#include <iostream>
#include <fstream>

using namespace std;

const int SIZE = 51;                                                    //array size
const int NUM_REC = 10;

struct Inventory                                                        //declare structure to hold related variables
{
    char itemDescription[SIZE];
    int quantityOnHand;
    double wholesaleCost;
    double retailPrice;
    int dateAdded;
};

int main()
{
    Inventory record = { " ", 0, 0.0, 0.0, 000000 };                        //create empty structure
    char again;
    
    fstream store("store.dat", ios::out | ios::binary);                     //open file for binary output
    
    for(int count = 0; count < NUM_REC; count++)
        store.write(reinterpret_cast<char *>(&record), sizeof(record));     //write blank record
    
    store.close();
    
    store.open("store.dat", ios::in | ios::binary);                         //open file for binary input
    if(!store)                                                              //test for file error
    {
        cout << "Error opening file. Program aborting.\n";
        return 0;
    }
    
    cout << endl;
    //cout << "Here are the records in the file: \n";
    store.read(reinterpret_cast<char *>(&record), sizeof(record));          //read and display records
    
    while (!store.eof())
    {
        cout << endl;
        cout << "Item Description: ";
        cout << record.itemDescription << endl;
        cout << "Quantity on hand: ";
        cout << record.quantityOnHand << endl;
        cout << "Current wholesale cost: $";
        cout << record.wholesaleCost << endl;
        cout << "Current retail price: $";
        cout << record.retailPrice << endl;
        cout << "Dated added to inventory (yymmdd): ";
        cout << record.dateAdded << endl;
        store.read(reinterpret_cast<char *>(&record), sizeof(record));
    }
    cout << "That's all the data in the file.\n";
    store.close();                                                          //close the file
    
    long recNum;
    
    store.open("store.dat", ios::in | ios::out | ios::binary);              //open file for binary output/input/edits
    if(!store)                                                              //test for file error
    {
        cout << "Error opening file. Program aborting.\n";
        return 0;
    }
    
    cout << endl;
    cout << "Would you like to edit a record: ";
    cin >> again;
    if(again == 'y' || again == 'Y')
    {
        do
        {
            cout << "Which record do you want to edit: ";
            cin >> recNum;
            
            store.seekg(recNum * sizeof(record), ios::beg);                 //set read location to start of record
            store.read(reinterpret_cast<char *>(&record), sizeof(record));  //read record to edit
            
            cout << endl;
            cout << "Item Description: ";
            cout << record.itemDescription << endl;
            cout << "Quantity on hand: ";
            cout << record.quantityOnHand << endl;
            cout << "Current wholesale cost: $";
            cout << record.wholesaleCost << endl;
            cout << "Current retail price: $";
            cout << record.retailPrice << endl;
            cout << "Dated added to inventory (yymmdd): ";
            cout << record.dateAdded << endl;
            
            cout << endl;
            cout << "Please enter the new data.\n";
            cout << "Item Description: ";                                   //get user input
            cin.ignore();
            cin.getline(record.itemDescription, SIZE);
            cout << "Quantity on hand: ";
            cin >> record.quantityOnHand;
            while(record.quantityOnHand < 0)
            {
                cout << "Please enter quantity amount equal \n";
                cout << "to or greater than 0: ";
                cin >> record.quantityOnHand;
            };
            cout << "Current wholesale cost: ";
            cin >> record.wholesaleCost;
            while(record.wholesaleCost < 0)
            {
                cout << "Please enter Wholesale Cost equal \n";
                cout << "to or greater than 0: ";
                cin >> record.wholesaleCost;
            };
            cout << "Current retail price: ";
            cin >> record.retailPrice;
            while(record.retailPrice < record.wholesaleCost)
            {
                cout << "Please enter Retail Price equal to or \n";
                cout << "greater than Wholesale Cost: ";
                cin >> record.retailPrice;
            };
            cin.ignore();
            cout << "Dated added to inventory (yymmdd): ";
            cin >> record.dateAdded;
            while(record.dateAdded < 160101)
            {
                cout << "Date added must be later than Jan 1, 2016.\n";
                cout << "Please re-enter date added to inventory (yymmdd): ";
                cin >> record.dateAdded;
            };
            store.seekp(recNum * sizeof(record), ios::beg);                 //go back to beginning of record to edit
            store.write(reinterpret_cast<char *>(&record), sizeof(record)); //overwrite with new data
            cout << "Do you want to edit another record.\n";
            cin >> again;
            cin.ignore();
        }while(again == 'y' || again == 'Y');
    }
   
    store.close();                                                          //close file
    
    store.open("store.dat", ios::in | ios::binary);                         //open file for binary input
    if(!store)                                                              //test for error
    {
        cout << "Error opening file. Program aborting.\n";
        return 0;
    }
    
    cout << "Here are the updated records in the file: \n";
    store.read(reinterpret_cast<char *>(&record), sizeof(record));          //read file for updated records
    
    while (!store.eof())
    {
        cout << endl;
        cout << "Item Description: ";
        cout << record.itemDescription << endl;
        cout << "Quantity on hand: ";
        cout << record.quantityOnHand << endl;
        cout << "Current wholesale cost: $";
        cout << record.wholesaleCost << endl;
        cout << "Current retail price: $";
        cout << record.retailPrice << endl;
        cout << "Dated added to inventory (yymmdd): ";
        cout << record.dateAdded << endl;
        
        cout << "\nPress the Enter key to see the next record.\n";
        cin.get(again);
        
        store.read(reinterpret_cast<char *>(&record), sizeof(record));
    }
    cout << "That's all the data in the file.\n";
    store.close();
    
    return 0;
}