// the purpose of this program is to calculate the future value you would get based on  a certain present value
#include <iostream>
#include <fstream>									//header files, fstream to use files, cmath to use the pow function, and iomanip for output formatting
#include <cmath>
#include <iomanip>

using namespace std;

int readFile(ifstream& infile, double& presentValue, double& interestRate, int& months);
double calculateFutureValue(double presentValue, double& interestRate, int months);								//function prototyping so main can be the first
void writeFile(ofstream& outfile, double presentValue, double interestRate, int months, double futureValue);	// function

int main()
{


   string fileName;
   cin >> fileName;
   	   	   	   	   	   	   	   	   	   	   	   	   	   	   // get input from a file typed by the user
   ifstream infile;
   infile.open(fileName);

   if (infile) 																				// if the file was correctly opened perform the following actions
   {

      double presentVal;
      double intRate;
      int months;												//variables to store values in and then use in the output file
      int read;
      double futureVal;

      ofstream outfile;
      outfile.open("output.xls");											// create and open a file called output.xls, .xls is excel sheet

      if (outfile)																			//if the outfile opened correctly perform the following actions
      {

         outfile << "Future Value\tPresent Value\tMonthly Interest\tMonths" << endl;			// always output this statement at the beginning of the file
         while (infile >> presentVal)
         {
            read = readFile(infile, presentVal, intRate, months); 							//calling the read function
            if (read == 1) 																	// if read is true perform the other functions
            {
               futureVal = calculateFutureValue(presentVal, intRate, months);
               writeFile(outfile, presentVal, intRate, months, futureVal);
            }
            else
            {
               intRate = intRate * 100;

               cout << setprecision(2) << fixed;													//else tell the user that one of the values was invalid
               cout << presentVal << " " << intRate << " ";
               cout << setprecision(0) << fixed << months << endl;
               cout << "One or more of the above values are not greater than zero" << endl;
            }

         }
      }
      else
      {
         cout << "File \"output.xls\" could not be opened" << endl;
         infile.close();															// if the file could not be opened correctly tell the user and close the file
         return 0;
      }

      infile.close();
   }
   else
   {
      cout << "File \"" << fileName << "\" could not be opened" << endl;
   }

   return 0;
}



int readFile(ifstream& infile, double& presentValue, double& interestRate, int& months) //read in function for files
{
   unsigned int end;


   infile >> interestRate;
   interestRate = interestRate / 100; 											//read in the values and convert interest rate to percentage
   infile >> months;

   if (presentValue > 0 && interestRate > 0 && months > 0)
   {
      end = 1;																	// this will indicate if the values were read properly
   }
   else if (presentValue <= 0 || interestRate <= 0 || months <= 0)
   {
      end = 2;																	// this will indicate if there was an invalid value
   }
   else
   {
      end = 0;																	// this will indicate that the program reached the end of the file
   }

   return end;												// return one of those values
}

double calculateFutureValue(double presentValue, double& interestRate, int months) 	// calculation function
{
   double futureValue;

   futureValue = presentValue * pow((1 + interestRate), months); 			//calculation for future value
   interestRate = interestRate * 100; 										// after calculations, return interest rate to its original value

   return futureValue;
}

void writeFile(ofstream& outfile, double presentValue, double interestRate, int months, double futureValue) //output function for files
{


   outfile << setprecision(2) << fixed;																			//setting the values to decimal value
   outfile << futureValue << "\t" << presentValue << "\t" << interestRate << "\t";
   outfile << setprecision(0) << fixed << months << endl;															//outputting the values to a file
}