// a Rational object holds one Rational number, one fraction
#include "rat.h"

//------------------------------ Rational ------------------------------------
// default constructor:  parameters are numerator and denominator respectively
// if the number is negative, the negative is always stored in the numerator
Rational::Rational(int n, int d) {
   numerator = d < 0 ? -n : n;
   denominator = d < 0 ? -d : d;
   reduce();
}

//--------------------------------- add --------------------------------------
// overloaded +: addition of 2 Rationals, current object and parameter
Rational Rational::add(const Rational& a) {
   Rational t;

   t.numerator = a.numerator * denominator + a.denominator * numerator;
   t.denominator = a.denominator * denominator;
   t.reduce();

   return t;
}

//------------------------------ subtract ------------------------------------
// subtraction of 2 Rationals, current object and parameter

Rational Rational::subtract(const Rational& s) {
   Rational t;

   t.numerator = s.denominator * numerator - denominator * s.numerator;
   t.denominator = s.denominator * denominator;
   t.reduce();

   return t;
}

//------------------------------ multiply ------------------------------------
// multiplication of 2 Rationals, current object and parameter
Rational Rational::multiply(const Rational& m) {
   Rational t;

   t.numerator = m.numerator * numerator;
   t.denominator = m.denominator * denominator;
   t.reduce();

   return t;
}

//-------------------------------- divide ------------------------------------
// division of 2 Rationals, current object and parameter,
// division by zero crashes
Rational Rational::divide(const Rational& v) {
   Rational t;

   t.numerator = v.denominator * numerator;
   t.denominator = denominator * v.numerator;
   t.reduce();

   return t;
}

//---------------------------- printRational ---------------------------------
void Rational::printRational() {
   if (denominator == 0)
      cout << endl << "DIVIDE BY ZERO ERROR!!!" << endl;
   else if (numerator == 0)
      cout << 0;
   else
      cout << numerator << "/" << denominator;
}

//------------------------ printRationalAsFloat ------------------------------
void Rational::printRationalAsFloat() {  
   if (denominator == 0)
      cout << endl << "DIVIDE BY ZERO ERROR!!!" << endl;
   else
      cout << float(numerator) / float(denominator);
}

//-------------------------------- reduce ------------------------------------
// reduce fraction to lowest terms
void Rational::reduce() {
   int n = numerator < 0 ? -numerator : numerator;
   int d = denominator;
   int largest = n > d ? n : d;

   int gcd = 0;                                 // greatest common divisor

   for (int loop = largest; loop >= 2; loop--)
      if (numerator % loop == 0 && denominator % loop == 0) {
         gcd = loop;
         break;
      }

   if (gcd != 0) {
      numerator /= gcd;
      denominator /= gcd;
   }
}