package org.opentrafficsim.sim0mq.publisher;
   
   import org.djutils.exceptions.Throw;
   import org.djutils.immutablecollections.ImmutableList;
   import org.djutils.metadata.MetaData;
   import org.djutils.metadata.ObjectDescriptor;
   import org.djutils.serialization.SerializationException;
   import org.opentrafficsim.core.gtu.Gtu;
   import org.opentrafficsim.core.network.Link;
  import org.opentrafficsim.core.network.Network;
  import org.opentrafficsim.road.gtu.lane.LaneBasedGtu;
  import org.opentrafficsim.road.network.lane.CrossSectionElement;
  import org.opentrafficsim.road.network.lane.CrossSectionLink;
  import org.opentrafficsim.road.network.lane.Lane;
  import org.sim0mq.Sim0MQException;
  
  /**
   * Transceiver for the ids of the GTUs on a link.
   * <p>
   * Copyright (c) 2020-2024 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>
   */
  public class LaneGtuIdTransceiver extends AbstractTransceiver
  {
      /** The network. */
      private final Network network;
  
      /**
       * Construct a GtuIdTransceiver.
       * @param network the OTS network
       */
      public LaneGtuIdTransceiver(final Network network)
      {
          super("Lane GTU id transceiver",
                  new MetaData("Link id, lane id", "Link id, lane id",
                          new ObjectDescriptor[] {new ObjectDescriptor("Link id", "Link id", String.class),
                                  new ObjectDescriptor("Lane id", "Lane id", String.class)}),
                  new MetaData("String array", "String array filled with all currently valid GTU ids on the lane",
                          new ObjectDescriptor[] {new ObjectDescriptor("String array",
                                  "String array filled with all currently valid GTU ids on the lane", String[].class)}));
          Throw.whenNull(network, "Network may not be null");
          this.network = network;
      }
  
      @Override
      public final Object[] get(final Object[] address, final ReturnWrapper returnWrapper)
              throws Sim0MQException, SerializationException
      {
          String bad = verifyMetaData(getAddressFields(), address);
          if (bad != null)
          {
              returnWrapper.nack("Bad address; need id of a link and id of a CrossSectionElement");
              return null;
          }
          Link link = this.network.getLink((String) address[0]);
          if (null == link || (!(link instanceof CrossSectionLink)))
          {
              returnWrapper.nack("Network does not contain a link with id " + address[0]);
              return null;
          }
          CrossSectionLink csl = (CrossSectionLink) link;
          CrossSectionElement cse = csl.getCrossSectionElement((String) address[1]);
          if (null == cse)
          {
              returnWrapper.nack("Link " + address[0] + " does not contain a cross section element with id " + address[1]);
              return null;
          }
          if (!(cse instanceof Lane))
          {
              returnWrapper.nack("CrossSectionElement " + address[1] + " of link with id " + address[0] + ", is not a lane");
              return null;
          }
          Lane lane = (Lane) cse;
          ImmutableList<LaneBasedGtu> gtus = lane.getGtuList();
          Object[] result = new Object[gtus.size()];
          int nextIndex = 0;
          for (Gtu gtu : gtus)
          {
              result[nextIndex++] = gtu.getId();
          }
          return result;
      }
  
      @Override
      public String toString()
      {
          return "LaneGtuIdTransceiver [network=" + this.network + ", super=" + super.toString() + "]";
      }
  
  }