using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Tango.DragAndDrop;

namespace Tango.Touch.Controls
{
    public class TouchScrollViewer : ScrollViewer
    {
        private double _position;
        private bool _fixed;

        static TouchScrollViewer()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(TouchScrollViewer), new FrameworkPropertyMetadata(typeof(TouchScrollViewer)));
        }

        //public TouchScrollViewer()
        //{
        //    this.RegisterForPreviewMouseOrTouchDown((_, e) => 
        //    {
        //        if (e.OriginalSource.GetType() == typeof(DragThumb))
        //        {
        //            e.Handled = true;
        //            return;
        //        }
        //    });
        //}

        public void FixPosition()
        {
            _position = VerticalOffset;
            _fixed = true;
        }

        public void ReleasePosition()
        {
            _fixed = false;
        }

        public TouchScrollViewer()
        {
            AddHandler(PreviewTouchUpEvent, new EventHandler<TouchEventArgs>(async (_, __) =>
            {
                await Task.Delay(250);
                ReleasePosition();
            }), true);
        }

        protected override void OnScrollChanged(ScrollChangedEventArgs e)
        {
            if (_fixed)
            {
                ScrollToVerticalOffset(_position);
            }
        }
    }
}