package org.opentrafficsim.trafficcontrol.ccol;
   
   import java.io.BufferedReader;
   import java.io.IOException;
   import java.io.InputStreamReader;
   import java.io.PrintWriter;
   import java.io.Serializable;
   import java.net.ServerSocket;
   import java.net.Socket;
  import java.rmi.RemoteException;
  import java.util.Set;
  
  import org.djunits.unit.DurationUnit;
  import org.djunits.value.vdouble.scalar.Duration;
  import org.djunits.value.vdouble.scalar.Time;
  import org.djutils.event.EventInterface;
  import org.djutils.event.EventProducer;
  import org.djutils.event.EventType;
  import org.opentrafficsim.core.dsol.OTSSimulatorInterface;
  import org.opentrafficsim.core.network.Network;
  import org.opentrafficsim.core.network.NetworkException;
  import org.opentrafficsim.core.object.InvisibleObjectInterface;
  import org.opentrafficsim.road.network.lane.object.sensor.TrafficLightSensor;
  import org.opentrafficsim.road.network.lane.object.trafficlight.TrafficLight;
  import org.opentrafficsim.trafficcontrol.ActuatedTrafficController;
  import org.opentrafficsim.trafficcontrol.TrafficControlException;
  
  import nl.tudelft.simulation.dsol.SimRuntimeException;
  import nl.tudelft.simulation.dsol.simtime.SimTimeDoubleUnit;
  import nl.tudelft.simulation.dsol.simulators.DEVSSimulator;
  import nl.tudelft.simulation.dsol.simulators.SimulatorInterface;
  
  /**
   * Communication link with a CCOL traffic control program.
   * <p>
   * Copyright (c) 2013-2020 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/node/13">OpenTrafficSim License</a>.
   * <p>
   * @version $Revision$, $LastChangedDate$, by $Author$, initial version Jan 23, 2017 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   * @author <a href="http://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   */
  public class CCOL extends EventProducer implements ActuatedTrafficController
  {
      /** */
      private static final long serialVersionUID = 20170126L;
  
      /** Name of this CCOL traffic controller. */
      final String id;
  
      /** The simulator. */
      final DEVSSimulator<Time, Duration, SimTimeDoubleUnit> simulator;
  
      /** TCP port for incoming connection. */
      static int PORT = 4321;
  
      /** The evaluation interval of a CCOL controller. */
      final static Duration EVALUATION_INTERVAL = new Duration(0.1, DurationUnit.SECOND);
  
      /** Socket used to listen for the incoming connection from the CCOL controller. */
      ServerSocket serverSocket;
  
      /** Socket for communication with the CCOL controller. */
      private Socket clientSocket = null;
  
      /** Receives data from the CCOL process. */
      private BufferedReader ccolReader = null;
  
      /** Sends data to the CCOL process. */
      private PrintWriter ccolWriter = null;
  
      /** Thread that blocks until accept returns. */
      Thread acceptThread;
  
      /**
       * Construct a new CCOL communication link.
       * @param id String; id of the traffic controller
       * @param controlProgram String; name of the CCOL program that this CCOL link must communicate with
       * @param trafficLights Set&lt;TrafficLight&gt;; the traffic lights. The ids of the traffic lights must end with two digits
       *            that match the stream numbers as used in the traffic control program
       * @param sensors Set&lt;TrafficLightSensor&gt;; the traffic sensors. The ids of the traffic sensors must end with three
       *            digits; the first two of those must match the stream and sensor numbers used in the traffic control program
       * @param simulator DEVSSimulator&lt;Time, Duration, SimTimeDoubleUnit&gt;; the simulation engine
       * @throws TrafficControlException on failure to initialize the connection to the external CCOL program
       * @throws SimRuntimeException on failure to schedule the first evaluation event
       */
      public CCOL(final String id, final String controlProgram, final Set<TrafficLight> trafficLights,
              final Set<TrafficLightSensor> sensors, final DEVSSimulator<Time, Duration, SimTimeDoubleUnit> simulator)
              throws TrafficControlException, SimRuntimeException
      {
          this.id = id;
          this.simulator = simulator;
          try
          {
              // Set up a listening socket
              this.serverSocket = new ServerSocket(PORT);
              Runnable acceptTask = new Runnable()
              {
                 @Override
                 public void run()
                 {
                     try
                     {
                         setClientSocket(CCOL.this.serverSocket.accept());
                     }
                     catch (IOException exception)
                     {
                         exception.printStackTrace();
                     }
                 }
             };
             this.acceptThread = new Thread(acceptTask);
             this.acceptThread.start();
             // Start up the external CCOL program
             Runtime.getRuntime().exec(controlProgram + " localhost:" + this.serverSocket.getLocalPort());
         }
         catch (IOException e)
         {
             e.printStackTrace();
         }
         this.simulator.scheduleEventRel(Duration.ZERO, this, this, "step", null);
         this.simulator.addListener(this, SimulatorInterface.END_REPLICATION_EVENT);
     }
 
