//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="MatrixParallel"
// Project: StgSharp
// AuthorGroup: Nitload
// Copyright (c) Nitload. All rights reserved.
//     
// 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
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//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using StgSharp.Collections;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace StgSharp.Mathematics.Numeric
{
    public static unsafe partial class MatrixParallel
    {

        private static bool _meaningful;

        private static CapacityFixedStack<MatrixParallelThread> _threads;

        public static bool IsParallelSupported { get; } = Environment.ProcessorCount > 6;

        public static bool IsParallelMeaningful { get; } = (Environment.ProcessorCount > 6) &&
                                                           IsInitialized;

        public static int ContextCount { get; private set; }

        private static bool IsInitialized { get; set; }

        internal static void Init()
        {
            Dictionary<SIMDID, int> contextMap = [];

            if (IsInitialized) {
                return;
            }
            if (!IsParallelSupported)
            {
                IsInitialized = true;
                return;
            }
            contextMap = [];
            int count = Environment.ProcessorCount;
            _threads = new(count);
            for (int i = 0; i < count; i++)
            {
                MatrixParallelThread thread = new(i);
                _threads.Push(thread);
                SpinWait.SpinUntil(() => thread.State == MatrixThreadState.Ready);
            }

            // TODO 构建全局的保底上下文
            foreach (MatrixParallelThread thread in _threads) { }
            if (contextMap.Keys.Count == 1)
            {
                for (int i = 0; i < 4; i++)
                {
                    MatrixParallelThread thread = _threads.Pop();
                    thread.Dispose();
                }
            } else
            {
                // TODO 排序并丢弃四个能力最弱线程
            }
            _awaitingLeaderHandle = new AwaitingQueue();
            IsInitialized = true;
        }

        [LibraryImport(Native.LibName, EntryPoint = "sn_compare_simd")]
        [UnmanagedCallConv(CallConvs = [ typeof(CallConvCdecl) ])]
        private static unsafe partial ulong CompareSIMDID(
                                            IntrinsicContext* context,
                                            ulong id
        );

    }
}