// --------------------------------------------------------------------------------------------------------------------

// <copyright file="Visual3DHelper.cs" company="Helix 3D Toolkit">

//   http://helixtoolkit.codeplex.com, license: Ms-PL

// </copyright>

// --------------------------------------------------------------------------------------------------------------------



namespace HelixToolkit.Wpf

{

    using System;

    using System.Collections.Generic;

    using System.Linq;

    using System.Reflection;

    using System.Windows;

    using System.Windows.Controls;

    using System.Windows.Media;

    using System.Windows.Media.Media3D;



    /// <summary>

    /// Helper methods for <see cref="Visual3D"/> objects.

    /// </summary>

    public static class Visual3DHelper

    {

        #region Constants and Fields



        /// <summary>

        /// The visual 3 d model property info.

        /// </summary>

        private static readonly PropertyInfo Visual3DModelPropertyInfo = typeof(Visual3D).GetProperty(

            "Visual3DModel", BindingFlags.Instance | BindingFlags.NonPublic);



        #endregion



        #region Public Methods



        /// <summary>

        /// Finds a child of the specified type.

        /// </summary>

        /// <typeparam name="T">

        /// </typeparam>

        /// <param name="parent">

        /// The parent.

        /// </param>

        /// <returns>

        /// </returns>

        public static T Find<T>(DependencyObject parent) where T : DependencyObject

        {

            // todo: this should be improved

            foreach (DependencyObject d in LogicalTreeHelper.GetChildren(parent))

            {

                var a = Find<T>(d);

                if (a != null)

                {

                    return a;

                }

            }



            var model = parent as ModelVisual3D;

            if (model != null)

            {

                var modelgroup = model.Content as Model3DGroup;

                if (modelgroup != null)

                {

                    return modelgroup.Children.OfType<T>().FirstOrDefault();

                }

            }



            return null;

        }



        /// <summary>

        /// Finds the bounding box for a collection of Visual3Ds.

        /// </summary>

        /// <param name="children">

        /// The children.

        /// </param>

        /// <returns>

        /// </returns>

        public static Rect3D FindBounds(Visual3DCollection children)

        {

            var bounds = Rect3D.Empty;

            foreach (var visual in children)

            {

                var b = FindBounds(visual, Transform3D.Identity);

                bounds.Union(b);

            }



            return bounds;

        }



        /// <summary>

        /// Finds the bounding box for the specified visual.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <param name="transform">

        /// The transform of visual.

        /// </param>

        /// <returns>

        /// </returns>

        public static Rect3D FindBounds(Visual3D visual, Transform3D transform)

        {

            var bounds = Rect3D.Empty;

            var childTransform = Transform3DHelper.CombineTransform(visual.Transform, transform);

            var model = GetModel(visual);

            if (model != null)

            {

                // apply transform

                var transformedBounds = childTransform.TransformBounds(model.Bounds);

                if (!double.IsNaN(transformedBounds.X))

                {

                    bounds.Union(transformedBounds);

                }

            }



            foreach (var child in GetChildren(visual))

            {

                var b = FindBounds(child, childTransform);

                bounds.Union(b);

            }



            return bounds;

        }



        /// <summary>

        /// Gets the transform for the specified visual.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <returns>

        /// </returns>

        public static Matrix3D GetTransform(Visual3D visual)

        {

            var totalTransform = Matrix3D.Identity;



            DependencyObject obj = visual;

            while (obj != null)

            {

                var viewport3DVisual = obj as Viewport3DVisual;

                if (viewport3DVisual != null)

                {

                    return totalTransform;

                }



                var mv = obj as ModelVisual3D;

                if (mv != null)

                {

                    if (mv.Transform != null)

                    {

                        totalTransform.Append(mv.Transform.Value);

                    }

                }



                obj = VisualTreeHelper.GetParent(obj);

            }



            throw new InvalidOperationException("The visual is not added to a Viewport3D.");

        }



        /// <summary>

        /// Gets the Viewport3D from the specified visual.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <returns>

        /// The Viewport3D

        /// </returns>

        public static Viewport3D GetViewport3D(Visual3D visual)

        {

            DependencyObject obj = visual;

            while (obj != null)

            {

                var vis = obj as Viewport3DVisual;

                if (vis != null)

                {

                    return VisualTreeHelper.GetParent(obj) as Viewport3D;

                }



                obj = VisualTreeHelper.GetParent(obj);

            }



            return null;

        }



        /// <summary>

        /// Gets the transform to viewport space.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <returns>

        /// A transformation matrix.

