/******************************************************************************
 *
 * The MIT License (MIT)
 *
 * LiquidVolumeFX.MIConvexHull, Copyright (c) 2015 David Sehnal, Matthew Campbell
 * 
 * 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.
 *  
 *****************************************************************************/

namespace LiquidVolumeFX.MIConvexHull
{
    /// <summary>
    /// For deferred face addition.
    /// </summary>
    internal sealed class DeferredFace
    {
        /// <summary>
        /// The faces.
        /// </summary>
        public ConvexFaceInternal Face, Pivot, OldFace;

        /// <summary>
        /// The indices.
        /// </summary>
        public int FaceIndex, PivotIndex;
    }

    /// <summary>
    /// A helper class used to connect faces.
    /// </summary>
    internal sealed class FaceConnector
    {
        /// <summary>
        /// The edge to be connected.
        /// </summary>
        public int EdgeIndex;

        /// <summary>
        /// The face.
        /// </summary>
        public ConvexFaceInternal Face;

        /// <summary>
        /// The hash code computed from indices.
        /// </summary>
        public uint HashCode;

        /// <summary>
        /// Next node in the list.
        /// </summary>
        public FaceConnector Next;

        /// <summary>
        /// Prev node in the list.
        /// </summary>
        public FaceConnector Previous;

        /// <summary>
        /// The vertex indices.
        /// </summary>
        public int[] Vertices;

        /// <summary>
        /// Ctor.
        /// </summary>
        /// <param name="dimension">The dimension.</param>
        public FaceConnector(int dimension)
        {
            Vertices = new int[dimension - 1];
        }

        /// <summary>
        /// Updates the connector.
        /// </summary>
        /// <param name="face">The face.</param>
        /// <param name="edgeIndex">Index of the edge.</param>
        /// <param name="dim">The dim.</param>
        public void Update(ConvexFaceInternal face, int edgeIndex, int dim)
        {
            Face = face;
            EdgeIndex = edgeIndex;

            uint hashCode = 23;

            unchecked
            {
                var vs = face.Vertices;
                int i, c = 0;
                for (i = 0; i < edgeIndex; i++)
                {
                    Vertices[c++] = vs[i];
                    hashCode += 31*hashCode + (uint) vs[i];
                }
                for (i = edgeIndex + 1; i < vs.Length; i++)
                {
                    Vertices[c++] = vs[i];
                    hashCode += 31*hashCode + (uint) vs[i];
                }
            }

            HashCode = hashCode;
        }

        /// <summary>
        /// Can two faces be connected.
        /// </summary>
        /// <param name="a">a.</param>
        /// <param name="b">The b.</param>
        /// <param name="dim">The dim.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
        public static bool AreConnectable(FaceConnector a, FaceConnector b, int dim)
        {
            if (a.HashCode != b.HashCode) return false;

            var av = a.Vertices;
            var bv = b.Vertices;
            for (var i = 0; i < av.Length; i++)
            {
                if (av[i] != bv[i]) return false;
            }

            return true;
        }

        /// <summary>
        /// Connect two faces.
        /// </summary>
        /// <param name="a">a.</param>
        /// <param name="b">The b.</param>
        public static void Connect(FaceConnector a, FaceConnector b)
        {
            a.Face.AdjacentFaces[a.EdgeIndex] = b.Face.Index;
            b.Face.AdjacentFaces[b.EdgeIndex] = a.Face.Index;
        }
    }

    /// <summary>
    /// This internal class manages the faces of the convex hull. It is a
    /// separate class from the desired user class.
    /// </summary>
    internal sealed class ConvexFaceInternal
    {
        /// <summary>
        /// Gets or sets the adjacent face data.
        /// </summary>
        public int[] AdjacentFaces;

        /// <summary>
        /// The furthest vertex.
        /// </summary>
        public int FurthestVertex;

        /// <summary>
        /// Index of the face inside the pool.
        /// </summary>
        public int Index;

        /// <summary>
        /// Is it present in the list.
        /// </summary>
        public bool InList;

        /// <summary>
        /// Is the normal flipped?
        /// </summary>
        public bool IsNormalFlipped;

        /// <summary>
        /// Next node in the list.
        /// </summary>
        public ConvexFaceInternal Next;

        /// <summary>
        /// Gets or sets the normal vector.
        /// </summary>
        public double[] Normal;

        /// <summary>
        /// Face plane constant element.
        /// </summary>
        public double Offset;

        //public int UnprocessedIndex;

        /// <summary>
        /// Prev node in the list.
        /// </summary>
        public ConvexFaceInternal Previous;

        /// <summary>
        /// Used to traverse affected faces and create the Delaunay representation.
        /// </summary>
        public int Tag;

        /// <summary>
        /// Gets or sets the vertices.
        /// </summary>
        public int[] Vertices;

        /// <summary>
        /// Gets or sets the vertices beyond.
        /// </summary>
        public IndexBuffer VerticesBeyond;

        /// <summary>
        /// Initializes a new instance of the <see cref="ConvexFaceInternal" /> class.
        /// </summary>
        /// <param name="dimension">The dimension.</param>
        /// <param name="index">The index.</param>
        /// <param name="beyondList">The beyond list.</param>
        public ConvexFaceInternal(int dimension, int index, IndexBuffer beyondList)
        {
            Index = index;
            AdjacentFaces = new int[dimension];
            VerticesBeyond = beyondList;
            Normal = new double[dimension];
            Vertices = new int[dimension];
        }
    }
}