package org.opentrafficsim.kpi.sampling;
   
   import java.io.Serializable;
   import java.util.Iterator;
   import java.util.LinkedHashSet;
   import java.util.Set;
   
   import org.djutils.exceptions.Throw;
   import org.djutils.immutablecollections.ImmutableIterator;
  import org.opentrafficsim.kpi.interfaces.LaneData;
  import org.opentrafficsim.kpi.interfaces.LinkData;
  
  /**
   * A cross sections contains locations on lanes that together make up a cross section. It is not required that this is on a
   * single road, i.e. the cross section may any section in space.
   * <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://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
   * @author <a href="https://github.com/wjschakel">Wouter Schakel</a>
   */
  public class CrossSection implements Serializable
  {
  
      /** */
      private static final long serialVersionUID = 20160929L;
  
      /** Set of lane locations. */
      private final Set<LanePosition> lanePositions;
  
      /**
       * Constructor with set of lane positions.
       * @param lanePositions Set&lt;LanePosition&gt;; set of lane locations
       */
      public CrossSection(final Set<LanePosition> lanePositions)
      {
          Throw.whenNull(lanePositions, "Lane positions may not be null.");
          this.lanePositions = new LinkedHashSet<>(lanePositions);
      }
  
      /**
       * Constructor with link and fraction.
       * @param link LinkData&lt;?&gt;; link
       * @param fraction double; fraction on link
       * @throws SamplingException if an input is null
       */
      public CrossSection(final LinkData<?> link, final double fraction) throws SamplingException
      {
          Throw.whenNull(link, "Link lane positions may not be null.");
          this.lanePositions = new LinkedHashSet<>();
          for (LaneData<?> lane : link.getLaneDatas())
          {
              LanePosition lanePosition = new LanePosition(lane, lane.getLength().times(fraction));
              this.lanePositions.add(lanePosition);
          }
      }
  
      /**
       * Returns the number of lane positions.
       * @return number of directed lane positions
       */
      public final int size()
      {
          return this.lanePositions.size();
      }
  
      /**
       * Returns a safe copy of the lane positions.
       * @return safe copy of lane positions
       */
      public final Set<LanePosition> getLanePositions()
      {
          return new LinkedHashSet<>(this.lanePositions);
      }
  
      /**
       * Returns an iterator over the lane positions.
       * @return iterator over lane positions
       */
      public final Iterator<LanePosition> getIterator()
      {
          return new ImmutableIterator<>(this.lanePositions.iterator());
      }
  
      /** {@inheritDoc} */
      @Override
      @SuppressWarnings("checkstyle:designforextension")
      public String toString()
      {
          return "CrossSection [lanePositions=" + this.lanePositions + "]";
      }
  
  }