using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;

namespace EleCho.WpfSuite
{
	/// <summary>
	/// ScrollViewer Utilities
	/// </summary>
	public static class ScrollViewerUtils
	{
		/// <summary>
		/// Get value of VerticalOffset property
		/// </summary>
		/// <param name="d"></param>
		/// <returns></returns>
		public static double GetVerticalOffset(DependencyObject d)
		{
			if (d is ScrollViewer sv)
			{
				return sv.VerticalOffset;
			}
			else if (d is ScrollContentPresenter scp)
			{
				return scp.VerticalOffset;
			}


			return (double)d.GetValue(VerticalOffsetProperty);
		}

		/// <summary>
		/// Set value of VerticalOffset property
		/// </summary>
		/// <param name="obj"></param>
		/// <param name="value"></param>
		public static void SetVerticalOffset(DependencyObject obj, double value)
		{
			obj.SetValue(VerticalOffsetProperty, value);
		}

		/// <summary>
		/// Get value of HorizontalOffset property
		/// </summary>
		/// <param name="d"></param>
		/// <returns></returns>
		public static double GetHorizontalOffset(DependencyObject d)
		{
			if (d is ScrollViewer sv)
			{
				return sv.HorizontalOffset;
			}
			else if (d is ScrollContentPresenter scp)
			{
				return scp.HorizontalOffset;
			}

			return (double)d.GetValue(HorizontalOffsetProperty);
		}

		/// <summary>
		/// Set value of HorizontalOffset property
		/// </summary>
		/// <param name="obj"></param>
		/// <param name="value"></param>
		public static void SetHorizontalOffset(DependencyObject obj, double value)
		{
			obj.SetValue(HorizontalOffsetProperty, value);
		}


		/// <summary>
		/// The DependencyProperty of VerticalOffset property
		/// </summary>
		public static readonly DependencyProperty VerticalOffsetProperty =
			DependencyProperty.RegisterAttached("VerticalOffset", typeof(double), typeof(ScrollViewerUtils), new PropertyMetadata(0.0, VerticalOffsetChangedCallback));

		/// <summary>
		/// The DependencyProperty of HorizontalOffset property
		/// </summary>
		public static readonly DependencyProperty HorizontalOffsetProperty =
			DependencyProperty.RegisterAttached("HorizontalOffset", typeof(double), typeof(ScrollViewerUtils), new PropertyMetadata(0.0, HorizontalOffsetChangedCallback));


		private static void VerticalOffsetChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
		{
			if (e.NewValue is not double offset)
			{
				return;
			}

			if (d is ScrollViewer sv)
			{
				sv.ScrollToVerticalOffset(offset);
			}
			else if (d is ScrollContentPresenter scp)
			{
				scp.SetVerticalOffset(offset);
			}
		}

		private static void HorizontalOffsetChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
		{
			if (e.NewValue is not double offset)
			{
				return;
			}

			if (d is ScrollViewer sv)
			{
				sv.ScrollToHorizontalOffset(offset);
			}
			else if (d is ScrollContentPresenter scp)
			{
				scp.SetHorizontalOffset(offset);
			}
		}
	}
}