//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="Matrix.cs"
// Project: StgSharp
// AuthorGroup: Nitload Space
// Copyright (c) Nitload Space. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person 
// obtaining a copy of this software and associated documentation 
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// 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. 
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// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using StgSharp.HighPerformance;
using System;
using System.Numerics;

using hlsfAllocator = global::StgSharp.HighPerformance.Memory.HybridLayerSegregatedFitAllocator;
using hlsfHandle = global::StgSharp.HighPerformance.Memory.HybridLayerSegregatedFitAllocationHandle;

namespace StgSharp.Mathematics
{
    public abstract unsafe partial class Matrix<T> where T: unmanaged, INumber<T>
    {

        private protected readonly int t_count = 16 / sizeof(T);

        private protected readonly int t_size = sizeof(T);

        private protected Matrix() { }

        public abstract ref T this[int column, int row]
        {
            get;
        }

        public abstract unsafe Matrix<T> this[ReadOnlySpan<MatrixIndex> column, ReadOnlySpan<MatrixIndex> row]
        {
            get;
            set;
        }

        public int ColumnCount { get; init; }

        public int RowCount { get; init; }

        protected int KernelColumnCount { get; init; }

        protected int KernelRowCount { get; init; }

        public abstract ref MatrixKernel GetMatrixKernel(int column, int row);

        [Obsolete("This method does not contain boarder check, so be careful on size or use indexer instead.", false)]
        public abstract ref T UnsafeIndex(int column, int row);

        private protected void AssertIndex(int column, int row)
        {
            if (column < 0 || column >= ColumnCount) {
                throw new ArgumentOutOfRangeException(nameof(column));
            }

            if (row < 0 || row >= RowCount) {
                throw new ArgumentOutOfRangeException(nameof(row));
            }
        }

    }

    internal unsafe class GCMatrix<T> : Matrix<T> where T: unmanaged, INumber<T>
    {

        private readonly MatrixKernel[,] buffer;

        public GCMatrix(int column, int row)
        {
            KernelColumnCount = (column + 3) / 4;
            KernelRowCount = (row + 3) / t_count;
            buffer = new MatrixKernel[KernelColumnCount, KernelRowCount];
        }

        public override ref T this[int column, int row]
        {
            get
            {
                AssertIndex(column, row);
                int kernelColumn = column / 4, c = column % 4;
                int kernelRow = row / t_count, r = row % t_count;
                ref MatrixKernel kernel = ref buffer[kernelColumn, kernelRow];
                return ref kernel.UnsafeIndex<T>(c, r);
            }
        }

        public override Matrix<T> this[ReadOnlySpan<MatrixIndex> column, ReadOnlySpan<MatrixIndex> row]
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override unsafe ref MatrixKernel GetMatrixKernel(int column, int row)
        {
            AssertIndex(column, row);
            int kernelColumn = column / 4;
            int kernelRow = row / t_count;
            return ref buffer[kernelColumn, kernelRow];
        }

        public override ref T UnsafeIndex(int column, int row)
        {
            int kernelColumn = column / 4, c = column % 4;
            int kernelRow = row / t_count, r = row % t_count;
            ref MatrixKernel kernel = ref buffer[kernelColumn, kernelRow];
            return ref kernel.UnsafeIndex<T>(c, r);
        }

    }

    internal unsafe class HlsfMatrix<T> : Matrix<T> where T: unmanaged, INumber<T>
    {

        private readonly MatrixKernel* k_buffer;
        private readonly hlsfHandle handle;

        internal HlsfMatrix(int column, int row, hlsfAllocator allocator)
        {
            KernelColumnCount = (column + 3) / 4;
            KernelRowCount = (row + 3) / t_count;
            this.handle = allocator.Alloc((uint)(KernelColumnCount * KernelRowCount * sizeof(MatrixKernel)));
            k_buffer = (MatrixKernel*)handle.Pointer;
        }

        public override ref T this[int column, int row]
        {
            get
            {
                AssertIndex(column, row);
                int kernelColumn = column / 4, c = column % 4;
                int kernelRow = row / t_count, r = row % t_count;
                ref MatrixKernel kernel = ref k_buffer[(kernelColumn * kernelColumn) + kernelRow];
                return ref kernel.UnsafeIndex<T>(c, r);
            }
        }

        public override Matrix<T> this[ReadOnlySpan<MatrixIndex> column, ReadOnlySpan<MatrixIndex> row]
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override unsafe ref MatrixKernel GetMatrixKernel(int column, int row)
        {
            AssertIndex(column, row);
            int kernelColumn = column / 4, c = column % 4;
            int kernelRow = row / t_count, r = row % t_count;
            return ref k_buffer[(kernelColumn * kernelColumn) + kernelRow];
        }

        public override ref T UnsafeIndex(int column, int row)
        {
            int kernelColumn = column / 4, c = column % 4;
            int kernelRow = row / t_count, r = row % t_count;
            ref MatrixKernel kernel = ref k_buffer[(kernelColumn * kernelColumn) + kernelRow];
            return ref kernel.UnsafeIndex<T>(c, r);
        }

    }
}