// Karl Ramberg
// 2-17-19
// CS181 - Assignment 1 - Q4

#include<iostream>
#include<fstream>

using namespace std;

struct Division
{
    string name;
    int id;
    double sales;
    int year;
};

void openFile(string &filename, fstream &file);

void readFile(string filename, fstream &file);

void writeFile(string filename, fstream &file);

void modifyFile(string filename, fstream &file);

void getInfo(Division &div);

int main()
{
    fstream file;
    string filename;
    openFile(filename, file);

    int choice;
    cout << "(1) Read, (2) Write, (3) Modify, or (4) Quit? ";
    cin >> choice;

    while(choice != 1 && choice != 2 && choice != 3 && choice != 4)
    {
	cout << "Not a valid operation" << endl;
	cout << "(1) Read, (2) Write, (3) Modify, or (4) Quit? ";
	cin >> choice;
    }
    while(choice != 4)
    {
	if(choice == 1)
	{
	    readFile(filename, file);
        }
	else if(choice == 2)
        {
	    writeFile(filename, file);
        }
	else
        {
	   modifyFile(filename, file);
        }

	cout << "(1) Read, (2) Write, (3) Modify, or (4) Quit? ";
	cin >> choice;
	while(choice != 1 && choice != 2 && choice != 3 && choice != 4)
	{
	    cout << "Not a valid operation" << endl;
	    cout << "(1) Read, (2) Write, (3) Modify, or (4) Quit? ";
	    cin >> choice;
	}
    }

    file.close();
}

void openFile(string &filename, fstream &file)
{
    cout << "Choose a file: ";
    cin >> filename;

    file.open(filename, ios::in | ios::out | ios::binary);
    while(file.fail())
    {
	cout << "Cannot read that file" << endl;
	cout << "Choose a file: ";
	cin >> filename;
	file.open(filename, ios::in | ios::out | ios::binary);
    }
}

void readFile(string filename, fstream &file)
{
    cout << "Reading " << filename << "..." << endl;

    file.seekg(0);
    file.clear();
    Division div;
    while(!file.eof())
    {
	file.read(reinterpret_cast<char *>(&div), sizeof(div));

	cout << endl;
	cout << "Name:  " << div.name << endl;
	cout << "ID:    " << div.id << endl;
	cout << "Sales: $" << div.sales << endl;
	cout << "Year:  " << div.year << endl;
	cout << endl;
    }
}

void writeFile(string filename, fstream &file)
{
    cout << "Writing to " << filename << "..." << endl;

    Division div;
    getInfo(div);

    file.seekp(ios::end);
    file.write(reinterpret_cast<char *>(&div), sizeof(div));

    cout << endl;
}

void modifyFile(string filename, fstream &file)
{
    int divNum;
    cout << "Which record would you like to modify? ";
    cin >> divNum;

    Division div;
    getInfo(div);

    file.seekp(divNum * sizeof div);
    file.write(reinterpret_cast<char *>(&div), sizeof div);
}

void getInfo(Division &div)
{
    string dummy;
    getline(cin, dummy);

    string name;
    cout << "Enter a name: ";
    getline(cin, name);
    while(name == "")
    {
	cout << "Invalid name" << endl;
	cout << "Enter a name: ";
	getline(cin, name);
    }

    int id;
    cout << "Enter an ID: ";
    cin >> id;
    while(id < 0)
    {
	cout << "ID cannot be negative" << endl;
	cout << "Enter an ID: ";
	cin >> id;
    }

    double sales;
    cout << "Enter total sales: ";
    cin >> sales;
    while(sales < 0.0)
    {
	cout << "Sales cannot be negative" << endl;
	cout << "Enter total sales: ";
	cin >> sales;
    }

    int year;
    cout << "Enter a year: ";
    cin >> year;
    while(year < 0)
    {
	cout << "Year cannot be negative" << endl;
	cout << "Enter a year: ";
	cin >> year;
    }

    div.name = name;
    div.id = id;
    div.sales = sales;
    div.year = year;
    cout << div.name << " " << div.id << " " << div.sales << " " << div.year << endl;
}