// <file>
//     <copyright see="prj:///doc/copyright.txt"/>
//     <license see="prj:///doc/license.txt"/>
//     <owner name="Daniel Grunwald" email="daniel@danielgrunwald.de"/>
//     <version>$Revision$</version>
// </file>

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;

using ICSharpCode.WpfDesign.Adorners;
using ICSharpCode.WpfDesign.Designer.Controls;

namespace ICSharpCode.WpfDesign.Designer
{
	sealed class DesignPanel : Decorator, IDesignPanel
	{
		#region Hit Testing
		/// <summary>
		/// this element is always hit (unless HitTestVisible is set to false)
		/// </summary>
		sealed class EatAllHitTestRequests : UIElement
		{
			protected override GeometryHitTestResult HitTestCore(GeometryHitTestParameters hitTestParameters)
			{
				return new GeometryHitTestResult(this, IntersectionDetail.FullyContains);
			}
			
			protected override HitTestResult HitTestCore(PointHitTestParameters hitTestParameters)
			{
				return new PointHitTestResult(this, hitTestParameters.HitPoint);
			}
		}
		
		static void RunHitTest(Visual reference, Point point, HitTestFilterCallback filterCallback, HitTestResultCallback resultCallback)
		{
			VisualTreeHelper.HitTest(reference, filterCallback, resultCallback,
			                         new PointHitTestParameters(point));
		}
		
		static HitTestFilterBehavior FilterHitTestInvisibleElements(DependencyObject potentialHitTestTarget)
		{
			UIElement element = potentialHitTestTarget as UIElement;
			if (element != null) {
				if (!(element.IsHitTestVisible && element.Visibility == Visibility.Visible)) {
					return HitTestFilterBehavior.ContinueSkipSelfAndChildren;
				}
			}
			return HitTestFilterBehavior.Continue;
		}
		
		/// <summary>
		/// Performs a custom hit testing lookup for the specified mouse event args.
		/// </summary>
		public DesignPanelHitTestResult HitTest(Point mousePosition, bool testAdorners, bool testDesignSurface)
		{
			DesignPanelHitTestResult result = DesignPanelHitTestResult.NoHit;
			HitTest(mousePosition, testAdorners, testDesignSurface,
			        delegate(DesignPanelHitTestResult r) {
			        	result = r;
			        	return false;
			        });
			return result;
		}
		
		/// <summary>
		/// Performs a hit test on the design surface, raising <paramref name="callback"/> for each match.
		/// Hit testing continues while the callback returns true.
		/// </summary>
		public void HitTest(Point mousePosition, bool testAdorners, bool testDesignSurface, Predicate<DesignPanelHitTestResult> callback)
		{
			if (mousePosition.X < 0 || mousePosition.Y < 0 || mousePosition.X > this.RenderSize.Width || mousePosition.Y > this.RenderSize.Height) {
				return;
			}
			// First try hit-testing on the adorner layer.
			
			bool continueHitTest = true;
			
			if (testAdorners) {
				RunHitTest(
					_adornerLayer, mousePosition, FilterHitTestInvisibleElements,
					delegate(HitTestResult result) {
						if (result != null && result.VisualHit != null && result.VisualHit is Visual) {
							DesignPanelHitTestResult customResult = new DesignPanelHitTestResult((Visual)result.VisualHit);
							DependencyObject obj = result.VisualHit;
							while (obj != null && obj != _adornerLayer) {
								AdornerPanel adorner = obj as AdornerPanel;
								if (adorner != null) {
									customResult.AdornerHit = adorner;
								}
								obj = VisualTreeHelper.GetParent(obj);
							}
							continueHitTest = callback(customResult);
							return continueHitTest ? HitTestResultBehavior.Continue : HitTestResultBehavior.Stop;
						} else {
							return HitTestResultBehavior.Continue;
						}
					});
			}
			
			if (continueHitTest && testDesignSurface) {
				RunHitTest(
					this.Child, mousePosition, delegate { return HitTestFilterBehavior.Continue; },
					delegate(HitTestResult result) {
						if (result != null && result.VisualHit != null && result.VisualHit is Visual) {
							DesignPanelHitTestResult customResult = new DesignPanelHitTestResult((Visual)result.VisualHit);
							
