//*************************************************************
// RationalNumber.java Author
//
// Represents one rational number with a number with a numerator and 
// denominator
//*************************************************************

public class RationalNumber
{
    private int numerator, denominator;
    //---------------------------------------------------------------
    // Constructor: Sets up the rational number by rnsuring a nonzero 
    // demonminator 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 = numer * -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. Assumes 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;
    }
}