        /// </returns>

        public static Matrix3D GetViewportTransform(Visual3D visual)

        {

            var totalTransform = Matrix3D.Identity;



            DependencyObject obj = visual;

            while (obj != null)

            {

                var viewport3DVisual = obj as Viewport3DVisual;

                if (viewport3DVisual != null)

                {

                    var matxViewport = Viewport3DHelper.GetTotalTransform(viewport3DVisual);

                    totalTransform.Append(matxViewport);

                    return totalTransform;

                }



                var mv = obj as ModelVisual3D;

                if (mv != null)

                {

                    if (mv.Transform != null)

                    {

                        totalTransform.Append(mv.Transform.Value);

                    }

                }



                obj = VisualTreeHelper.GetParent(obj);

            }



            throw new InvalidOperationException("The visual is not added to a Viewport3D.");



            // At this point, we know obj is Viewport3DVisual

        }



        /// <summary>

        /// Determines whether the visual is attached to a Viewport3D.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <returns>

        /// The is attached to viewport 3 d.

        /// </returns>

        public static bool IsAttachedToViewport3D(Visual3D visual)

        {

            DependencyObject obj = visual;

            while (obj != null)

            {

                var vis = obj as Viewport3DVisual;

                if (vis != null)

                {

                    return true;

                }



                obj = VisualTreeHelper.GetParent(obj);

            }



            return false;

        }



        /// <summary>

        /// Traverses the Visual3D/Model3D tree. Run the specified action for each Model3D.

        /// </summary>

        /// <typeparam name="T">

        /// </typeparam>

        /// <param name="visuals">

        /// The visuals.

        /// </param>

        /// <param name="action">

        /// The action.

        /// </param>

        public static void Traverse<T>(Visual3DCollection visuals, Action<T, Transform3D> action) where T : Model3D

        {

            foreach (var child in visuals)

            {

                Traverse(child, action);

            }

        }



        /// <summary>

        /// Traverses the Visual3D/Model3D tree. Run the specified action for each Model3D.

        /// </summary>

        /// <typeparam name="T">

        /// </typeparam>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <param name="action">

        /// The action.

        /// </param>

        public static void Traverse<T>(Visual3D visual, Action<T, Transform3D> action) where T : Model3D

        {

            Traverse(visual, Transform3D.Identity, action);

        }



        /// <summary>

        /// Traverses the Model3D tree. Run the specified action for each Model3D.

        /// </summary>

        /// <typeparam name="T">

        /// </typeparam>

        /// <param name="model">

        /// The model.

        /// </param>

        /// <param name="action">

        /// The action.

        /// </param>

        public static void TraverseModel<T>(Model3D model, Action<T, Transform3D> action) where T : Model3D

        {

            TraverseModel(model, Transform3D.Identity, action);

        }



        /// <summary>

        /// Traverses the Model3D tree. Run the specified action for each Model3D.

        /// </summary>

        /// <typeparam name="T">

        /// </typeparam>

        /// <param name="model">

        /// The model.

        /// </param>

        /// <param name="transform">

        /// The transform.

        /// </param>

        /// <param name="action">

        /// The action.

        /// </param>

        public static void TraverseModel<T>(Model3D model, Transform3D transform, Action<T, Transform3D> action)

            where T : Model3D

        {

            var mg = model as Model3DGroup;

            if (mg != null)

            {

                var childTransform = Transform3DHelper.CombineTransform(model.Transform, transform);

                foreach (var m in mg.Children)

                {

                    TraverseModel(m, childTransform, action);

                }

            }



            var gm = model as T;

            if (gm != null)

            {

                var childTransform = Transform3DHelper.CombineTransform(model.Transform, transform);

                action(gm, childTransform);

            }

        }



        #endregion



        #region Methods



        /// <summary>

        /// Gets the children.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <returns>

        /// </returns>

        private static IEnumerable<Visual3D> GetChildren(Visual3D visual)

        {

            int n = VisualTreeHelper.GetChildrenCount(visual);

            for (int i = 0; i < n; i++)

            {

                var child = VisualTreeHelper.GetChild(visual, i) as Visual3D;

                if (child == null)

                {

                    continue;

                }



                yield return child;

            }

        }



        /// <summary>

        /// Gets the model for the specified Visual3D.

        /// </summary>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <returns>

        /// </returns>

        private static Model3D GetModel(Visual3D visual)

        {

            Model3D model;

            var mv = visual as ModelVisual3D;

            if (mv != null)

            {

                model = mv.Content;

            }

            else

            {

                model = Visual3DModelPropertyInfo.GetValue(visual, null) as Model3D;

            }



            return model;

        }



        /// <summary>

        /// Traverses the specified visual.

        /// </summary>

        /// <typeparam name="T">

        /// </typeparam>

        /// <param name="visual">

        /// The visual.

        /// </param>

        /// <param name="transform">

        /// The transform.

        /// </param>

        /// <param name="action">

        /// The action.

        /// </param>

        private static void Traverse<T>(Visual3D visual, Transform3D transform, Action<T, Transform3D> action)

            where T : Model3D

        {

            var childTransform = Transform3DHelper.CombineTransform(visual.Transform, transform);

            var model = GetModel(visual);

            if (model != null)

            {

                TraverseModel(model, childTransform, action);

            }



            foreach (var child in GetChildren(visual))

            {

                Traverse(child, childTransform, action);

            }

        }



        #endregion

    }

}