package org.opentrafficsim.trafficcontrol;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.LinkedHashMap;
   import java.util.LinkedHashSet;
   import java.util.List;
   import java.util.Map;
   import java.util.Set;
  
  import org.djunits.value.vdouble.scalar.Duration;
  import org.djutils.base.Identifiable;
  import org.djutils.event.Event;
  import org.djutils.exceptions.Throw;
  import org.djutils.immutablecollections.Immutable;
  import org.djutils.immutablecollections.ImmutableArrayList;
  import org.djutils.immutablecollections.ImmutableHashSet;
  import org.djutils.immutablecollections.ImmutableList;
  import org.djutils.immutablecollections.ImmutableMap;
  import org.djutils.immutablecollections.ImmutableSet;
  import org.opentrafficsim.base.OtsRuntimeException;
  import org.opentrafficsim.base.logger.Logger;
  import org.opentrafficsim.core.dsol.OtsSimulatorInterface;
  import org.opentrafficsim.core.network.Network;
  import org.opentrafficsim.road.network.lane.object.trafficlight.TrafficLight;
  import org.opentrafficsim.road.network.lane.object.trafficlight.TrafficLightColor;
  
  import nl.tudelft.simulation.dsol.SimRuntimeException;
  
  /**
   * Fixed time traffic light control.
   * <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>
   */
  public class FixedTimeController extends AbstractTrafficController
  {
  
      /** Cycle time. */
      private final Duration cycleTime;
  
      /** Offset. */
      private final Duration offset;
  
      /** Signal groups, for cloning. */
      private final Set<SignalGroup> signalGroups;
  
      /**
       * Constructor for fixed time traffic controller.
       * @param id id
       * @param simulator simulator
       * @param network network
       * @param offset off set from simulation start time
       * @param cycleTime cycle time
       * @param signalGroups signal groups
       * @throws SimRuntimeException simulator is past zero time
       */
      public FixedTimeController(final String id, final OtsSimulatorInterface simulator, final Network network,
              final Duration cycleTime, final Duration offset, final Set<SignalGroup> signalGroups) throws SimRuntimeException
      {
          super(id, simulator);
          Throw.whenNull(simulator, "Simulator may not be null.");
          Throw.whenNull(network, "Network may not be null.");
          Throw.whenNull(cycleTime, "Cycle time may not be null.");
          Throw.whenNull(offset, "Offset may not be null.");
          Throw.whenNull(signalGroups, "Signal groups may not be null.");
          Throw.when(cycleTime.le0(), IllegalArgumentException.class, "Cycle time must be positive.");
          // Throw.when(signalGroups.isEmpty(), IllegalArgumentException.class, "Signal groups may not be empty.");
          /*- This is no longer considered an error
          for (SignalGroup signalGroup1 : signalGroups)
          {
              for (SignalGroup signalGroup2 : signalGroups)
              {
                  if (!signalGroup1.equals(signalGroup2))
                  {
                      Throw.when(!ImmutableCollections.disjoint(signalGroup1.trafficLightIds, signalGroup2.trafficLightIds),
                              IllegalArgumentException.class, "A traffic light is in both signal group %s and signal group %s.",
                              signalGroup1.getId(), signalGroup2.getId());
                  }
              }
          }
          */
          this.cycleTime = cycleTime;
          this.offset = offset;
          this.signalGroups = new LinkedHashSet<>(signalGroups); // make a copy so we can modify it.
          mergeGreenPhasesInNewSignalGroups();
          // Schedule setup at time == 0 (when the network should be fully created and all traffic lights have been constructed)
          simulator.scheduleEventAbs(Duration.ZERO, () -> setup(simulator, network));
      }
  
