neg();
         return offset1.lt(offset2) ? lane1 : lane2;
     }
 
 }