package Project.Arithmetic;

public class RationalNumber {
    private int numerator, denominator;
    //---------------------------------------------------------------------------------------------
    //  Constructor: Sets up the rational number by ensuring a nonzero denominator and making only
    //  the numerator signed.
    //---------------------------------------------------------------------------------------------
    public RationalNumber (int numer, int denom)
    {
        if (denom == 0)
            denom = 1;
        // Make the numerator "store" the sign
        if (denom < 0)
        {
            numer = numer * -1;
            denom = denom * -1;
        }
        numerator = numer;
        denominator = denom;
        reduce();
    }

    //---------------------------------------------------------------------------------------------
    //  Returns the numerator of this rational number.
    //---------------------------------------------------------------------------------------------
    public int getNumerator ()
    {
        return numerator;
    }

    //---------------------------------------------------------------------------------------------
    //  Returns the denominator of this rational number.
    //---------------------------------------------------------------------------------------------
    public int getDenominator ()
    {
        return denominator;
    }

    //---------------------------------------------------------------------------------------------
    //  Returns the reciprocal of this rational number.
    //---------------------------------------------------------------------------------------------
    public RationalNumber reciprocal ()
    {
        return new RationalNumber (denominator, numerator);
    }

    //---------------------------------------------------------------------------------------------
    //  Adds this rational number to the one passed as a parameter. A common denominator is found
    //  by multiplying the individual denominators.
    //---------------------------------------------------------------------------------------------
    public RationalNumber add (RationalNumber op2)
    {
        int commonDenominator = denominator * op2.getDenominator();
        int numerator1 = numerator * op2.getDenominator();
        int numerator2 = op2.getNumerator() * denominator;
        int sum = numerator1 + numerator2;

        return new RationalNumber (sum, commonDenominator);
    }

    //---------------------------------------------------------------------------------------------
    //  Subtracts the rational number passed as a parameter from this rational number.
    //---------------------------------------------------------------------------------------------
    public RationalNumber subtract (RationalNumber op2)
    {
        int commonDenominator = denominator * op2.getDenominator();
        int numerator1 = numerator * op2.getDenominator();
        int numerator2 = op2.getNumerator() * denominator;
        int difference = numerator1 - numerator2;

        return new RationalNumber (difference, commonDenominator);
    }

    //---------------------------------------------------------------------------------------------
    // Multiplies this rational number by the one passed as a parameter.
    //---------------------------------------------------------------------------------------------
    public RationalNumber multiply (RationalNumber op2)
    {
        int numer = numerator * op2.getNumerator();
        int denom = denominator * op2.getDenominator();

        return new RationalNumber (numer, denom);
    }

    //---------------------------------------------------------------------------------------------
    //  Divides this rational number by the one passed as a parameter by multiplying by the
    //  reciprocal of the second rational.
    //---------------------------------------------------------------------------------------------
    public RationalNumber divide (RationalNumber op2)
    {
        return multiply (op2.reciprocal());
    }

    //---------------------------------------------------------------------------------------------
    //  Determines if this rational number is equal to the one passed as a parameter. Assume they
    //  are both reduced.
    //---------------------------------------------------------------------------------------------
    public boolean isLike (RationalNumber op2)
    {
        return ( numerator == op2.getNumerator() &&
                denominator == op2.getDenominator() );
    }

    //---------------------------------------------------------------------------------------------
    //  Returns this rational number as a string.
    //---------------------------------------------------------------------------------------------
    public String toString ()
    {
        String result;

        if (numerator == 0) {
            result = "0";
        }
        else {
            if (denominator == 1)
                result = numerator + "";
            else
                result = numerator + "/" + denominator;
        }
        return result;
    }

    //---------------------------------------------------------------------------------------------
    // Reduces this rational number by dividing both the numerator and the denominator by their
    // greatest common divisor.
    //---------------------------------------------------------------------------------------------
    private void reduce ()
    {
        if (numerator != 0)
        {
            int common = gcd (Math.abs(numerator), denominator);

            numerator = numerator / common;
            denominator = denominator / common;
        }
    }

    //---------------------------------------------------------------------------------------------
    // Computes and returns the greatest common divisor of the two positive parameters. Uses
    // Euclid's algorithm.
    //---------------------------------------------------------------------------------------------
    private int gcd (int num1, int num2)
    {
        while (num1 != num2)
            if (num1 > num2)
                num1 = num1 - num2;
            else
                num2 = num2 - num1;

        return num1;
    }
}