      /**
       * This method finds traffic lights that are present in multiple signal groups, extracts them from their existing groups,
       * and places them in a new signal group that allows the traffic light to be green whenever any of the original signal
       * groups did.
       */
     private void mergeGreenPhasesInNewSignalGroups()
     {
         // Identify traffic lights that are present in more than one signal group
         Map<String, List<SignalGroup>> signalGroupsOfTrafficLight = new LinkedHashMap<>();
         for (SignalGroup sg : this.signalGroups)
         {
             for (String trafficLightId : sg.getTrafficLightIds())
             {
                 List<SignalGroup> sgList = signalGroupsOfTrafficLight.get(trafficLightId);
                 if (null == sgList)
                 {
                     sgList = new ArrayList<>();
                     signalGroupsOfTrafficLight.put(trafficLightId, sgList);
                 }
                 sgList.add(sg);
             }
         }
         // Collect all flanks that persist for nonzero duration
         int nextNumber = 0;
         for (String trafficLightId : signalGroupsOfTrafficLight.keySet())
         {
             List<SignalGroup> sgList = signalGroupsOfTrafficLight.get(trafficLightId);
             if (sgList.size() > 1)
             {
                 // Check for overlapping or adjacent green phases
                 List<Flank> flanks = new ArrayList<>();
                 for (SignalGroup sg : sgList)
                 {
                     double sgOffset = sg.getOffset().si;
                     double preGreenDuration = sg.getPreGreen().si;
                     if (preGreenDuration > 0)
                     {
                         flanks.add(new Flank(sgOffset % this.cycleTime.si, TrafficLightColor.PREGREEN));
                         sgOffset += preGreenDuration;
                     }
                     flanks.add(new Flank(sgOffset % this.cycleTime.si, TrafficLightColor.GREEN));
                     sgOffset += sg.getGreen().si;
                     double yellowDuration = sg.getYellow().si;
                     if (yellowDuration > 0)
                     {
                         flanks.add(new Flank(sgOffset % this.cycleTime.si, TrafficLightColor.YELLOW));
                         sgOffset += yellowDuration;
                     }
                     flanks.add(new Flank(sgOffset % this.cycleTime.si, TrafficLightColor.RED));
                 }
                 Collections.sort(flanks);
                 boolean combined = false;
                 int greenCount = 0;
                 for (int index = 0; index < flanks.size(); index++)
                 {
                     Flank flank = flanks.get(index);
                     TrafficLightColor nextColor = flank.getTrafficLightColor();
                     if (TrafficLightColor.GREEN == nextColor)
                     {
                         greenCount++;
                         if (greenCount > 1)
                         {
                             flanks.remove(index);
                             index--;
                             combined = true;
                             continue;
                         }
                     }
                     else if (TrafficLightColor.YELLOW == nextColor)
                     {
                         if (greenCount > 1)
                         {
                             flanks.remove(index);
                             index--;
                             continue;
                         }
                     }
                     else if (TrafficLightColor.RED == nextColor)
                     {
                         greenCount--;
                         if (greenCount > 0)
                         {
                             flanks.remove(index);
                             index--;
                             continue;
                         }
                     }
                 }
                 if (combined)
                 {
                     // Traffic light has adjacent or overlapping green realizations.
                     String newSignalGroupName = "CombinedSignalGroups_";
                     // Remove the traffic light from the current signal groups that it is part of
                     for (SignalGroup sg : sgList)
                     {
                         Logger.ots().trace("Reducing {}", sg);
                         newSignalGroupName = newSignalGroupName + "_" + sg.getId();
                         Set<String> trafficLightIds = new LinkedHashSet<>();
                         for (String tlId : sg.getTrafficLightIds())
                         {
                             if (!tlId.equals(trafficLightId))
                             {
                                 trafficLightIds.add(tlId);
                             }
                         }
                         this.signalGroups.remove(sg);
                         if (trafficLightIds.size() > 0)
                         {
                             SignalGroup newSignalGroup = new SignalGroup(sg.getId(), trafficLightIds, sg.getOffset(),
                                     sg.getPreGreen(), sg.getGreen(), sg.getYellow());
                             this.signalGroups.add(newSignalGroup);
                         }
                     }
                     // Create new signal group(s) for each green realization of the traffic light
                     Duration sgOffset = null;
                     Duration preGreen = Duration.ZERO;
                     Duration green = null;
                     Duration yellow = Duration.ZERO;
                     double cumulativeOffset = 0;
                     for (int index = 0; index < flanks.size(); index++)
                     {
                         Flank flank = flanks.get(index);
                         if (null == sgOffset)
                         {
                             sgOffset = Duration.ofSI(flank.getOffset());
                         }
                         if (TrafficLightColor.GREEN == flank.getTrafficLightColor())
                         {
                             preGreen = Duration.ofSI(flank.getOffset() - sgOffset.si);
                         }
                         if (TrafficLightColor.YELLOW == flank.getTrafficLightColor())
                         {
                             green = Duration.ofSI(flank.getOffset() - cumulativeOffset);
                         }
                         if (TrafficLightColor.RED == flank.getTrafficLightColor())
                         {
                             nextNumber++;
                             yellow = Duration.ofSI(flank.getOffset() - cumulativeOffset);
                             Set<String> trafficLightIds = new LinkedHashSet<>(1);
                             trafficLightIds.add(trafficLightId);
                             SignalGroup newSignalGroup = new SignalGroup(newSignalGroupName + "_" + nextNumber, trafficLightIds,
                                     sgOffset, preGreen, green, yellow);
                             this.signalGroups.add(newSignalGroup);
                         }
                         cumulativeOffset = flank.getOffset();
                     }
                 }
             }
         }
     }
 
