package org.opentrafficsim.road.gtu.perception.mental.channel;
   
   import java.util.Iterator;
   import java.util.NoSuchElementException;
   import java.util.Set;
   import java.util.function.Function;
   
   import org.djunits.value.vdouble.scalar.Length;
   import org.opentrafficsim.base.DistancedObject;
  import org.opentrafficsim.base.OtsRuntimeException;
  import org.opentrafficsim.base.parameters.ParameterException;
  import org.opentrafficsim.base.parameters.ParameterTypeDouble;
  import org.opentrafficsim.base.parameters.ParameterTypeLength;
  import org.opentrafficsim.road.gtu.LaneBasedGtu;
  import org.opentrafficsim.road.gtu.perception.LanePerception;
  import org.opentrafficsim.road.gtu.perception.RelativeLane;
  import org.opentrafficsim.road.gtu.perception.categories.neighbors.NeighborsPerception;
  import org.opentrafficsim.road.gtu.perception.mental.AbstractTask;
  import org.opentrafficsim.road.gtu.tactical.util.lmrs.LmrsParameters;
  
  /**
   * Task demand for potential cut-in or cooperation. This is defined as the maximum value of {@code d*(1-s/x0)} where {@code d}
   * is lane change desire towards the ego lane of any leader in either the left or right adjacent lane, {@code s} is the distance
   * to the leader with lane change desire and {@code x0} is the look-ahead distance.
   * <p>
   * Copyright (c) 2024-2026 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 Wouter Schakel
   */
  public final class ChannelTaskCooperation extends AbstractTask implements ChannelTask
  {
  
      /** Distance discount range. */
      public static final ParameterTypeLength X0_D = ChannelMental.X0_D;
  
      /** Standard set of left and right cooperation task. */
      private static final Set<ChannelTask> SET = Set.of(new ChannelTaskCooperation(true), new ChannelTaskCooperation(false));
  
      /** Standard supplier that supplies instances for left and right cooperation task. */
      public static final Function<LanePerception, Set<ChannelTask>> SUPPLIER = (p) -> SET;
  
      /** Whether this task instance regards the left side. */
      private final boolean left;
  
      /**
       * Constructor.
       * @param left whether this task instance regards the left side.
       */
      private ChannelTaskCooperation(final boolean left)
      {
          super("cooperation");
          this.left = left;
      }
  
      @Override
      public String getId()
      {
          return this.left ? "cooperation (left)" : "cooperation (right)";
      }
  
      @Override
      public Object getChannel()
      {
          return this.left ? LEFT : RIGHT;
      }
  
      @Override
      public double calculateTaskDemand(final LanePerception perception)
      {
          NeighborsPerception neighbors = perception.getPerceptionCategoryOptional(NeighborsPerception.class)
                  .orElseThrow(() -> new NoSuchElementException("NeighborsPerception not present."));
          Iterator<DistancedObject<LaneBasedGtu>> leaders =
                  neighbors.getLeaders(this.left ? RelativeLane.LEFT : RelativeLane.RIGHT).underlyingWithDistance();
          ParameterTypeDouble param = this.left ? LmrsParameters.DRIGHT : LmrsParameters.DLEFT;
          Length x0 = perception.getGtu().getParameters().getOptionalParameter(X0_D)
                  .orElseThrow(() -> new OtsRuntimeException("Parameter x0_d not present."));
          double dMax = 0.0;
          while (leaders.hasNext())
          {
              DistancedObject<LaneBasedGtu> leader = leaders.next();
              if (leader.distance().gt(x0))
              {
                  break;
              }
              double d;
              try
              {
                  d = leader.object().getParameters().getParameter(param) * (1.0 - leader.distance().si / x0.si);
                  dMax = Math.max(dMax, d);
              }
              catch (ParameterException ex)
              {
                  // leader does not provide lane change desire, ignore
              }
          }
          return Math.min(0.999, dMax);
      }
  
 }