#region License
/*
MIT License
Copyright © 2006 The Mono.Xna Team

All rights reserved.

Authors:
Olivier Dufour (Duff)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#endregion License

using System;
using System.Collections.Generic;
using System.Globalization;
using System.ComponentModel;

namespace Microsoft.Xna.Framework
{
    public struct BoundingSphere : IEquatable<BoundingSphere>
    {
        #region Public Fields

        public Vector3 Center;
        public float Radius;

        #endregion Public Fields


        #region Constructors

        public BoundingSphere(Vector3 center, float radius)
        {
            this.Center = center;
            this.Radius = radius;
        }

        #endregion Constructors


        #region Public Methods

        public BoundingSphere Transform(Matrix matrix)
        {
            BoundingSphere sphere = new BoundingSphere();
            sphere.Center = Vector3.Transform(this.Center, matrix);
            sphere.Radius = this.Radius * ((float)Math.Sqrt((double)Math.Max(((matrix.M11 * matrix.M11) + (matrix.M12 * matrix.M12)) + (matrix.M13 * matrix.M13), Math.Max(((matrix.M21 * matrix.M21) + (matrix.M22 * matrix.M22)) + (matrix.M23 * matrix.M23), ((matrix.M31 * matrix.M31) + (matrix.M32 * matrix.M32)) + (matrix.M33 * matrix.M33)))));
            return sphere;
        }

        public void Transform(ref Matrix matrix, out BoundingSphere result)
        {
            result.Center = Vector3.Transform(this.Center, matrix);
            result.Radius = this.Radius * ((float)Math.Sqrt((double)Math.Max(((matrix.M11 * matrix.M11) + (matrix.M12 * matrix.M12)) + (matrix.M13 * matrix.M13), Math.Max(((matrix.M21 * matrix.M21) + (matrix.M22 * matrix.M22)) + (matrix.M23 * matrix.M23), ((matrix.M31 * matrix.M31) + (matrix.M32 * matrix.M32)) + (matrix.M33 * matrix.M33)))));
        }

        public ContainmentType Contains(BoundingBox box)
        {
            //check if all corner is in sphere
            bool inside = true;
            foreach (Vector3 corner in box.GetCorners())
            {
                if (this.Contains(corner) == ContainmentType.Disjoint)
                {
                    inside = false;
                    break;
                }
            }

            if (inside)
                return ContainmentType.Contains;

            //check if the distance from sphere center to cube face < radius
            double dmin = 0;

            if (Center.X < box.Min.X)
				dmin += (Center.X - box.Min.X) * (Center.X - box.Min.X);

			else if (Center.X > box.Max.X)
					dmin += (Center.X - box.Max.X) * (Center.X - box.Max.X);

			if (Center.Y < box.Min.Y)
				dmin += (Center.Y - box.Min.Y) * (Center.Y - box.Min.Y);

			else if (Center.Y > box.Max.Y)
				dmin += (Center.Y - box.Max.Y) * (Center.Y - box.Max.Y);

			if (Center.Z < box.Min.Z)
				dmin += (Center.Z - box.Min.Z) * (Center.Z - box.Min.Z);

			else if (Center.Z > box.Max.Z)
				dmin += (Center.Z - box.Max.Z) * (Center.Z - box.Max.Z);

			if (dmin <= Radius * Radius) 
				return ContainmentType.Intersects;
            
            //else disjoint
            return ContainmentType.Disjoint;

        }

        public void Contains(ref BoundingBox box, out ContainmentType result)
        {
            result = this.Contains(box);
        }

        public ContainmentType Contains(BoundingFrustum frustum)
        {
            //check if all corner is in sphere
            bool inside = true;

            Vector3[] corners = frustum.GetCorners();
            foreach (Vector3 corner in corners)
            {
                if (this.Contains(corner) == ContainmentType.Disjoint)
                {
                    inside = false;
                    break;
                }
            }
            if (inside)
                return ContainmentType.Contains;

            //check if the distance from sphere center to frustrum face < radius
            double dmin = 0;
            //TODO : calcul dmin

            if (dmin <= Radius * Radius)
                return ContainmentType.Intersects;

            //else disjoint
            return ContainmentType.Disjoint;
        }

        public ContainmentType Contains(BoundingSphere sphere)
        {
            float val = Vector3.Distance(sphere.Center, Center);

            if (val > sphere.Radius + Radius)
                return ContainmentType.Disjoint;

            else if (val <= Radius - sphere.Radius)
                return ContainmentType.Contains;

            else
                return ContainmentType.Intersects;
        }

        public void Contains(ref BoundingSphere sphere, out ContainmentType result)
        {
            result = Contains(sphere);
        }

        public ContainmentType Contains(Vector3 point)
        {
            float distance = Vector3.Distance(point, Center);

            if (distance > this.Radius)
                return ContainmentType.Disjoint;

            else if (distance < this.Radius)
                return ContainmentType.Contains;

            return ContainmentType.Intersects;
        }

        public void Contains(ref Vector3 point, out ContainmentType result)
        {
            result = Contains(point);
        }

        public static BoundingSphere CreateFromBoundingBox(BoundingBox box)
        {
            // Find the center of the box.
            Vector3 center = new Vector3((box.Min.X + box.Max.X) / 2.0f,
                                         (box.Min.Y + box.Max.Y) / 2.0f,
                                         (box.Min.Z + box.Max.Z) / 2.0f);