     /**
      * Initiates all traffic control events.
      * @param simulator simulator
      * @param network network
      * @throws SimRuntimeException when traffic light does not exist in the network
      */
     @SuppressWarnings("unused")
     private void setup(final OtsSimulatorInterface simulator, final Network network) throws SimRuntimeException
     {
         for (SignalGroup signalGroup : this.signalGroups)
         {
             signalGroup.startup(this.offset, this.cycleTime, simulator, network);
         }
     }
 
     @Override
     public void notify(final Event event)
     {
         // nothing
     }
 
     @Override
     public String getFullId()
     {
         return getId();
     }
 
     /**
      * Return cycle time.
      * @return cycleTime.
      */
     public final Duration getCycleTime()
     {
         return this.cycleTime;
     }
 
     /**
      * Return offset duration.
      * @return offset.
      */
     public final Duration getOffset()
     {
         return this.offset;
     }
 
     /**
      * Return signal groups.
      * @return signalGroups.
      */
     public final Set<SignalGroup> getSignalGroups()
     {
         return this.signalGroups;
     }
 
     @Override
     public String toString()
     {
         return "FixedTimeController [cycleTime=" + this.cycleTime + ", offset=" + this.offset + ", signalGroups="
                 + this.signalGroups + ", full id=" + this.getFullId() + "]";
     }
 
     /**
      * Fixed time signal group. A group of traffic lights who's colors change simultaneously.
      * <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>
      */
     public static class SignalGroup implements Identifiable
     {
 
         /** Id. */
         private final String id;
 
         /** Traffic light ids. */
         private final ImmutableSet<String> trafficLightIds;
 
         /** Offset from start of cycle. */
         private final Duration offset;
 
         /** Pre-green duration. */
         private final Duration preGreen;
 
         /** Green duration. */
         private final Duration green;
 
         /** Yellow duration. */
         private final Duration yellow;
 
         /** Current color (according to <b>this</b> SignalGroup). */
         private TrafficLightColor currentColor = TrafficLightColor.RED;
 
         // The following properties are remembered for the updates after the startup
 
         /** Traffic light objects. */
         private List<TrafficLight> trafficLights;
 
         /** Simulator. */
         private OtsSimulatorInterface simulator;
 
         /** Red time. */
         private Duration red;
 
         /**
          * Constructor without pre-green duration.
          * @param id id
          * @param trafficLightIds traffic light ids
          * @param offset offset from start of cycle
          * @param green green duration
          * @param yellow yellow duration
          */
         public SignalGroup(final String id, final Set<String> trafficLightIds, final Duration offset, final Duration green,
                 final Duration yellow)
         {
             this(id, trafficLightIds, offset, Duration.ZERO, green, yellow);
         }
 
         /**
          * Constructor with pre-green duration.
          * @param id id
          * @param trafficLightIds traffic light ids
          * @param offset offset from start of cycle
          * @param preGreen pre-green duration
          * @param green green duration
          * @param yellow yellow duration
          */
         public SignalGroup(final String id, final Set<String> trafficLightIds, final Duration offset, final Duration preGreen,
                 final Duration green, final Duration yellow)
         {
             Throw.whenNull(id, "Id may not be null.");
             Throw.whenNull(trafficLightIds, "Traffic light ids may not be null.");
             Throw.whenNull(offset, "Offset may not be null.");
             Throw.whenNull(preGreen, "Pre-green may not be null.");
             Throw.when(preGreen.lt(Duration.ZERO), IllegalArgumentException.class, "Pre green duration may not be negative");
             Throw.whenNull(green, "Green may not be null.");
             Throw.when(green.lt(Duration.ZERO), IllegalArgumentException.class, "Green duration may not be negative");
             Throw.whenNull(yellow, "Yellow may not be null.");
             Throw.when(yellow.lt(Duration.ZERO), IllegalArgumentException.class, "Yellow duration may not be negative");
             Throw.when(trafficLightIds.isEmpty(), IllegalArgumentException.class, "Traffic light ids may not be empty.");
             this.id = id;
             this.trafficLightIds = new ImmutableHashSet<>(trafficLightIds, Immutable.COPY);
             this.offset = offset;
             this.preGreen = preGreen;
             this.green = green;
             this.yellow = yellow;
         }
 
