package org.opentrafficsim.kpi.sampling;
   
   import java.util.ArrayList;
   import java.util.Iterator;
   import java.util.List;
   
   import org.djunits.value.vdouble.scalar.Duration;
   import org.djunits.value.vdouble.scalar.Length;
   import org.djutils.exceptions.Throw;
  import org.opentrafficsim.kpi.interfaces.GtuData;
  import org.opentrafficsim.kpi.interfaces.LaneData;
  
  /**
   * Contains all trajectories pertaining to a certain space-time region.
   * <p>
   * Copyright (c) 2013-2024 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/peter-knoppers">Peter Knoppers</a>
   * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
   * @param <G> GTU data type
   */
  public class TrajectoryGroup<G extends GtuData> implements Iterable<Trajectory<G>>
  {
  
      /** Start time of trajectories. */
      private final Duration startTime;
  
      /** Start position of the section. */
      private final Length startPosition;
  
      /** End position of the section. */
      private final Length endPosition;
  
      /** Lane for which the trajectories have been sampled. */
      private final LaneData<?> lane;
  
      /** Trajectories. */
      private final List<Trajectory<G>> trajectories = new ArrayList<>();
  
      /**
       * Constructor without length specification. The complete lane will be used.
       * @param startTime start time of trajectories
       * @param lane lane
       */
      public TrajectoryGroup(final Duration startTime, final LaneData<?> lane)
      {
          this(startTime, Length.ZERO, lane == null ? null : lane.getLength(), lane);
      }
  
      /**
       * Constructor.
       * @param startTime start time of trajectory group
       * @param startPosition start position
       * @param endPosition end position
       * @param lane the lane
       */
      public TrajectoryGroup(final Duration startTime, final Length startPosition, final Length endPosition,
              final LaneData<?> lane)
      {
          Throw.whenNull(startTime, "Start time may not be null.");
          // keep before position check; prevents "End position may not be null" due to missing direction in other constructor
          Throw.whenNull(lane, "Lane time may not be null.");
          Throw.whenNull(startPosition, "Start position may not be null");
          Throw.whenNull(endPosition, "End position may not be null");
          Throw.when(startPosition.gt(endPosition), IllegalArgumentException.class,
                  "Start position should be smaller than end position in the direction of travel");
          this.startTime = startTime;
          this.startPosition = startPosition;
          this.endPosition = endPosition;
          this.lane = lane;
      }
  
      /**
       * Add trajectory.
       * @param trajectory trajectory to add
       */
      public final synchronized void addTrajectory(final Trajectory<G> trajectory)
      {
          this.trajectories.add(trajectory);
      }
  
      /**
       * Returns the start time.
       * @return start time
       */
      public final Duration getStartTime()
      {
          return this.startTime;
      }
  
      /**
       * Returns the length.
       * @return length
       */
      public final Length getLength()
      {
          return this.endPosition.minus(this.startPosition);
     }
 
     /**
      * Whether this {@code TrajectoryGroup} holds the given trajectory. Note that this is false if the given trajectory is
      * derived from a trajectory in this {@code TrajectoryGroup} (e.g. a subset of).
      * @param trajectory trajectory
      * @return whether this {@code TrajectoryGroup} holds the given trajectory.
      */
     public final boolean contains(final Trajectory<?> trajectory)
     {
         return this.trajectories.contains(trajectory);
     }
 
     /**
      * Returns the number of trajectories in this group.
      * @return number of trajectories in this group
      */
     public final int size()
     {
         return this.trajectories.size();
     }
 
     /**
      * Returns a list of trajectories.
      * @return list of trajectories
      */
     public final List<Trajectory<G>> getTrajectories()
     {
         return new ArrayList<>(this.trajectories);
     }
 
     /**
      * Returns trajectory group between two locations.
      * @param x0 start length
      * @param x1 end length
      * @return list of trajectories
      */
     public final synchronized TrajectoryGroup<G> getTrajectoryGroup(final Length x0, final Length x1)
     {
         Length minLenght = Length.max(x0, this.startPosition);
         Length maxLenght = Length.min(x1, this.endPosition);
         TrajectoryGroup<G> out = new TrajectoryGroup<>(this.startTime, minLenght, maxLenght, this.lane);
         for (Trajectory<G> trajectory : this.trajectories)
         {
             Trajectory<G> sub = trajectory.subSet(x0, x1);
             if (sub.size() > 0)
             {
                 out.addTrajectory(sub);
             }
         }
         return out;
     }
 
     /**
      * Returns trajectory group between two times.
      * @param t0 start time
      * @param t1 end time
      * @return list of trajectories
      */
     public final synchronized TrajectoryGroup<G> getTrajectoryGroup(final Duration t0, final Duration t1)
     {
         TrajectoryGroup<G> out = new TrajectoryGroup<>(this.startTime.lt(t0) ? t0 : this.startTime, this.lane);
         for (Trajectory<G> trajectory : this.trajectories)
         {
             Trajectory<G> sub = trajectory.subSet(t0, t1);
             if (sub.size() > 0)
             {
                 out.addTrajectory(sub);
             }
         }
         return out;
     }
 
     /**
      * Returns trajectory group between two locations and between two times.
      * @param x0 start length
      * @param x1 end length
      * @param t0 start time
      * @param t1 end time
      * @return list of trajectories
      */
     public final synchronized TrajectoryGroup<G> getTrajectoryGroup(final Length x0, final Length x1, final Duration t0,
             final Duration t1)
     {
         TrajectoryGroup<G> out = new TrajectoryGroup<>(this.startTime.lt(t0) ? t0 : this.startTime, this.lane);
         for (Trajectory<G> trajectory : this.trajectories)
         {
             out.addTrajectory(trajectory.subSet(x0, x1, t0, t1));
         }
         return out;
     }
 
     /**
      * Returns the lane.
      * @return lane
      */
     public final LaneData<?> getLane()
     {
         return this.lane;
     }
 
     @Override
     public final int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = prime * result + this.lane.hashCode();
         result = prime * result + this.endPosition.hashCode();
         result = prime * result + this.startPosition.hashCode();
         result = prime * result + this.startTime.hashCode();
         result = prime * result + this.trajectories.hashCode();
         return result;
     }
 
     @Override
     public final boolean equals(final Object obj)
     {
         if (this == obj)
         {
             return true;
         }
         if (obj == null)
         {
             return false;
         }
         if (getClass() != obj.getClass())
         {
             return false;
         }
         TrajectoryGroup<?> other = (TrajectoryGroup<?>) obj;
         if (!this.lane.equals(other.lane))
         {
             return false;
         }
         if (!this.endPosition.equals(other.endPosition))
         {
             return false;
         }
         if (!this.startPosition.equals(other.startPosition))
         {
             return false;
         }
         if (!this.startTime.equals(other.startTime))
         {
             return false;
         }
         if (!this.trajectories.equals(other.trajectories))
         {
             return false;
         }
         return true;
     }
 
     @Override
     public final String toString()
     {
         return "TrajectoryGroup [startTime=" + this.startTime + ", minLength=" + this.startPosition + ", maxLength="
                 + this.endPosition + ", lane=" + this.lane + ", collected "
                 + (this.trajectories == null ? "null" : this.trajectories.size()) + " trajectories]";
     }
 
     @Override
     public Iterator<Trajectory<G>> iterator()
     {
         return this.trajectories.iterator();
     }
 
 }