using System.Text.RegularExpressions;
using System.Windows.Input;
using Xceed.Wpf.Toolkit;

namespace BreCalClient
{
    public class DateTimePickerExt : DateTimePicker
    {
        protected override void OnPreviewTextInput(TextCompositionEventArgs e)
        {
            base.OnPreviewTextInput(e);
            if (this.Template.FindName("PART_TextBox", this) is not WatermarkTextBox tb) return;

            // strip input after caret
            string subText = (tb.CaretIndex > 0) ? this.Text[..tb.CaretIndex] : tb.Text; // Range operator instead of Substring(0, tb.CaretIndex)
            string text = subText + e.Text;
            
            // System.Diagnostics.Debug.WriteLine("C:" + this.Text + " E: " + e.Text + " Caret: " + tb.CaretIndex + " Subt: " + subText);

            // 10 char eingabe "am Stück"
            if (Regex.IsMatch(text, @"^\d{10}"))
            {
                e.Handled = true;
                tb.Text = Regex.Replace(text, @"(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})", "$1.$2.20$3 $4:$5");
                tb.CaretIndex = tb.Text.Length;
                tb.SelectedText = "";
            }

            // nur die Zeit wird markiert und mit 4 Zahlen befüllt, diese Regel setzt den Doppelpunkt
            else if (Regex.IsMatch(text, @"^(\d{2}\.\d{2}\. \d{4}  \d{3})"))
            {
                e.Handled = true;
                tb.Text = Regex.Replace(text, @"(\d{2}\.\d{2}\. \d{4}  \d{2})(\d)(.*)", "$1:$2");
                // System.Diagnostics.Trace.WriteLine("Replaced: " + tb.Text);
                tb.CaretIndex = tb.Text.Length;
                tb.Select(tb.Text.Length, 0);
            }

        }
    }
}