using System;
using System.Xml;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections.Generic;

using System.Windows;
using System.Windows.Media;

using SharpVectors.Dom.Svg;
using SharpVectors.Runtime;
using SharpVectors.Renderers.Utils;

namespace SharpVectors.Renderers.Wpf
{
    public sealed class WpfSvgRendering : WpfRendering
    {
        #region Private Fields

        private DrawingGroup _drawGroup;

        #endregion

        #region Constructors and Destructor

        public WpfSvgRendering(SvgElement element)
            : base(element)
        {
        }

        #endregion

        #region Public Methods

        public override void BeforeRender(WpfDrawingRenderer renderer)
        {
            base.BeforeRender(renderer);

            WpfDrawingContext context = renderer.Context;
            _drawGroup = new DrawingGroup();

            if (context.Count == 0)
            {
                context.Push(_drawGroup);
                context.Root = _drawGroup;
            }
            else if (context.Count == 1)
            {        
                DrawingGroup currentGroup = context.Peek();

                if (currentGroup == null)
                {
                    throw new InvalidOperationException("An existing group is expected.");
                }
                if (currentGroup == context.Root && !context.IsFragment)
                {
                    _drawGroup.SetValue(FrameworkElement.NameProperty, SvgObject.DrawLayer);
                    if (context.IncludeRuntime)
                    {
                        SvgLink.SetKey(_drawGroup, SvgObject.DrawLayer);
                    }
                }

                currentGroup.Children.Add(_drawGroup);
                context.Push(_drawGroup);
            }
            else
            {
                DrawingGroup currentGroup = context.Peek();

                if (currentGroup == null)
                {
                    throw new InvalidOperationException("An existing group is expected.");
                }

                currentGroup.Children.Add(_drawGroup);
                context.Push(_drawGroup);
            }

            SvgSvgElement svgElm = (SvgSvgElement)_svgElement;

            double x      = Math.Round(svgElm.X.AnimVal.Value,      4);
            double y      = Math.Round(svgElm.Y.AnimVal.Value,      4);
            double width  = Math.Round(svgElm.Width.AnimVal.Value,  4);
            double height = Math.Round(svgElm.Height.AnimVal.Value, 4);

            Rect elmRect  = new Rect(x, y, width, height);

            //if (element.ParentNode is SvgElement)
            //{
            //    // TODO: should it be moved with x and y?
            //}

            XmlNode parentNode = _svgElement.ParentNode;

            //if (parentNode.NodeType == XmlNodeType.Document)
            {
                ISvgFitToViewBox fitToView = svgElm as ISvgFitToViewBox;
                if (fitToView != null)
                {
                    ISvgAnimatedRect animRect = fitToView.ViewBox;
                    if (animRect != null)
                    {
                        ISvgRect viewRect = animRect.AnimVal;
                        if (viewRect != null)
                        {
                            Rect wpfViewRect = WpfConvert.ToRect(viewRect);
                            if (!wpfViewRect.IsEmpty && wpfViewRect.Width > 0 && wpfViewRect.Height > 0)
                            {
                                elmRect = wpfViewRect;
                            }
                        }
                    }
                } 
            }

            Transform transform = null;
            if (parentNode.NodeType != XmlNodeType.Document)
            {
                FitToViewbox(context, elmRect);

                transform = this.Transform;
                if (transform != null)
                {
                    _drawGroup.Transform = transform;
                }
            }

            //if (height > 0 && width > 0)
            //{
            //    ClipGeometry = new RectangleGeometry(elmRect);
            //}
            //Geometry clipGeom = this.ClipGeometry;
            //if (clipGeom != null)
            //{
            //    _drawGroup.ClipGeometry = clipGeom;
            //}

            if (((float)elmRect.Width != 0 && (float)elmRect.Height != 0))
            {   
                // Elements such as "pattern" are also rendered by this renderer, so we make sure we are
                // dealing with the root SVG element...
                if (parentNode != null && parentNode.NodeType == XmlNodeType.Document)
                {
                    _drawGroup.ClipGeometry = new RectangleGeometry(elmRect);
                }
                else
                {
                    if (transform != null)
                    {
                        // We have already applied the transform, which will translate to the start point...
                        if (transform is TranslateTransform)
                        {
                            _drawGroup.ClipGeometry = new RectangleGeometry(
                                new Rect(0, 0, elmRect.Width, elmRect.Height));
                        }
                        else
                        {
                            _drawGroup.ClipGeometry = new RectangleGeometry(elmRect);
                        }
                    }
                    else
                    {
                        _drawGroup.ClipGeometry = new RectangleGeometry(elmRect);
                    }
                }

                //DrawingGroup animationGroup = context.Links;
                //if (animationGroup != null)
                //{
                //    animationGroup.ClipGeometry = clipGeom;
                //}
            }
        }

        public override void Render(WpfDrawingRenderer renderer)
        {
            base.Render(renderer);
        }

        public override void AfterRender(WpfDrawingRenderer renderer)
        {
            base.AfterRender(renderer);

            Debug.Assert(_drawGroup != null);

            WpfDrawingContext context = renderer.Context;

            DrawingGroup currentGroup = context.Peek();

            if (currentGroup == null || currentGroup != _drawGroup)
            {
                throw new InvalidOperationException("An existing group is expected.");
            }

            context.Pop();
        }

        #endregion
    }
}