/* Begin DO_NOT_MODIFY_REGION */

#include <stdio.h>
#include <stdlib.h>  /* Provides the abs function */
#include <string.h>

typedef struct fraction {
      int numerator;
      int denominator;
} Fraction;

int gcd(int x, int y);
/* Precondition: a and b must be positive */

Fraction ReduceFraction(Fraction R);

Fraction inputFraction();
/* Prompts for, inputs and returns a single fraction */


Fraction AddFractions(Fraction R1, Fraction R2);
/* Returns R1+R2 in reduced form */
Fraction SubtractFractions(Fraction R1, Fraction R2);
/* Returns R1-R2 in reduced form */
Fraction MultiplyFractions(Fraction R1, Fraction R2);
/* Returns R1*R2 in reduced form */
Fraction DivideFractions(Fraction R1, Fraction R2);
/* Precondition: in reduced form R2 must be nonzero
   Returns R1/R2 */

void PrintResult(Fraction R1, Fraction R2, int op);
/* Carries out the operation indicated by op and prints
   a string showing the two operand, the operator and the result */

void GetAndDoFractionOp(int op);
/* Prompts for two fractions
   then carries out the specified operation and prints
   the result.  In the case of division, checks to see
   if the second fraction is zero; if so, continues
   prompting for and inputing fractions until a nonzero
   fraction is input */

int main()
{
   char response, theOp;

   do {
      printf("\n\n-----------------------------------------");
      printf("\n\nEnter the operator you want to apply (+,-,*,/)\n");
      scanf(" %c",&theOp);
      while(getchar() != '\n');
      while( theOp != '+' && theOp != '-' && theOp != '*' && theOp != '/')
      {
     printf("%c is not a valid operator; try again\n",theOp);
     scanf(" %c",&theOp);
     while(getchar() != '\n');
      }
      GetAndDoFractionOp(theOp);
      printf("Do you wish to do another (Y/N)?");
      scanf(" %c",&response);
   } while(toupper(response) == 'Y');

   printf("Normal termination\n\n");
   return 0;
}

int gcd(int x, int y)
{
   if (x%y == 0)
      return y;
   return gcd(y,x%y);
}

Fraction ReduceFraction(Fraction R)
{
   int d;
   if (R.numerator == 0)
   {
      R.denominator = 1;
      return R;
   }
   d = gcd(abs(R.numerator),abs(R.denominator));
   R.numerator /= d;
   R.denominator /= d;

   if (R.denominator < 0)
   {
      R.numerator *= -1;
      R.denominator *= -1;
   }
   return R;
}

/* End DO_NOT_MODIFY_REGION */

/* You supply the definitions for the remaining functions */

Fraction InputFraction()
/* No prompts; just input the fraction */
{
   Fraction R = { 0, 0};
   scanf("%d/%d", &R.numerator, &R.denominator);
   while (R.denominator == 0){
    printf("The denominator cannot be 0, input again (n/d) \n");
    scanf("%d/%d", &R.numerator, &R.denominator);
   }
   return R;
}

Fraction AddFractions(Fraction R1, Fraction R2)
{
   Fraction R3 = {0, 0};

   R3.denominator = R1.denominator * R2.denominator;
   R3.numerator = R1.numerator * R2.denominator + R2.numerator * R1.denominator;
   R3 = ReduceFraction(R3);
   return R3;
}

Fraction SubtractFractions(Fraction R1, Fraction R2)
{
   Fraction R3 = {0, 0};

   R3.denominator = R1.denominator * R2.denominator;
   R3.numerator = R1.numerator * R2.denominator - R2.numerator * R1.denominator;
   R3 = ReduceFraction(R3);
   return R3;
}

Fraction MultiplyFractions(Fraction R1, Fraction R2)
{
   Fraction R3 = { 0, 0};

   R3.numerator = R1.numerator * R2.numerator;
   R3.denominator = R1.denominator * R2.denominator;
   R3 = ReduceFraction(R3);
   return R3;
}

Fraction DivideFractions(Fraction R1, Fraction R2)
{
   Fraction R3 = {0, 0};
   int temp = 0; /* place holder */

   temp = R2.numerator;

   R2.numerator = R2.denominator;
   R2.denominator = temp;

   R3.numerator = R1.numerator * R2.numerator;
   R3.denominator = R1.denominator * R2.denominator;
   R3 = ReduceFraction(R3);
   return R3;

}

void PrintResult(Fraction R1, Fraction R2, int op)
{
   Fraction R3 = {0, 0};

   if (op == '*'){
      R3 = MultiplyFractions (R1, R2);
      R3 = ReduceFraction(R3);
      printf ("%d/%d * %d/%d = %d/%d\n", R1.numerator, R1.denominator, R2.numerator, R2.denominator, R3.numerator, R3.denominator);
   }else if (op == '+'){
      R3 = AddFractions (R1, R2);
      R3 = ReduceFraction(R3);
      printf("%d/%d + %d/%d = %d/%d\n", R1.numerator, R1.denominator, R2.numerator, R2.denominator, R3.numerator, R3.denominator);
   }else if (op == '-'){
      R3 = SubtractFractions (R1, R2);
      R3 = ReduceFraction(R3);
      printf("%d/%d - %d/%d = %d/%d\n", R1.numerator, R1.denominator, R2.numerator, R2.denominator, R3.numerator, R3.denominator);
   }else {
      while (R2.numerator == 0 || R2.denominator == 0){
     printf ("Cannot divide by 0, input another fraction\n");
     R2 = InputFraction();
      }
      R3 = DivideFractions (R1, R2);
      R3 = ReduceFraction(R3);
      printf("%d/%d / %d/%d = %d/%d\n", R1.numerator, R1.denominator, R2.numerator, R2.denominator, R3.numerator, R3.denominator);
   }

}

void GetAndDoFractionOp(int op)
{
   Fraction R1 = {0, 0}, R2 = {0, 0};
   printf("Enter the first fraction argument (n/d): \n");
   R1 = InputFraction();
   printf("Enter the second fraction argument (n/d): \n");
   R2 = InputFraction();
   PrintResult (R1, R2, op);
}