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 WinFormsLibrary1
{
    public class Error: Exception
    {
        string message;
        public Error(string text) { message = text; }
    }
    public partial class TextComponent : UserControl
    {
        public event EventHandler SelectedElementChange
        {
            add { checkBox1.CheckedChanged += value; textBox1.TextChanged += value; }
            remove { checkBox1.CheckedChanged -= value; textBox1.TextChanged -= value; }
        }
        public TextComponent()
        {
            InitializeComponent();
            
        }
        private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            if (checkBox1.Checked)
            {
                textBox1.ReadOnly = true;
                textBox1.Clear();
            }
            else textBox1.ReadOnly = false;
        }

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            char number = e.KeyChar;

            if (!Char.IsDigit(number))
            {
                e.Handled = true;
            }
        }

        public int? TextValue
        {
            get
            {
                if(!checkBox1.Checked)
                {
                    int result = -1;
                    int.TryParse(textBox1.Text, out result);
                    if( result == -1)
                    {
                        throw new Error("Несоответсвие");
                    }
                    return result;
                }
                return null;
            }
            set
            {
                checkBox1.Checked = value == null;
                textBox1.Text = value?.ToString();
            }
        }
    }
}