//file GroceryPurchasesOneTripFcns.cpp
//This program lets the user enter a filename.
//and reads in purchases info for a single trip to the store
//Program is broken into functions which illustrate the use of different numbers/type
//of parameters.

#include <iostream>
#include <string>
#include <cstring>   //needed to use c_str() member function
#include <fstream>
#include <iomanip>
using namespace std;

//function prototypes
bool openFile (ifstream &fin );
void readProcessInfo(ifstream &fin, double &purchaseTotal, int &countItem);
void printHeader();
void printTotals (double, int);

const double TAXRATE = 7.50;
int main()
{
    ifstream inputFile;          //the file variable
    double purchaseTotal = 0;    //total bill with tax
    int countItem = 0;           //how many different items purchased
    cout << setprecision(2) << fixed;
    openFile(inputFile);
    printHeader();
    readProcessInfo(inputFile, purchaseTotal,countItem);
    printTotals(purchaseTotal, countItem);
    inputFile.close();
    return 0;
}

 //function asks user for the external file name and opens it.
 //returns true if file opened, else returns false
  bool openFile (ifstream &fin)
   {
       string filename;
    // Get the filename from the user.
       cout << "Enter the filename: ";
       cin >> filename;
    // Open the file, using c_str() to convert the string object to a C-String as required
       fin.open(filename.c_str());
       if(fin)
       {
          return true;
       }
       else
       {
          cout << "File not found \n";
          return false;
       }
   }  //end openFile()
    void printHeader()
    {
        cout << setw(10) << right << "Amount" << "    " << right << "Count"  << '\t' << "Taxable?" << endl;
    }
//writes summary info to std output screen
    void printTotals(double purchaseTotal, int countItem)
    {
        cout << "Your total bill is "  << purchaseTotal << " for " << countItem <<  " Items" << endl;
    }

   //function reads purchase price, and number purchased and if it is taxable
   //It computes the total bill and count how many different types of items were purchased
   //and returns these values
   void readProcessInfo(ifstream &fin, double &purchaseTotal, int &countItem)
   {
        double purchase;    //cost of one item
        int howMany;        //number of that item purchased
        char taxable;       //X if taxable of - if not (in file)
        countItem = 0;
        purchaseTotal = 0;
        fin >> purchase >> howMany >> taxable;        //priming file input
        while (fin)   //read file till End of File
        {
            purchaseTotal = purchase*howMany + purchaseTotal;
            countItem++;
            if (taxable == 'X')
                purchaseTotal = (1 + TAXRATE/100)*purchaseTotal;
            else
                taxable = ' ';
            cout << setw(10) << right << purchase << '\t' << howMany << '\t' << "   " << taxable << endl;
            fin >> purchase >> howMany >> taxable;    //get next line of data
        }  //end while EOF loop
   }  //end readProcessInfo