using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;


namespace Calculator_Project
{
    public partial class Calculator : Form
    {
        public Calculator()
        {
            InitializeComponent();
        }


        //The Add Button
        private void Addbtn_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(TextboxOne.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 1 !");
                return;
            }

            if (string.IsNullOrEmpty(TextboxTwo.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 2!");
                return;
            }

            //int.Parse converts string to an integer form,
            double number1 = int.Parse(TextboxOne.Text );
            double number2 = int.Parse(TextboxTwo.Text);
            double answer;



            //This is will work out the answer in the 'Add Button' using the '+' operator.
            answer = number1 + number2;


            //The ResultBox.Text is the display in which the Answer is. The answer is worked out in the code containg the '+' operator.
            ResultBox.Text = answer.ToString();


        }

        //The Subtract Button
        private void Subbtn_Click(object sender, EventArgs e)
        {


            if (string.IsNullOrEmpty(TextboxOne.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 1!");
                return;
            }

            if (string.IsNullOrEmpty(TextboxTwo.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 2!");
                return;
            }

            double number1 = int.Parse(TextboxOne.Text);
            double number2 = int.Parse(TextboxTwo.Text);
            double answer;

            //This piece of code will work out the answer in the 'Sub Button' using the '-' operator.
            answer = number1 - number2;

            ResultBox.Text = answer.ToString();


        }

        //The Multiply Button
        private void Multbtn_Click(object sender, EventArgs e)
        {

            if (string.IsNullOrEmpty(TextboxOne.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 1!");
                return;
            }

            if (string.IsNullOrEmpty(TextboxTwo.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 2!");
                return;
            }

            double number1 = int.Parse(TextboxOne.Text);
            double number2 = int.Parse(TextboxTwo.Text);
            double answer;



            //This is will work out the answer in the 'Mult Button' using the '*' operator.
            answer = number1 * number2;

            ResultBox.Text = answer.ToString();


        }

        //The Divide Button

        private void Divbtn_Click(object sender, EventArgs e)
        {

            if (string.IsNullOrWhiteSpace(TextboxOne.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 1!");
                return;
            }

            if (string.IsNullOrWhiteSpace(TextboxTwo.Text))
            {
                MessageBox.Show("Please enter a value in Textbox 2!");
                return;
            }




            double number1 = int.Parse(TextboxOne.Text);
            double number2 = int.Parse(TextboxTwo.Text);
            double answer;


            if (TextboxOne.Text == "0" || TextboxTwo.Text == "0")
            {
                MessageBox.Show("This is a divison with 0 which cannot be carried out!");
                return;
            }

            if (number2 !=0)
            {
                //This is will work out the answer in the 'Div Button' using the '/' operator.
                answer = number1 / number2;
                ResultBox.Text = answer.ToString();
            }
            else
            {
                MessageBox.Show("This is a division by 0 which cannot be carried out!");
                return;
            }


        }

        //The clear Button
        private void Clearbtn_Click(object sender, EventArgs e)
        {
            //The operations sets the TextBox texts to 'nothing'.
            TextboxOne.Text = "";
            TextboxTwo.Text = "";
            ResultBox.Text = "";
        }

        private void TextboxOne_KeyPress(object sender, KeyPressEventArgs e)
        {
            //This piece of code prevents the user from typing letters int the text box at all.
            if (char.IsNumber(e.KeyChar))
            {


            }
            else
            {
                e.Handled = e.KeyChar != (char)Keys.Back;
            }
        }

        private void TextboxTwo_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (char.IsNumber(e.KeyChar))
            {


            }
            else
            {
                e.Handled = e.KeyChar != (char)Keys.Back;
            }
        }

        private void Calculator_Load(object sender, EventArgs e)
        {

        }

        private void TextboxOne_TextChanged(object sender, EventArgs e)
        {

        }
    }
}