package foo.bar.baz.units;

import java.io.Serializable;

public class Energy implements Serializable
{
    private static final long serialVersionUID = 1L;

    public enum Unit { MMBTU, KWHR }

    private static final double MMBTU_PER_KWHR = 0.0034095106405145;
    private Unit displayUnit = Unit.MMBTU;

    private double mmbtu = 0;

    public static Energy fromMMBTU(double mmbtu)
    {
        Energy energy = new Energy();
        energy.setMMBTU(mmbtu);
        return energy;
    }

    public static Energy fromKWHR(double kwhr)
    {
        Energy energy = new Energy();
        energy.setKWHR(kwhr);
        return energy;
    }

    public void setMMBTU(double mmbtu)
    {
        this.mmbtu = mmbtu;
    }

    public void setKWHR(double kwhr)
    {
        setMMBTU(kwhr * MMBTU_PER_KWHR);
    }

    public double getMMBTU()
    {
        return mmbtu;
    }

    public double getKWHR()
    {
        return mmbtu / MMBTU_PER_KWHR;
    }

    public double getEnergy(Unit unit)
    {
        switch(unit)
        {
            case MMBTU:
                return getMMBTU();
            case KWHR:
                return getKWHR();
        }
        throw new UnsupportedOperationException("Unit type not implemented");
    }

    public Unit getDisplayUnit()
    {
        return displayUnit;
    }

    public void setDisplayUnit(Unit displayUnit)
    {
        this.displayUnit = displayUnit;
    }

}