import java.util.Random;

public class NetworkHost
{
    // This constant controls the maximum size of the buffer in a Message
    // and in a Packet
    public static final int MAXDATASIZE = 20;

    
    private int entity;
    private int traceLevel;
    private EventList eventList;
    private Random rand;
    private double time;
    private double lossProb;
    private double corruptProb;
    private String receivedData;   
    private int numberDelivered;
 
    // Default versions of methods to implement. 
    protected void Output(Message message)
    {
         System.out.println("Output method called for entity" + entity 
                             + "but not implemented.");
    }

    protected void Input(Packet packet)
    {
         System.out.println("Input method called for entity" + entity 
                             + "but not implemented.");
    }

    protected void TimerInterrupt()
    {
         System.out.println("TimerInterupt method called for entity" + entity 
                             + "but not implemented.");
    }

    protected void Init()
    {
         System.out.println("Init method called for entity" + entity
                             + "but not implemented.");
    }


    

    public NetworkHost(int entityName,
                       EventList events,
                       double pLoss,
                       double pCorrupt,
                       int trace,
                       Random random)
    {
        entity = entityName;
        eventList = events;
        lossProb = pLoss;
        corruptProb = pCorrupt;
        traceLevel = trace;
        rand = random;
        time = 0.0;
        receivedData = "";
        numberDelivered = 0;
    }
    
    
    protected final void stopTimer()
    {
        if (traceLevel > 0)
        {
            System.out.println("stopTimer: stopping timer at " + time);
        }

        Event timer = eventList.removeTimer(entity);

        // Let the student know they are attempting to cancel a non-existant 
        // timer
        if (timer == null)
        {
            System.out.println("stopTimer: Warning: Unable to cancel your " +
                               "timer");
        }        
    }
    
    protected final void startTimer(double increment)
    {
        if (traceLevel > 0)
        {
            System.out.println("startTimer: starting timer at " + time);
        }

        Event t = eventList.removeTimer(entity);        

        if (t != null)
        {
            System.out.println("startTimer: Warning: Attempting to start a " +
                               "timer that is already running");
            eventList.add(t);
            return;
        }
        else
        {
            Event timer = new Event(time + increment,
                                    NetworkSimulator.TIMERINTERRUPT, entity);
            eventList.add(timer);
        }
    }    
    
    protected final void udtSend(Packet p)
    {
        int destination;
        double arrivalTime;
        Packet packet = new Packet(p);
    
        if (traceLevel > 0)
        {
            System.out.println("udtSend: " + packet);
        }

        // Set our destination
        if (entity == NetworkSimulator.A)
        {
            destination = NetworkSimulator.B;
        }
        else if (entity == NetworkSimulator.B)
        {
            destination = NetworkSimulator.A;
        }
        else
        {
            System.out.println("udtSend: Warning: invalid packet sender");
            return;
        }

        // Simulate losses
        if (rand.nextDouble() < lossProb)
        {
            if (traceLevel > 0)
            {
                System.out.println("udtSend: packet being lost");
            }
            
            return;
        }
        
        // Simulate corruption
        if (rand.nextDouble() < corruptProb)
        {
            if (traceLevel > 0)
            {
                System.out.println("udtSend: packet being corrupted");
            }
            
            double x = rand.nextDouble();
            if (x < 0.75)
            {
                String payload = packet.getPayload();
                
                if (payload.length()<2){
                	payload = "=";
                }
                else{
                    //payload = "?" + payload.substring(payload.length() - 1);
                    payload = "=" + payload.substring(1);
              	
                }
                 
                packet.setPayload(payload);
            }
            else if (x < 0.875)
            {
                packet.setSeqnum(Math.abs(rand.nextInt()));
            }
            else
            {
                packet.setAcknum(Math.abs(rand.nextInt()));
            }
        }
        
        // Decide when the packet will arrive.  Since the medium cannot
        // reorder, the packet will arrive 1 to 10 time units after the
        // last packet sent by this sender
        arrivalTime = eventList.getLastPacketTime(destination);
        
        if (arrivalTime <= 0.0)
        {
            arrivalTime = time;
        }
        
        //arrivalTime = arrivalTime + 1.0 + (rand.nextDouble() * 19.0);
        arrivalTime = arrivalTime + 1.0 + Math.abs(5.0*rand.nextGaussian()+9.0);

        // Finally, create and schedule this event
        if (traceLevel > 2)
        {
            System.out.println("udtSend: Scheduling arrival on other side");
        }
        Event arrival = new Event(arrivalTime, NetworkSimulator.FROMNETWORK, destination, packet);
        eventList.add(arrival);
    }
    
    protected final void deliverData(String dataSent)
    {
        // FOR TESTING
        if (entity == NetworkSimulator.B){
            receivedData = receivedData + "DATA:" + dataSent+"\n" ;
            numberDelivered = numberDelivered + 1;
        }
        if (traceLevel > 0)
        {
            System.out.print("deliverData: data received at "+entity + ":");
            System.out.println(dataSent);

        }
    }
    
    protected void setTime(double newtime)
    {
        time=newtime;
    }

    protected double getTime()
    {
        return time;
    }

    protected String getReceivedData()
    {
        return receivedData;
    }
    
    protected int getNumberDelivered()
    {
        return numberDelivered;
    }
    
    protected void printEventList()
    {
        System.out.println(eventList.toString());
    }
    
}