#include <iostream>
using namespace std; 
void menus(); // function prototype
int main() {
    int menu, choice;
    float metresSecond, kilometresHour, tempF, tempC;
	float usd, gbp, euro, oneGbpToEuro, oneGbpToUsd, valueOne, valueTwo, randomRate;
		cout << "For conversions involving speed press 1" << endl;
		cout << "For conversions involving temperature press 2" << endl;
		cout << "For conversions involving money press 3" << endl;
		cin >> menu;
    switch(menu) {
    case 1:
        system("cls");
		cout << "For ms^-1 to kmh^-1 press 1" << endl;
        cout << "For kmh^-1 to ms^-1 press 2" << endl;
        cin >> choice;   
        switch(choice) {
				case 1:
					cout << "Please enter your value in ms^-1" << endl;
					cin >> metresSecond;
					kilometresHour = ((metresSecond * 3600)/1000); 
					cout << "Your speed is: " << kilometresHour << "km/h" << endl;
					menus();
                break;
                case 2:
					cout << "Please enter your value in kmh^-1" << endl;
					cin >> kilometresHour;
					metresSecond = ((kilometresHour * 1000)/3600);
					cout << "Your speed is: " << metresSecond << "m/s" << endl;
					menus();
                break;
				default:
					cout<<"This isn't a valid option.";
					menus();
                break;
              }
		 break;
         
    case 2:
        system("cls");
		cout << "For Celcius to Fahrenheit press 1" << endl;
        cout << "For Fahrenheit to Celcius press 2" << endl;
        cin >> choice;
		switch (choice) {
				case 1:
					cout << "Please enter your value in Celcius" << endl;
					cin >> tempC;
					tempF = ((tempC * 9) /5) + 32;
					cout << "Your value is: " << tempF << "Degrees Fahrenheit" << endl;
					menus();
				break;
				case 2:
					cout << "Please enter your value in Fahrenheit" << endl;
					cin >> tempF;
					tempC = ((tempF - 32) * 5) / 9;
					cout << "Your value is; " << tempC << "Degrees Celcius" << endl;
					menus();
				break;
				default:
					cout<<"This isn't a valid option.";
					menus();
                break;
		 }
	case 3:
		system("cls");
		cout << "For GBP to USD press 1" << endl;
		cout << "For USD to GBP press 2" << endl;
		cout << "For GBP to Euro press 3" << endl;
		cout << "For Euro to GBP press 4" << endl;
		cout << "For OTHER conversion press 5" << endl;
		cin >> choice;
		switch (choice) {
				case 1:
					cout << "Please enter the conversion rate for 1 GBP to USD (eg 1.92)" << endl;
					cin >> oneGbpToUsd;
					cout << "Please enter your value in GBP" << endl;
					cin >> gbp;
					usd = (gbp * oneGbpToUsd);
					cout << "Your answer is " << usd << "Dollars" << endl;
					menus();
				break;
				case 2:
					cout << "Please enter the conversion rate for 1 GBP to USD (eg 1.92)" << endl;
					cin >> oneGbpToUsd;
					cout << "Please enter your value in USD" << endl;
					cin >> usd;
					gbp = (usd / oneGbpToUsd);
					cout << "Your answer is " << gbp << "Pounds" << endl;
					menus();
				break;
				case 3:
					cout << "Please enter the conversion rate for 1 GBP to Euros (eg 1.43)" << endl;
					cin >> oneGbpToEuro;
					cout << "Please enter your value in GBP" << endl;
					cin >> gbp;
					euro = (gbp * oneGbpToEuro);
					cout << "Your answer is " << euro << "Euros" << endl;
					menus();
				break;
				case 4:
					cout << "Please enter the conversion rate for 1 GBP to Euros (eg 1.43" << endl;
					cin >> oneGbpToEuro;
					cout << "Please enter your value in GBP" << endl;
					cin >> euro;
					gbp = (euro / oneGbpToEuro);
					cout << "Your answer is " << gbp << "Pounds" << endl;
					menus ();
				break;
				case 5:
					cout << "Please enter your conversion for Value 1 to Value 2 rate" << endl;
					cin >> randomRate;
					cout << "Please enter your first value" << endl;
					cin >> valueOne;
					valueTwo = (valueOne * randomRate);
					cout << "Your answer is" << valueTwo << endl;
					menus();
				break;
				default:
					cout<<"This isn't a valid option.";
					menus();
                break;
			}
		break;
    }
	return 0;
}
	void menus() {
		char exitChoice;
			cout << "\nPress Y to begin menu again, press N to exit\n";
			cin >> exitChoice;
		switch (exitChoice) {
		case 'y':
			system("cls"); 
			main(); 
		break;
		case 'n': 
			exit(0); 
		break;
		default:
			cout << "That isn't a correct option\n\n";
			menus();
		break;
	}
}