         /**
          * Retrieve the id of this signal group.
          * @return String
          */
         @Override
         public String getId()
         {
             return this.id;
         }
 
         /**
          * Connect to the traffic lights in the network, initialize the traffic lights to their initial color and schedule the
          * first transitions.
          * @param controllerOffset controller offset
          * @param cycleTime cycle time
          * @param theSimulator simulator
          * @param network network
          * @throws SimRuntimeException when traffic light does not exist in the network
          */
         public void startup(final Duration controllerOffset, final Duration cycleTime, final OtsSimulatorInterface theSimulator,
                 final Network network) throws SimRuntimeException
         {
             this.simulator = theSimulator;
             double totalOffsetSI = this.offset.si + controllerOffset.si;
             while (totalOffsetSI < 0.0)
             {
                 totalOffsetSI += cycleTime.si;
             }
             Duration totalOffset = Duration.ofSI(totalOffsetSI % cycleTime.si);
             this.red = cycleTime.minus(this.preGreen).minus(this.green).minus(this.yellow);
             Throw.when(this.red.lt0(), IllegalArgumentException.class, "Cycle time shorter than sum of non-red times.");
 
             this.trafficLights = new ArrayList<>();
             ImmutableMap<String, TrafficLight> trafficLightObjects = network.getObjectMap(TrafficLight.class);
             for (String trafficLightId : this.trafficLightIds)
             {
                 TrafficLight trafficLight = trafficLightObjects.get(trafficLightId);
                 if (null == trafficLight) // Traffic light not found using id; try to find it by full id
                 {
                     // TODO: networkId.trafficLightId? Shouldn't that be linkId.trafficLightId?
                     trafficLight = trafficLightObjects.get(network.getId() + "." + trafficLightId);
                 }
                 Throw.when(trafficLight == null, SimRuntimeException.class, "Traffic light \"" + trafficLightId
                         + "\" in fixed time controller could not be found in network " + network.getId() + ".");
                 this.trafficLights.add(trafficLight);
             }
             Duration inCycleTime = Duration.ZERO.minus(totalOffset);
             while (inCycleTime.si < 0)
             {
                 inCycleTime = inCycleTime.plus(cycleTime);
             }
             Duration duration = null;
             if (inCycleTime.ge(this.preGreen.plus(this.green).plus(this.yellow)))
             {
                 this.currentColor = TrafficLightColor.RED; // redundant; it is already RED
                 duration = cycleTime.minus(inCycleTime);
             }
             else if (inCycleTime.lt(this.preGreen))
             {
                 this.currentColor = TrafficLightColor.PREGREEN;
                 duration = this.preGreen.minus(inCycleTime);
             }
             else if (inCycleTime.lt(this.preGreen.plus(this.green)))
             {
                 this.currentColor = TrafficLightColor.GREEN;
                 duration = this.preGreen.plus(this.green).minus(inCycleTime);
             }
             else if (inCycleTime.lt(this.preGreen.plus(this.green).plus(this.yellow)))
             {
                 this.currentColor = TrafficLightColor.YELLOW;
                 duration = this.preGreen.plus(this.green).plus(this.yellow).minus(inCycleTime);
             }
             else
             {
                 throw new SimRuntimeException("Cannot determine initial state of signal group " + this);
             }
             setTrafficLights(this.currentColor);
             this.simulator.scheduleEventRel(duration, () -> updateColors());
         }
 
         /**
          * Updates the color of the traffic lights.
          */
         @SuppressWarnings("unused")
         private void updateColors()
         {
             try
             {
                 Duration duration = Duration.ZERO;
                 TrafficLightColor color = this.currentColor;
                 while (duration.le0())
                 {
                     switch (color)
                     {
                         case PREGREEN:
                             color = TrafficLightColor.GREEN;
                             duration = this.green;
                             break;
                         case GREEN:
                             color = TrafficLightColor.YELLOW;
                             duration = this.yellow;
                             break;
                         case YELLOW:
                             color = TrafficLightColor.RED;
                             duration = this.red;
                             break;
                         case RED:
                             color = TrafficLightColor.PREGREEN;
                             duration = this.preGreen;
                             break;
                         default:
                             throw new OtsRuntimeException("Cannot happen.");
                     }
                 }
                 setTrafficLights(color);
                 this.simulator.scheduleEventRel(duration, () -> updateColors());
             }
             catch (SimRuntimeException exception)
             {
                 // cannot happen; we check all durations for consistency
                 throw new OtsRuntimeException(exception);
             }
         }
 
