feat: implement single date selector.

src/Ursa/Controls/DateTimePicker/DatePicker.cs

@@ -1,8 +1,162 @@
-using Avalonia.Controls.Primitives;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Irihi.Avalonia.Shared.Contracts;
+using Irihi.Avalonia.Shared.Helpers;
 
 namespace Ursa.Controls;
 
-public class DatePicker: DatePickerBase
+[TemplatePart(PART_Button, typeof(Button))]
+[TemplatePart(PART_Popup, typeof(Popup))]
+[TemplatePart(PART_TextBox, typeof(TextBox))]
+[TemplatePart(PART_Calendar, typeof(CalendarView))]
+public class DatePicker: DatePickerBase, IClearControl
 {
+    public const string PART_Button = "PART_Button";
+    public const string PART_Popup = "PART_Popup";
+    public const string PART_TextBox = "PART_TextBox";
+    public const string PART_Calendar = "PART_Calendar";
+    private Button? _button;
+    private Popup? _popup;
+    private TextBox? _textBox;
+    private CalendarView? _calendar;
+
+    public static readonly StyledProperty<DateTime?> SelectedDateProperty = AvaloniaProperty.Register<DatePicker, DateTime?>(
+        nameof(SelectedDate));
+
+    public DateTime? SelectedDate
+    {
+        get => GetValue(SelectedDateProperty);
+        set => SetValue(SelectedDateProperty, value);
+    }
+
+    static DatePicker()
+    {
+        SelectedDateProperty.Changed.AddClassHandler<DatePicker, DateTime?>((picker, args) =>
+            picker.OnSelectionChanged(args));
+    }
+
+    private void OnSelectionChanged(AvaloniaPropertyChangedEventArgs<DateTime?> args)
+    {
+        if (args.NewValue.Value is null)
+        {
+            _calendar?.ClearSelection();
+            _textBox?.Clear();
+        }
+        else
+        {
+            _calendar?.MarkDates(startDate: args.NewValue.Value, endDate: args.NewValue.Value);
+            _textBox?.SetValue(TextBox.TextProperty, args.NewValue.Value.Value.ToString(DisplayFormat ?? "yyyy-MM-dd"));
+        }
+    }
+
+    protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+    {
+        base.OnApplyTemplate(e);
+
+        GotFocusEvent.RemoveHandler(OnTextBoxGetFocus, _textBox);
+        TextBox.TextChangedEvent.RemoveHandler(OnTextChanged, _textBox);
+        PointerPressedEvent.RemoveHandler(OnTextBoxPointerPressed, _textBox);
+        Button.ClickEvent.RemoveHandler(OnButtonClick, _button);
+        if (_calendar != null)
+        {
+            _calendar.OnDateSelected -= OnDateSelected;
+        }
+        
+        _button = e.NameScope.Find<Button>(PART_Button);
+        _popup = e.NameScope.Find<Popup>(PART_Popup);
+        _textBox = e.NameScope.Find<TextBox>(PART_TextBox);
+        _calendar = e.NameScope.Find<CalendarView>(PART_Calendar);
+        
+        Button.ClickEvent.AddHandler(OnButtonClick, RoutingStrategies.Tunnel, true, _button);
+        GotFocusEvent.AddHandler(OnTextBoxGetFocus, _textBox);
+        TextBox.TextChangedEvent.AddHandler(OnTextChanged, _textBox);
+        PointerPressedEvent.AddHandler(OnTextBoxPointerPressed, RoutingStrategies.Tunnel, false, _textBox);
+        
+        if (_calendar != null)
+        {
+            _calendar.OnDateSelected += OnDateSelected;
+        }
+    }
+
+    private void OnDateSelected(object sender, CalendarDayButtonEventArgs e)
+    {
+        SetCurrentValue(SelectedDateProperty, e.Date);
+    }
+
+    private void OnButtonClick(object sender, RoutedEventArgs e)
+    {
+        Focus(NavigationMethod.Pointer);
+        SetCurrentValue(IsDropdownOpenProperty, !IsDropdownOpen);
+    }
+
+    private void OnTextBoxPointerPressed(object sender, PointerPressedEventArgs e)
+    {
+        SetCurrentValue(IsDropdownOpenProperty, true);
+    }
+
+    private void OnTextChanged(object sender, TextChangedEventArgs e)
+    {
+        if (string.IsNullOrEmpty(_textBox?.Text))
+        {
+            SetCurrentValue(SelectedDateProperty, null);
+            _calendar?.ClearSelection();
+        }
+        else if (DisplayFormat is null || DisplayFormat.Length == 0)
+        {
+            if (DateTime.TryParse(_textBox?.Text, out var defaultTime))
+            {
+                SetCurrentValue(SelectedDateProperty, defaultTime);
+                _calendar?.MarkDates(startDate: defaultTime, endDate: defaultTime);
+            }
+        }
+        else
+        {
+            if (DateTime.TryParseExact(_textBox?.Text, DisplayFormat, CultureInfo.CurrentUICulture, DateTimeStyles.None,
+                    out var date))
+            {
+                SetCurrentValue(SelectedDateProperty, date);
+                _calendar?.MarkDates(startDate: date, endDate: date);
+            }
+        }
+    }
+
+    private void OnTextBoxGetFocus(object sender, GotFocusEventArgs e)
+    {
+        SetCurrentValue(IsDropdownOpenProperty, true); 
+    }
     
+    protected override void OnKeyDown(KeyEventArgs e)
+    {
+        if (e.Key == Key.Escape)
+        {
+            SetCurrentValue(IsDropdownOpenProperty, false);
+            e.Handled = true;
+            return;
+        }
+
+        if (e.Key == Key.Down)
+        {
+            SetCurrentValue(IsDropdownOpenProperty, true);
+            e.Handled = true;
+            return;
+        }
+
+        if (e.Key == Key.Tab)
+        {
+            SetCurrentValue(IsDropdownOpenProperty, false);
+            return;
+        }
+
+        base.OnKeyDown(e);
+    }
+
+    public void Clear()
+    {
+        
+    }
 }