package rational;

public class RationalNumber implements Comparable {
   private int numerator;
   private int denominator;

   public RationalNumber(int numer, int denom) {
      numerator = numer;
      denominator = denom;
      if (denominator == 0) // handle 0 denominator
         denominator = 1;
      if (denominator < 0) { // Make the numerator "store" the sign
         numerator = numerator * -1;
         denominator = denominator * -1;
      }
      reduce();
   }

   public int compareTo(Object obj) {
      RationalNumber otherObj = (RationalNumber)obj;
      double result = getDecimalEquivalent() -
                      otherObj.getDecimalEquivalent();
      if (result > 0)
         return 1;
      else if (result < 0)
         return -1;
      return 0;
   }

   public double getDecimalEquivalent( ) {
      return (double)numerator/denominator;
   }

   public int getNumerator() {
      return numerator;
   }


   public int getDenominator() {
      return denominator;
   }

   public RationalNumber reciprocal() {
       return new RationalNumber(denominator, numerator);
   }

   public RationalNumber add(RationalNumber op2) {
       int newDenom = denominator * op2.getDenominator();
       int newNumer = numerator*op2.getDenominator() +
                      op2.getNumerator()*denominator;
       return new RationalNumber(newNumer, newDenom);
   }

   public RationalNumber subtract(RationalNumber op2) {
       int newDenom = denominator * op2.getDenominator();
       int newNumer = numerator * op2.getDenominator() -
             op2.getNumerator() * denominator;
       return new RationalNumber(newNumer, newDenom);
    }

   public RationalNumber multiply(RationalNumber op2) {
       int newDenom = denominator*op2.getDenominator();
       int newNumer = numerator*op2.getNumerator();
       return new RationalNumber(newNumer, newDenom);
   }

   public RationalNumber divide(RationalNumber op2) {
       int newDenom = denominator * op2.getNumerator();
       int newNumer = numerator * op2.getDenominator();
       return new RationalNumber(newNumer, newDenom);
    }

   public boolean equals(RationalNumber op2) {
      if (numerator == op2.getNumerator() &&
          denominator == op2.getDenominator())
         return true;
       return false;
   }

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

   
   // This assumes that the numerator is not negative
   private void reduce() { // divide numerator and denominator by gcd to reduce
      if (numerator != 0) {
         int common = gcd(Math.abs(numerator), denominator);
         numerator = numerator / common;
         denominator = denominator / common;
      }
      else
          denominator = 1;  // so 0 is unique
   }

   private int gcd(int num1, int num2) { // a slow, non-traditional method
      while (num1 != num2)
         if (num1 > num2)
            num1 = num1 - num2;
         else
            num2 = num2 - num1;
      return num1;
   }
}