     /**
      * Set the client socket (called from the accept thread).
      * @param socket Socket; the socket returned by accept
      */
     void setClientSocket(final Socket socket)
     {
         if (null != this.clientSocket)
         {
             System.err.println("clientSocket already set");
             return;
         }
         this.clientSocket = socket;
         try
         {
             this.ccolReader = new BufferedReader(new InputStreamReader(this.clientSocket.getInputStream()));
             this.ccolWriter = new PrintWriter(this.clientSocket.getOutputStream());
         }
         catch (IOException exception)
         {
             exception.printStackTrace();
         }
         // Close the server socket to release resources and ensure that we cannot accept further connections
         try
         {
             this.serverSocket.close();
         }
         catch (IOException exception)
         {
             exception.printStackTrace();
         }
     }
 
     /**
      * Retrieve the client socket for shutdown.
      * @return Socket; the socket for communication with the CCOL client
      */
     Socket getClientSocket()
     {
         return this.clientSocket;
     }
 
     /**
      * Let the CCOL engine determine the new state of the traffic lights and update the traffic lights accordingly.
      * @throws TrafficControlException when the CCOL engine reports an error or communication with the CCOL engine fails
      * @throws SimRuntimeException when scheduling the next evaluation fails
      */
     @SuppressWarnings("unused")
     private void step() throws TrafficControlException, SimRuntimeException
     {
         // TODO time should be formatted as date, hour, etc.
         String message = String.format("STEP %s", this.simulator.getSimulatorTime());
         this.ccolWriter.print(message);
         try
         {
             String result = this.ccolReader.readLine();
             // TODO parse the result and update the state of traffic lights accordingly
             // Protocol must ensure that we know it when all updates have been received.
         }
         catch (IOException exception)
         {
             exception.printStackTrace();
         }
         // Schedule the next step.
         this.simulator.scheduleEventRel(EVALUATION_INTERVAL, this, this, "step", null);
     }
 
     /** {@inheritDoc} */
     @Override
     public void notify(EventInterface event) throws RemoteException
     {
         EventType eventType = event.getType();
         if (eventType.equals(SimulatorInterface.END_REPLICATION_EVENT))
         {
             if (null != this.serverSocket)
             {
                 try
                 {
                     this.serverSocket.close();
                 }
                 catch (IOException exception)
                 {
                     exception.printStackTrace();
                 }
                 this.serverSocket = null;
             }
             if (null != this.clientSocket)
             {
                 try
                 {
                     this.clientSocket.close();
                 }
                 catch (IOException exception)
                 {
                     exception.printStackTrace();
                 }
                 this.clientSocket = null;
             }
         }
         // Tracing etc. not implemented yet.
     }
 
     /** {@inheritDoc} */
     @Override
     public String getId()
     {
         return this.id;
     }
 
     /** {@inheritDoc} */
     @Override
     public String getFullId()
     {
         return this.id;
     }
 
     /** {@inheritDoc} */
     @Override
     public void updateDetector(final String detectorId, final boolean detectingGTU)
     {
         // FIXME: format of messages is TBD
         String message = String.format("DET %s %s", detectorId, detectingGTU);
         this.ccolWriter.print(message);
     }
 
     /** {@inheritDoc} */
     @Override
     public InvisibleObjectInterface clone(OTSSimulatorInterface newSimulator, Network newNetwork) throws NetworkException
     {
         // FIXME: implement the clone() for CCOL
         return null;
     }
 
     /** {@inheritDoc} */
     @Override
     public Serializable getSourceId()
     {
         return "CCOL";
     }
 
 }