package erlang1;

import java.util.Vector;

/**
 *
 * @author Mav
 */
public class ErlangNetwork {
    private float offeredTraffic;
    private int servers;
    private float[] occupiedProbability;

    ErlangNetwork()
    {
        offeredTraffic = 0;
        servers = 0;
    }

    ErlangNetwork(int arrivalRate, int serviceRate, int servers)
    {
        offeredTraffic = (float)arrivalRate/serviceRate;
        this.servers = servers;
        occupiedProbability = new float[servers+1];
        calcOccupiedProbability();
    }

    ErlangNetwork(float offeredTraffic, int servers)
    {
        this.offeredTraffic = offeredTraffic;
        this.servers = servers;
        occupiedProbability = new float[servers+1];
        calcOccupiedProbability();
    }

    private void calcOccupiedProbability()
    {
        float temp = 0;
        for(int i = 0; i < servers; i++)
        {
            temp += (java.lang.Math.pow(offeredTraffic,i)/factorial(i));
        }
        for(int i = 0;i<=servers;i++)
        {
            occupiedProbability[i] = (float) (java.lang.Math.pow(offeredTraffic,i)/factorial(i))/temp;
        }

    }

    //Function to get the factorial of n.
    private int factorial(int n)
    {
        int factVal = 1;
        for (int i=1; i<=n; i++)
        {
            factVal = factVal * i;
        }
        return factVal;
    }

    //Function to get the occupied probability for a certain state.
    float getOccupiedProbability(int state)
    {
        if( state <= servers )
            return occupiedProbability[state];
        else
            return -1; //If the state is outwith the range -1 is returned.
    }
}