							ViewService viewService = _context.Services.View;
							DependencyObject obj = result.VisualHit;
							while (obj != null) {
								if ((customResult.ModelHit = viewService.GetModel(obj)) != null)
									break;
								obj = VisualTreeHelper.GetParent(obj);
							}
							if (customResult.ModelHit == null) {
								customResult.ModelHit = _context.RootItem;
							}
							continueHitTest = callback(customResult);
							return continueHitTest ? HitTestResultBehavior.Continue : HitTestResultBehavior.Stop;
						} else {
							return HitTestResultBehavior.Continue;
						}
					}
				);
			}
		}
		#endregion
		
		#region Fields + Constructor
		DesignContext _context;
		readonly EatAllHitTestRequests _eatAllHitTestRequests;
		readonly AdornerLayer _adornerLayer;
		
		public DesignPanel()
		{
			this.Focusable = true;
			this.AllowDrop = true;
			DesignerProperties.SetIsInDesignMode(this, true);
			
			_eatAllHitTestRequests = new EatAllHitTestRequests();
			_eatAllHitTestRequests.MouseDown += delegate {
				// ensure the design panel has focus while the user is interacting with it
				this.Focus();
			};
			_eatAllHitTestRequests.AllowDrop = true;
			_adornerLayer = new AdornerLayer(this);
		}
		#endregion
		
		#region Properties
		
		/// <summary>
		/// Gets/Sets the design context.
		/// </summary>
		public DesignContext Context {
			get { return _context; }
			set { _context = value; }
		}
		
		public ICollection<AdornerPanel> Adorners {
			get {
				return _adornerLayer.Adorners;
			}
		}
		
		/// <summary>
		/// Gets/Sets if the design content is visible for hit-testing purposes.
		/// </summary>
		public bool IsContentHitTestVisible {
			get { return !_eatAllHitTestRequests.IsHitTestVisible; }
			set { _eatAllHitTestRequests.IsHitTestVisible = !value; }
		}
		
		/// <summary>
		/// Gets/Sets if the adorner layer is visible for hit-testing purposes.
		/// </summary>
		public bool IsAdornerLayerHitTestVisible {
			get { return _adornerLayer.IsHitTestVisible; }
			set { _adornerLayer.IsHitTestVisible = value; }
		}
		
		#endregion
		
		#region Visual Child Management
		public override UIElement Child {
			get { return base.Child; }
			set {
				if (base.Child == value)
					return;
				if (value == null) {
					// Child is being set from some value to null
					
					// remove _adornerLayer and _eatAllHitTestRequests
					RemoveVisualChild(_adornerLayer);
					RemoveVisualChild(_eatAllHitTestRequests);
				} else if (base.Child == null) {
					// Child is being set from null to some value
					AddVisualChild(_adornerLayer);
					AddVisualChild(_eatAllHitTestRequests);
				}
				base.Child = value;
			}
		}
		
		protected override Visual GetVisualChild(int index)
		{
			if (base.Child != null) {
				if (index == 0)
					return base.Child;
				else if (index == 1)
					return _eatAllHitTestRequests;
				else if (index == 2)
					return _adornerLayer;
			}
			return base.GetVisualChild(index);
		}
		
		protected override int VisualChildrenCount {
			get {
				if (base.Child != null)
					return 3;
				else
					return base.VisualChildrenCount;
			}
		}
		
		protected override Size MeasureOverride(Size constraint)
		{
			Size result = base.MeasureOverride(constraint);
			if (this.Child != null) {
				_adornerLayer.Measure(constraint);
				_eatAllHitTestRequests.Measure(constraint);
			}
			return result;
		}
		
		protected override Size ArrangeOverride(Size arrangeSize)
		{
			Size result = base.ArrangeOverride(arrangeSize);
			if (this.Child != null) {
				Rect r = new Rect(new Point(0, 0), arrangeSize);
				_adornerLayer.Arrange(r);
				_eatAllHitTestRequests.Arrange(r);
			}
			return result;
		}
		#endregion
		
		protected override void OnQueryCursor(QueryCursorEventArgs e)
		{
			base.OnQueryCursor(e);
			if (_context != null) {
				Cursor cursor = _context.Services.Tool.CurrentTool.Cursor;
				if (cursor != null) {
					e.Cursor = cursor;
					e.Handled = true;
				}
			}
		}
	}
}