// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Windows.Forms;
using System.Windows.Forms.Design;
 
namespace System.ComponentModel.Design;
 
public partial class DateTimeEditor
{
    /// <summary>
    ///  UI we drop down to pick dates.
    /// </summary>
    private class DateTimeUI : Control
    {
        private readonly MonthCalendar _monthCalendar = new DateTimeMonthCalendar();
        private IWindowsFormsEditorService _editorService;
 
        public DateTimeUI(IWindowsFormsEditorService editorService, object? value)
        {
            InitializeComponent();
            Size = _monthCalendar.SingleMonthSize;
            _monthCalendar.Resize += MonthCalResize;
            _editorService = editorService;
            Value = value;
 
            if (value is not null)
            {
                DateTime dateTime = (DateTime)value;
                _monthCalendar.SetDate(dateTime.Equals(DateTime.MinValue) ? DateTime.Today : dateTime);
            }
        }
 
        public object? Value { get; private set; }
 
        protected override void Dispose(bool disposing)
        {
            _editorService = null!;
            Value = null;
 
            base.Dispose(disposing);
        }
 
        private void MonthCalKeyDown(object? sender, KeyEventArgs e)
        {
            switch (e.KeyCode)
            {
                case Keys.Enter:
                    OnDateSelected(sender, null);
                    break;
            }
        }
 
        protected override void RescaleConstantsForDpi(int deviceDpiOld, int deviceDpiNew)
        {
            base.RescaleConstantsForDpi(deviceDpiOld, deviceDpiNew);
 
            // Resizing the editor to fit to the SingleMonth size after Dpi changed.
            Size = _monthCalendar.SingleMonthSize;
        }
 
        private void InitializeComponent()
        {
            _monthCalendar.DateSelected += OnDateSelected;
            _monthCalendar.KeyDown += MonthCalKeyDown;
            Controls.Add(_monthCalendar);
        }
 
        private void MonthCalResize(object? sender, EventArgs e)
        {
            Size = _monthCalendar.Size;
        }
 
        private void OnDateSelected(object? sender, DateRangeEventArgs? e)
        {
            Value = _monthCalendar.SelectionStart;
            _editorService!.CloseDropDown();
        }
 
        protected override void OnGotFocus(EventArgs e)
        {
            base.OnGotFocus(e);
            _monthCalendar.Focus();
        }
 
        private class DateTimeMonthCalendar : MonthCalendar
        {
            protected override bool IsInputKey(Keys keyData) => keyData switch
            {
                Keys.Enter => true,
                _ => base.IsInputKey(keyData),
            };
        }
    }
}