using System;
using System.Linq;

namespace WykopowyKalkulator1
{
    internal static class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Write 'exit' to exit xD");
            Console.WriteLine("Value1 operation Value2 i.e.");
            Console.WriteLine("50 / 50");

            while (true)
            {
                Console.WriteLine("Enter calculation:");
                var read = Console.ReadLine();
                if (read != null && read.Equals("exit", StringComparison.OrdinalIgnoreCase))
                {
                    Console.WriteLine("Elo");
                    break;
                }

                var values = read?.Split(' ').Select(e => e.Trim()).ToArray();

                if (values == null) continue;

                var calculator = new CalculatorEngine<double>(
                    values[1],
                    Double.Parse(values[0]),
                    Double.Parse(values[2]));

                Console.WriteLine(calculator.Calculate());
            }
        }
    }

    public class CalculatorEngine<T>
    {
        private readonly Operations _operation;
        private readonly T _x;
        private readonly T _y;

        private enum Operations
        {
            Add,
            Subtract,
            Multiply,
            Divide
        }


        private CalculatorEngine(Operations operation, T x, T y)
        {
            _operation = operation;
            _x = x;
            _y = y;
        }


        public CalculatorEngine(string operation, T x, T y) : this(ConvertOperation(operation), x, y)
        {
        }

        public T Calculate()
        {
            return (T) CalculateDynamic();
        }

        private dynamic CalculateDynamic()
        {
            dynamic x = _x;
            dynamic y = _y;

            switch (_operation)
            {
                case Operations.Add:
                    return x + y;
                case Operations.Subtract:
                    return x - y;
                case Operations.Multiply:
                    return x * y;
                case Operations.Divide:
                    return x / y;
                default:
                    throw new ArgumentOutOfRangeException(nameof(_operation), _operation, null);
            }
        }

        private static Operations ConvertOperation(string userInput)
        {
            if (userInput.Equals("add", StringComparison.OrdinalIgnoreCase)
                || userInput.Equals("+", StringComparison.OrdinalIgnoreCase))
                return Operations.Add;

            if (userInput.Equals("subtract", StringComparison.OrdinalIgnoreCase)
                || userInput.Equals("-", StringComparison.OrdinalIgnoreCase))
                return Operations.Subtract;

            if (userInput.Equals("multiply", StringComparison.OrdinalIgnoreCase)
                || userInput.Equals("*", StringComparison.OrdinalIgnoreCase)
                || userInput.Equals("x", StringComparison.OrdinalIgnoreCase))
                return Operations.Multiply;

            if (userInput.Equals("divide", StringComparison.OrdinalIgnoreCase)
                || userInput.Equals("/", StringComparison.OrdinalIgnoreCase))
                return Operations.Divide;

            throw new Exception("Co do ch**");
        }
    }
}