/// Returns bool for whether or not username & password combo are matched
int logIn()
{
    string un, pw, fn, ln, city, state;
    int choice = 0;
    int id;
    bool option = false;

	while (!option)
	{
		while (choice != 1 && choice != 2 && choice != 3)
		{
    			cout << "\t- WELCOME TO SPONGEBOOK -" << endl;
    			cout << "1. Log in " << endl;
    			cout << "2. Create an account " << endl;
    			cout << "3. Quit " << endl;
    			cout << "\nEnter choice: ";
    			cin >> choice;
    			cout << endl;
		}

		if (choice == 1)
		{
			int count = 0;

			while (true)
			{
				string userInput;

				cout << "\t- LOG IN -" << endl
    				 	 << "Username: ";
    				cin >> un;
    				cout << "Password: ";
    				cin >> pw;

    				for (int i = 1; i <= userID.size(); i++)
    				{
    					if (un == userID[i].getUsername() && pw == userID[i].getPassword())
    					{
    						cout << "\n\t*** Login successful ***\n" << endl;
    						id = i;
    						option = true;
    						return id;
    					}
    				}

    				cout << "\n\t*** Incorrect username or password. Please try again **" << endl;
    				count ++;

    				if (count > 3)
    				{
    					while (userInput != "YES" && userInput != "NO")
    					{
    						cout << "\nMultiple failed attempts. Would you like to go back to the main menu? ";
    						cin >> userInput;
    						transform(userInput.begin(), userInput.end(), userInput.begin(),::toupper);
    					}

    					if (userInput == "YES")
    					{
    						cout << endl;
    						choice = 0;
    						option = true;
    						return false;
    					}
    					else if (userInput == "NO")
    					{
    						choice = 1;
    						count = 0;
    					}

    				}

    			}
		}
		else if (choice == 2)
		{
   			cout << "\t- CREATE AN ACCOUNT -" << endl
			 	 << "First name: ";
			cin >> fn;

			cout << "Last name: ";
			cin >> ln;

		 	cout << "Username: ";
		 	cin >> un;

		 	cout << "Password: ";
		 	cin >> pw;

		 	cout << "City: ";
		 	cin.ignore();
		 	getline(cin, city);

		 	cout << "State: ";
		 	cin >> ws;
		 	cin >> state;

		 	id = userID.size() + 1;

		 	User newUser(fn, ln, un, pw, city, state, id);
		 	userID.push_back(newUser);

		 	cout << "\n\t*** Account successfully created. You may now log in ***\n" << endl;
		 	choice = 0;
		}
		else if (choice == 3)
		{
			cout << "\t- GOODBYE! -" << endl;
			exit(0);
		}
	}
    return id;
}