            // Find the distance between the center and one of the corners of the box.
            float radius = Vector3.Distance(center, box.Max);

            return new BoundingSphere(center, radius);
        }

        public static void CreateFromBoundingBox(ref BoundingBox box, out BoundingSphere result)
        {
            result = CreateFromBoundingBox(box);
        }

        public static BoundingSphere CreateFromFrustum(BoundingFrustum frustum)
        {
            return BoundingSphere.CreateFromPoints(frustum.GetCorners());
        }

        public static BoundingSphere CreateFromPoints(IEnumerable<Vector3> points)
        {
            if (points == null)
                throw new ArgumentNullException("points");

            float radius = 0;
            Vector3 center = new Vector3();
            // First, we'll find the center of gravity for the point 'cloud'.
            int num_points = 0; // The number of points (there MUST be a better way to get this instead of counting the number of points one by one?)
            
            foreach (Vector3 v in points)
            {
                center += v;    // If we actually knew the number of points, we'd get better accuracy by adding v / num_points.
                ++num_points;
            }
            
            center /= (float)num_points;

            // Calculate the radius of the needed sphere (it equals the distance between the center and the point further away).
            foreach (Vector3 v in points)
            {
                float distance = ((Vector3)(v - center)).Length();
                
                if (distance > radius)
                    radius = distance;
            }

            return new BoundingSphere(center, radius);
        }

        public static BoundingSphere CreateMerged(BoundingSphere original, BoundingSphere additional)
        {
            Vector3 ocenterToaCenter = Vector3.Subtract(additional.Center, original.Center);
            float distance = ocenterToaCenter.Length();
            if (distance <= original.Radius + additional.Radius)//intersect
            {
                if (distance <= original.Radius - additional.Radius)//original contain additional
                    return original;
                if (distance <= additional.Radius - original.Radius)//additional contain original
                    return additional;
            }

            //else find center of new sphere and radius
            float leftRadius = Math.Max(original.Radius - distance, additional.Radius);
            float Rightradius = Math.Max(original.Radius + distance, additional.Radius);
            ocenterToaCenter = ocenterToaCenter + (((leftRadius - Rightradius) / (2 * ocenterToaCenter.Length())) * ocenterToaCenter);//oCenterToResultCenter
            
            BoundingSphere result = new BoundingSphere();
            result.Center = original.Center + ocenterToaCenter;
            result.Radius = (leftRadius + Rightradius) / 2;
            return result;
        }

        public static void CreateMerged(ref BoundingSphere original, ref BoundingSphere additional, out BoundingSphere result)
        {
            result = BoundingSphere.CreateMerged(original, additional);
        }

        public bool Equals(BoundingSphere other)
        {
            return this.Center == other.Center && this.Radius == other.Radius;
        }

        public override bool Equals(object obj)
        {
            if (obj is BoundingSphere)
                return this.Equals((BoundingSphere)obj);

            return false;
        }

        public override int GetHashCode()
        {
            return this.Center.GetHashCode() + this.Radius.GetHashCode();
        }

        public bool Intersects(BoundingBox box)
        {
			return box.Intersects(this);
        }

        public void Intersects(ref BoundingBox box, out bool result)
        {
			result = Intersects(box);
        }

        public bool Intersects(BoundingFrustum frustum)
        {
            if (frustum == null)
                throw new NullReferenceException();

            throw new NotImplementedException();
        }

        public bool Intersects(BoundingSphere sphere)
        {
            float val = Vector3.Distance(sphere.Center, Center);
			if (val > sphere.Radius + Radius)
				return false;
			return true;
        }

        public void Intersects(ref BoundingSphere sphere, out bool result)
        {
			result = Intersects(sphere);
        }

        public PlaneIntersectionType Intersects(Plane plane)
        {
			float distance = Vector3.Dot(plane.Normal, this.Center) + plane.D;
			if (distance > this.Radius)
				return PlaneIntersectionType.Front;
			if (distance < -this.Radius)
				return PlaneIntersectionType.Back;
			//else it intersect
			return PlaneIntersectionType.Intersecting;
        }

        public void Intersects(ref Plane plane, out PlaneIntersectionType result)
        {
			result = Intersects(plane);
        }

        public Nullable<float> Intersects(Ray ray)
        {
            return ray.Intersects(this);
        }

        public void Intersects(ref Ray ray, out Nullable<float> result)
        {
			result = Intersects(ray);
        }

        public static bool operator == (BoundingSphere a, BoundingSphere b)
        {
            return a.Equals(b);
        }

        public static bool operator != (BoundingSphere a, BoundingSphere b)
        {
            return !a.Equals(b);
        }

        public override string ToString()
        {
            return string.Format(CultureInfo.CurrentCulture, "{{Center:{0} Radius:{1}}}", this.Center.ToString(), this.Radius.ToString());
        }

        #endregion Public Methods
    }
}