PIbd-32.-Gerimovich-I.M.-COP/Library15Gerimovich/InputRealNumber.cs

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;
using Library15Gerimovich.Exceptions;

namespace Library15Gerimovich
{
    public partial class InputRealNumber : UserControl
    {
        private event EventHandler? _valueChanged;

        public InputRealNumber()
        {
            InitializeComponent();
        }

        public double? DoubleValue
        {
            get
            {
                if (IsNullCheckBox.Checked)
                {
                    return null;
                }

                if (string.IsNullOrEmpty(MainTextBox.Text))
                {
                    throw new EmptyValueException();
                }

                double ParsedDouble;
                if (double.TryParse(MainTextBox.Text, out ParsedDouble))
                {
                    return ParsedDouble;
                }
                else
                {
                    throw new MalformedRealException();
                }
            }
            set
            {
                SetNullState(value is null, true);
                if (value is not null)
                {
                    MainTextBox.Text = value.ToString();
                }
            }
        }

        public event EventHandler? ValueChanged
        {
            add { _valueChanged += value; }
            remove { _valueChanged -= value; }
        }

        private void SetNullState(bool IsNull, bool ClearText = false)
        {
            IsNullCheckBox.Checked = IsNull;
            MainTextBox.Enabled = !IsNull;

            if (ClearText)
            {
                MainTextBox.Text = string.Empty;
            }
        }

        private void IsNullCheckBox_CheckedChanged(object sender, EventArgs e)
        {
            SetNullState(IsNullCheckBox.Checked);
            _valueChanged?.Invoke(this, e);
        }

        private void MainTextBox_TextChanged(object sender, EventArgs e)
        {
            _valueChanged?.Invoke(this, e);
        }
    }
}