using System;
namespace Terminal.Gui {
	/// <summary>
	/// 
	/// </summary>
	/// <remarks>
	/// <para>
	///   The subviews that are added to this scrollview are offset by the
	///   ContentOffset property.   The view itself is a window into the 
	///   space represented by the ContentSize.
	/// </para>
	/// <para>
	///   
	/// </para>
	/// </remarks>
	public class ScrollView : View {
		View contentView;

		public ScrollView (Rect frame) : base (frame)
		{
			contentView = new View (frame);
			base.Add (contentView);
		}

		Size contentSize;
		Point contentOffset;
		bool showHorizontalScrollIndicator;
		bool showVerticalScrollIndicator;

		/// <summary>
		/// Represents the contents of the data shown inside the scrolview
		/// </summary>
		/// <value>The size of the content.</value>
		public Size ContentSize {
			get {
				return contentSize;
			}
			set {
				contentSize = value;
				contentView.Frame = new Rect (contentOffset, value);
			}
		}

		/// <summary>
		/// Represents the top left corner coordinate that is displayed by the scrollview
		/// </summary>
		/// <value>The content offset.</value>
		public Point ContentOffset {
			get {
				return contentOffset;
			}
			set {
				contentOffset = new Point (-value.X, -value.Y);
				contentView.Frame = new Rect (contentOffset, contentSize);
			}
		}

		/// <summary>
		/// Adds the view to the scrollview.
		/// </summary>
		/// <param name="view">The view to add to the scrollview.</param>
		public override void Add (View view)
		{
			contentView.Add (view);
		}

		/// <summary>
		/// Gets or sets the visibility for the horizontal scroll indicator.
		/// </summary>
		/// <value><c>true</c> if show vertical scroll indicator; otherwise, <c>false</c>.</value>
		public bool ShowHorizontalScrollIndicator {
			get => showHorizontalScrollIndicator;
			set {
				showHorizontalScrollIndicator = value;
				SetNeedsDisplay ();
			}
		}


		/// <summary>
		/// /// Gets or sets the visibility for the vertical scroll indicator.
		/// </summary>
		/// <value><c>true</c> if show vertical scroll indicator; otherwise, <c>false</c>.</value>
		public bool ShowVerticalScrollIndicator {
			get => showVerticalScrollIndicator;
			set {
				showVerticalScrollIndicator = value;
				SetNeedsDisplay ();
			}
		}

		/// <summary>
		/// This event is raised when the contents have scrolled
		/// </summary>
		public event Action<ScrollView> Scrolled;

		public override void Redraw(Rect region)
		{
			var oldClip = ClipToBounds ();
			base.Redraw(region);
			Driver.SetAttribute (ColorScheme.Normal);

			DrawFrame (Bounds);
			Driver.Clip = oldClip;
		}
	}
}