         /**
          * Change the color of our traffic lights.
          * @param trafficLightColor the new traffic light color to show
          */
         private void setTrafficLights(final TrafficLightColor trafficLightColor)
         {
             this.currentColor = trafficLightColor;
             for (TrafficLight trafficLight : this.trafficLights)
             {
                 trafficLight.setTrafficLightColor(trafficLightColor);
             }
         }
 
         @Override
         public int hashCode()
         {
             final int prime = 31;
             int result = 1;
             result = prime * result + ((this.id == null) ? 0 : this.id.hashCode());
             return result;
         }
 
         @Override
         public boolean equals(final Object obj)
         {
             if (this == obj)
             {
                 return true;
             }
             if (obj == null)
             {
                 return false;
             }
             if (getClass() != obj.getClass())
             {
                 return false;
             }
             SignalGroup other = (SignalGroup) obj;
             if (this.id == null)
             {
                 if (other.id != null)
                 {
                     return false;
                 }
             }
             else if (!this.id.equals(other.id))
             {
                 return false;
             }
             return true;
         }
 
         /**
          * Returns traffic lights.
          * @return trafficLights.
          */
         public final ImmutableList<TrafficLight> getTrafficLights()
         {
             return new ImmutableArrayList<>(this.trafficLights);
         }
 
         /**
          * Returns red duration.
          * @return red.
          */
         public final Duration getRed()
         {
             return this.red;
         }
 
         /**
          * Returns traffic light ids.
          * @return trafficLightIds.
          */
         public final ImmutableSet<String> getTrafficLightIds()
         {
             return this.trafficLightIds;
         }
 
         /**
          * Returns offset duration.
          * @return offset.
          */
         public final Duration getOffset()
         {
             return this.offset;
         }
 
         /**
          * Returns pre-green duration.
          * @return preGreen.
          */
         public final Duration getPreGreen()
         {
             return this.preGreen;
         }
 
         /**
          * Returns green duration.
          * @return green.
          */
         public final Duration getGreen()
         {
             return this.green;
         }
 
         /**
          * Returns yellow duration.
          * @return yellow.
          */
         public final Duration getYellow()
         {
             return this.yellow;
         }
 
         /**
          * Retrieve the current color of this SignalGroup.
          * @return the current color of this signal group.
          */
         public TrafficLightColor getCurrentColor()
         {
             return this.currentColor;
         }
 
         @Override
         public String toString()
         {
             return "SignalGroup [id=" + this.id + ", trafficLightIds=" + this.trafficLightIds + ", offset=" + this.offset
                     + ", preGreen=" + this.preGreen + ", green=" + this.green + ", yellow=" + this.yellow + "currentColor="
                     + this.currentColor + "]";
         }
 
     }
 
     /**
      * Storage of an offset within a cycle and the new traffic light color. Used to sort the flanks. The term 'flank' refers to
      * the 'side' of the shape of an electronic signal impulse.
      */
     class Flank implements Comparable<Flank>
     {
         /** When (in the cycle time is this transition. */
         private final double offset;
 
         /** What is the color after this transition. */
         private final TrafficLightColor newColor;
 
         /**
          * Construct a new Flank.
          * @param offset offset within the cycle time
          * @param newColor color to show after this transition
          */
         Flank(final double offset, final TrafficLightColor newColor)
         {
             this.offset = offset;
             this.newColor = newColor;
         }
 
         /**
          * Retrieve the offset.
          * @return the offset
          */
         public double getOffset()
         {
             return this.offset;
         }
 
         /**
          * Retrieve the color after this transition.
          * @return the color after this transition
          */
         public TrafficLightColor getTrafficLightColor()
         {
             return this.newColor;
         }
 
         @Override
         public String toString()
         {
             return "Flank [offset=" + this.offset + ", newColor=" + this.newColor + "]";
         }
 
         /** Cumulative rounding errors are less than this value and traffic light transitions are spaced further apart. */
         private static final double COMPARE_MARGIN = 0.01;
 
         @Override
         public int compareTo(final Flank o)
         {
             double deltaOffset = this.offset - o.offset;
             if (Math.abs(deltaOffset) < COMPARE_MARGIN)
             {
                 deltaOffset = 0;
             }
             if (deltaOffset > 0)
             {
                 return 1;
             }
             if (deltaOffset < 0)
             {
                 return -1;
             }
             if (TrafficLightColor.GREEN == this.newColor && TrafficLightColor.GREEN != o.newColor)
             {
                 return -1;
             }
             if (TrafficLightColor.GREEN == o.newColor && TrafficLightColor.GREEN != this.newColor)
             {
                 return 1;
             }
             return 0;
         }
 
     }
 
 }