//************************************************************************
// Program to do fraction arithmetic 
//
// Written by : Rex Forsyth
//************************************************************************

#include <iostream>
#include <cctype>
#include "fraction.h"
#include "myio.h"

using namespace std;

// function prototypes
void instruct();
void getQuestion(fraction& frac1, fraction& frac2, char& oper);
void getOperator(char& oper);
fraction doCalculation(const fraction& frac1,const fraction& frac2,char oper);
void displayResult(const fraction& frac1,const fraction& frac2,char oper,
		   const fraction& result);
void getValid(fraction& frac);


//************************************************************************
//************************************************************************
int main()
{

   fraction first;               // first fraction
   fraction second;              // second fraction
   char oper;
   fraction result;              // the result
   
   instruct();
   do {
      getQuestion(first, second, oper);
      if (oper == '/' && second.num() == 0)
	 cout << "Division by zero is not allowed!!!" << endl;
      else {
	 result = doCalculation(first, second, oper);
	 displayResult(first, second, oper, result);
      }
      clrStream();   // clear the new line if nothing else
                     // to prepare for character input
      cout << "Do you want to continue (n to stop)? ";
   } while (tolower(getResponse('y')) != 'n');

   cout << "Just testing the comparison and printMixed methods" << endl;

   first.printMixed(cout); 
   if (first.sameAs(second)) cout << " = "; else cout << " != ";
   second.printMixed(cout); cout << endl;
   
   first.printMixed(cout);
   if (first.isLessThan(result)) cout << " < "; else cout << " >= ";
   result.printMixed(cout); cout << endl;

   return 0;
}







//************************************************************************
// function to explain how to use this program
//************************************************************************
void instruct() {

   cout << "This program will ask for a fraction expression involving" << endl;
   cout << "two fractions and an operator (+,-,* or /).  It will then" << endl;
   cout << "calculate and print the result.  The fraction should be" << endl;
   cout << "entered in the form a/b where a and b are integers. If " << endl;
   cout << "denominator is 1, the fraction can be entered without" << endl;
   cout << "the / and the denominator. All fractions will be reduced" << endl;
   cout << "to lowest terms with the denominator positive.  Examples " << endl;
   cout << "of valid input are : " << endl;
   cout << "     3/4" << endl;
   cout << "     3" << endl;
   cout << "     10/12" << endl;
   cout << "     -3/4" << endl;
   cout << "     3/-4" << endl;
   cout << "     0" << endl;
   cout << endl << endl;
}


//************************************************************************
// function to get the question 
//
// parameter usage
//     frac1 -- exports the first fraction
//     frac2 -- exports the second fraction
//     oper -- exports the operator to apply
//
// Post-Conditions : fractions will be valid and reduced to lowest terms
//                       with the denominator positive.
//                   the operator will be one of + - * /
//************************************************************************
void getQuestion(fraction& frac1, fraction& frac2, char& oper) {
   
   cout << "Enter first fraction -- ";
   getValid(frac1);

   cout << "Enter the operator (one or + - * /)  -- ";
   getOperator(oper);
   
   cout << "Enter second fraction -- ";
   getValid(frac2);
}


//***********************************************
// function to get a valid fraction from the user
// 
//***********************************************
void getValid(fraction& frac) {

   while (true) {
      frac.read(cin);
      if (cin.good()) break;

      cout << " Not a valid fraction!! Try again -- ";
      cin.clear();
      clrStream();  
   }
}



//************************************************************************
// function to get an operator
//
// parameter usage
//     oper -- exports the operator
//
// Post-Conditions : the operator will be one of + - * /
//************************************************************************
void getOperator(char& oper) {

   cin >> oper;
   while (oper != '+' && oper != '-' && oper != '*' && oper != '/') {
      cout << "Invalid operator entered!! Must be one of +,-,*,/. Reenter -- ";
      cin >> oper;
   }
}

//************************************************************************
// function to apply the operator to the two fraction to get the result
//
// parameter usage
//     frac1 -- imports the first fraction
//     frac2 -- imports the second fraction
//      oper -- imports the operator to apply
//
//  Pre-Conditions : the two fractions will be valid and reduced to lowest 
//                       terms with the denominator positive.
//                   if the oper is '/' then num2 is not 0
//                   the operator will be one of + - * /
// Post-Conditions : the returned result will be reduced to lowest terms
//                       with the denominator positive.
//************************************************************************
fraction doCalculation(const fraction& frac1,const fraction& frac2,char oper) {

   switch (oper) {
      case '+' : return frac1.add(frac2); break;
      case '-' : return frac1.sub(frac2); break;
      case '*' : return frac1.mult(frac2); break;
      case '/' : return frac1.div(frac2); break;
   }
}

//************************************************************************
// function to display the expression and the result
//
// parameter usage
//     frac1 -- imports the first fraction
//     frac2 -- imports the second fraction
//      oper -- imports the operator to apply
//    result -- imports the result fraction
//
//  Pre-Conditions : all fractions will be valid and reduced to lowest 
//                       terms with the denominator positive.
//                   the operator will be one of + - * /
//************************************************************************
void displayResult(const fraction& frac1,const fraction& frac2,char oper,
		   const fraction& result) {
   frac1.print(cout);
   cout << ' ' <<  oper << ' ';
   frac2.print(cout);
   cout << " = ";
   result.print(cout);
   cout << endl << endl;
}