package net.berack.upo.valpre.bcnn;

import net.berack.upo.valpre.bcnn.simutil.*;
import net.berack.upo.valpre.bcnn.simutil.Queue;

import java.util.*;
class Sim {

    // Class Sim variables
    public static double Clock, MeanInterArrivalTime, MeanServiceTime, SIGMA, LastEventTime,
            TotalBusy, MaxQueueLength, SumResponseTime;
    public static long  NumberOfCustomers, QueueLength, NumberInService,
            TotalCustomers, NumberOfDepartures, LongService;

    public final static int arrival = 1;
    public final static int departure = 2;

    public static EventList FutureEventList;
    public static Queue Customers;
    public static Random stream;

    public static void main(String argv[]) {

        MeanInterArrivalTime = 4.5; MeanServiceTime = 3.2;
        SIGMA                = 0.6; TotalCustomers  = 1000;
        long seed            = Long.parseLong(argv[0]);

        stream = new Random(seed);           // initialize rng stream
        FutureEventList = new EventList();
        Customers = new Queue();

        Initialization();

        // Loop until first "TotalCustomers" have departed
        while(NumberOfDepartures < TotalCustomers ) {
            Event evt = (Event)FutureEventList.getMin();  // get imminent event
            FutureEventList.dequeue();                    // be rid of it
            Clock = evt.get_time();                       // advance simulation time
            if( evt.get_type() == arrival ) ProcessArrival(evt);
            else  ProcessDeparture(evt);
        }
        ReportGeneration();
    }

    // seed the event list with TotalCustomers arrivals
    public static void Initialization()   {
        Clock = 0.0;
        QueueLength = 0;
        NumberInService = 0;
        LastEventTime = 0.0;
        TotalBusy = 0 ;
        MaxQueueLength = 0;
        SumResponseTime = 0;
        NumberOfDepartures = 0;
        LongService = 0;

        // create first arrival event
        Event evt = new Event(arrival, exponential( stream, MeanInterArrivalTime));
        FutureEventList.enqueue( evt );
    }

    public static void ProcessArrival(Event evt) {
        Customers.enqueue(evt);
        QueueLength++;
        // if the server is idle, fetch the event, do statistics
        // and put into service
        if( NumberInService == 0) ScheduleDeparture();
        else TotalBusy += (Clock - LastEventTime);  // server is busy

        // adjust max queue length statistics
        if (MaxQueueLength < QueueLength) MaxQueueLength = QueueLength;

        // schedule the next arrival
        Event next_arrival = new Event(arrival, Clock+exponential(stream, MeanInterArrivalTime));
        FutureEventList.enqueue( next_arrival );
        LastEventTime = Clock;
    }

    public static void ScheduleDeparture() {
        double ServiceTime;
        // get the job at the head of the queue
        while (( ServiceTime = normal(stream, MeanServiceTime, SIGMA)) < 0 );
        Event depart = new Event(departure,Clock+ServiceTime);
        FutureEventList.enqueue( depart );
        NumberInService = 1;
        QueueLength--;
    }

    public static void ProcessDeparture(Event e) {
        // get the customer description
        Event finished = (Event) Customers.dequeue();
        // if there are customers in the queue then schedule
        // the departure of the next one
        if( QueueLength > 0 ) ScheduleDeparture();
        else NumberInService = 0;
        // measure the response time and add to the sum
        double response = (Clock - finished.get_time());
        SumResponseTime += response;
        if( response > 4.0 ) LongService++; // record long service
        TotalBusy += (Clock - LastEventTime );
        NumberOfDepartures++;
        LastEventTime = Clock;
    }

    public static void ReportGeneration() {
        double RHO   = TotalBusy/Clock;
        double AVGR  = SumResponseTime/TotalCustomers;
        double PC4   = ((double)LongService)/TotalCustomers;


        System.out.println( "SINGLE SERVER QUEUE SIMULATION - GROCERY STORE CHECKOUT COUNTER ");
        System.out.println( "\tMEAN INTERARRIVAL TIME                         "
                + MeanInterArrivalTime );
        System.out.println( "\tMEAN SERVICE TIME                              "
                + MeanServiceTime );
        System.out.println( "\tSTANDARD DEVIATION OF SERVICE TIMES            " + SIGMA );
        System.out.println( "\tNUMBER OF CUSTOMERS SERVED                     " + TotalCustomers );
        System.out.println();
        System.out.println( "\tSERVER UTILIZATION                             " + RHO );
        System.out.println( "\tMAXIMUM LINE LENGTH                            " + MaxQueueLength );
        System.out.println( "\tAVERAGE RESPONSE TIME                          " + AVGR + "  MINUTES" );
        System.out.println( "\tPROPORTION WHO SPEND FOUR ");
        System.out.println( "\t MINUTES OR MORE IN SYSTEM                     " + PC4 );
        System.out.println( "\tSIMULATION RUNLENGTH                           " + Clock + " MINUTES" );
        System.out.println( "\tNUMBER OF DEPARTURES                           " + TotalCustomers );
    }

    public static double exponential(Random rng, double mean) {
        return -mean*Math.log( rng.nextDouble() );
    }

    public static double SaveNormal;
    public static int  NumNormals = 0;
    public static final double  PI = 3.1415927 ;

    public static double normal(Random rng, double mean, double sigma) {
        double ReturnNormal;
        // should we generate two normals?
        if(NumNormals == 0 ) {
            double r1 = rng.nextDouble();
            double r2 = rng.nextDouble();
            ReturnNormal = Math.sqrt(-2*Math.log(r1))*Math.cos(2*PI*r2);
            SaveNormal   = Math.sqrt(-2*Math.log(r1))*Math.sin(2*PI*r2);
            NumNormals = 1;
        } else {
            NumNormals = 0;
            ReturnNormal = SaveNormal;
        }
        return ReturnNormal*sigma + mean ;
    }
}