namespace Calculator
{
    public partial class Form1 : Form
    {
        string text = "0";
        double firstNumber;
        string operation;
        public Form1()
        {
            InitializeComponent();
        }

        private void numButtonClick(object sender, EventArgs e)
        {
            Button button = (Button)sender;
            if(textBox1.Text == "0" && textBox1.Text != null)
            {
                textBox1.Text = button.Text;
                text = button.Text;
            }
            else
            {
                textBox1.Text += button.Text;
                text = button.Text;
            }
        }

        private void button11_Click(object sender, EventArgs e)
        {
            firstNumber = Convert.ToDouble(text);
            textBox1.Text += "+";
            text = "0";
            operation = "+";
        }

        private void button12_Click(object sender, EventArgs e)
        {
            firstNumber = Convert.ToDouble(text);
            textBox1.Text += "-";
            text = "0";
            operation = "-";
        }

        private void button13_Click(object sender, EventArgs e)
        {
            firstNumber = Convert.ToDouble(text);
            textBox1.Text += "x";
            text = "0";
            operation = "x";
        }

        private void button14_Click(object sender, EventArgs e)
        {
            firstNumber = Convert.ToDouble(text);
            textBox1.Text += "/";
            text = "0";
            operation = "/";
        }

        private void button15_Click(object sender, EventArgs e)
        {
            textBox1.Text = "0";
            text = "0";
            firstNumber = 0;
        }

        private void button16_Click(object sender, EventArgs e)
        {
            textBox1.Text += ",";
        }

        private void button18_Click(object sender, EventArgs e)
        {
            textBox1.Text = textBox1.Text.Remove(textBox1.Text.Length - 1);
            text = text.Remove(text.Length - 1);
        }

        private void button17_Click(object sender, EventArgs e)
        {
            double secondNumber = Convert.ToDouble(text);
            double result = 0;
            if (operation == "+")
            {
                result = firstNumber + secondNumber;
            }
            else if (operation == "-")
            {
                result = firstNumber - secondNumber;
            }
            else if (operation == "x")
            {
                result = firstNumber * secondNumber;
            }
            else if (operation == "/")
            {
                if (secondNumber == 0)
                {
                    textBox1.Text = "Cannot divide by zero";
                }
                else
                {
                    result = firstNumber / secondNumber;
                }
            }

            textBox1.Text = Convert.ToString(result);
            text = Convert.ToString(result);
            firstNumber = result;

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }
    }
}