// Simulate a grocery store checkout system with item info
// stored in a file and items purchased provided through
// standard input.
// Beth Katz, April 2006

#include <fstream>
#include <iostream>
#include <vector>;

using namespace std;

struct itemInfo {
   int number;
   string name;
   double price;
   string type;
};

// set up default output format and precision of digits after decimal
void setOutputFormat(int digits);

// obtain the database file name from the user and fill the
// item database with the information in the file
void fillItemDatabase(vector<itemInfo> & items);

// process an order of several items
void processOrder(const vector<itemInfo> & items);

// lookup a single item and return its index
// returns vector size if itemNumber is not found
unsigned int lookupItem(const vector<itemInfo> & items, int itemNumber);

// print information about one item purchase
void printItem(const itemInfo & item, double quantity, double cost);

int main( )
{
   vector<itemInfo> items;

   setOutputFormat(2);

   fillItemDatabase(items);
   processOrder(items);

   return 0;
}

// set up default output format and precision of digits after decimal
void setOutputFormat(int digits)
{
   cout.precision(digits);
   cout.setf(ios::fixed | ios::dec | ios::showpoint);
}

// obtain the database file name from the user and fill the
// item database with the information in the file
void fillItemDatabase(vector<itemInfo> & items)
{
   ifstream datafile;
   string filename;
   itemInfo i;

   cout << "Enter file name: ";
   cin >> filename;

   datafile.open(filename.c_str( ));
   if ( datafile.fail( ) ) {
      cout << "Cannot open data file: " << filename << endl;
      exit(1);
   }

   while (datafile >> i.number >> i.name >> i.price >> i.type) {
      items.push_back(i);
   }

   datafile.close();
}

// process an order of several items
void processOrder(const vector<itemInfo> & items)
{
   double total = 0.0;
   int itemNumber;
   double quantity;
   unsigned int index;
   double cost;

   while (cin >> itemNumber >> quantity) {
      index = lookupItem(items, itemNumber);
      if (index == items.size( )) {
         cout << "Item " << itemNumber << " unknown. Skipping." << endl;
      } else if (quantity <= 0) {
         cout << quantity << " is not positive. Skipping." << endl;
      } else {
         cost = items[index].price * quantity;
         total += cost;
         printItem(items[index], quantity, cost);
      }
   }
   cout << endl << "Total = $" << total << endl;

}

// lookup a single item and return its index
// returns items vector size if itemNumber is not found
unsigned int lookupItem(const vector<itemInfo> & items, int itemNumber)
{
   unsigned int i;
   for (i = 0; (i < items.size( )) && (items[i].number != itemNumber); i++) {
   }
   return i;
}

// print information about one item purchase
void printItem(const itemInfo & item, double quantity, double cost)
{
   cout << item.name << " ";
   if (item.type == "pounds") {
      cout << quantity << " lb" << " @ " << item.price << "/lb";
   } else {
      cout << int(quantity) << " @ " << item.price << " each";
   }
   cout << " = $" << cost << endl;
}