/* Includes */

// Objects
#include <iostream>
#include <string>

// Headers

#include <conio.h>
#include <time.h>
#include <stdlib.h>
#include <math.h>
#include <windows.h>

// Using

using namespace std;

/* Code */

class Calculator
{
private:
    char sign;
    double num1, num2, result;
    int functionID, temp;
    long seconds;

    void sleep()
    {
        clock_t start = clock();
        while (clock() - start < seconds);
    }

    void gotoXY(int x, int y)
    {
        COORD cur = {x, y};
        SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), cur);
    }

    void printHeader()
    {
        cout << "************************************" << endl;
        cout << "* Taschenrechner - Grundfunktionen *" << endl;
        cout << "************************************" << endl << endl;
    }

    void clearScreen()
    {
        system("cls");
    }

    void clearSTDIN()
    {
        fflush(stdin);
    }

    void getNumbers()
    {
        cout << "Bitte Zahl 1 eingeben: ";
        cin >> num1;
        cout << "Bitte Zahl 2 eingeben: ";
        cin >> num2;
        cout << endl;
        this->clearSTDIN();
    }

    void getFunctionID()
    {
        cout << "Bitte Funktion auswaehlen:" << endl << endl;
        cout << "1 - Addition" << endl;
        cout << "2 - Subtraktion" << endl;
        cout << "3 - Multiplikation" << endl;
        cout << "4 - Division" << endl << endl;
        cout << "Funktion: ";
        cin >> functionID;
    }

    bool getResult()
    {
        if ((functionID > 0) && (functionID < 5))
        {
            if (functionID == 1)
            {
                result = num1 + num2;
            }
            else if (functionID == 2)
            {
                result = num1 - num2;
            }
            else if (functionID == 3)
            {
                result = num1 * num2;
            }
            else if (functionID == 4)
            {
                result = num1 / num2;
            }
            return true;
        }
        return false;
    }

    void printResult()
    {
        cout << endl << "Ergebnis: " << result << endl << endl;
        cout << "Return zum Abbrechen, alle anderen Tasten zum Wiederholen.";
        sign = (char)_getch();
    }

    void cancel()
    {
        cout << endl << "Nur Funktionen (1 - 4) sind gueltig, Neustart in 5 Sekunden." << endl;
        for (temp = 4; temp >= 0; temp--)
        {
            this->sleep();
            this->gotoXY(49, 19);
            cout << temp;
            this->gotoXY(60, 19);
        }
        sign = '0';
    }

public:
    Calculator(int s)
    {
        seconds = s * 1000;
    }

    ~Calculator()
    {
    }

    void mainLoop()
    {
        do
        {
            this->clearScreen();
            this->clearSTDIN();
            this->printHeader();
            this->getNumbers();
            this->getFunctionID();
            if (this->getResult())
            {
                this->printResult();
            }
            this->cancel();
        }
        while (sign != 13);
    }
};

int main()
{
    Calculator calculator(1);
    calculator.mainLoop();
    return 0;
}