/*************************************************************************
 *  Copyright © 2018-2023 Liwen All rights reserved.
 *------------------------------------------------------------------------
 *  File         :  PagedLodThreadPool.cs
 *  Description  :  Load tile file with threadpool
 *------------------------------------------------------------------------
 *  Author       :  Liwen
 *  Version      :  1.0.0
 *  Date         :  1/5/2019
 *  Description  :  Initial development version.
 *************************************************************************/

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;
using System.Threading;
using System.Linq;
namespace AIPagedLod
{
    public class PagedLodThreadPool : MonoBehaviour
    {
        static PagedLodThreadPool mCurrentPoll;
        static int mNumThreads;
        List<Action> mCurrentActions = new List<Action>();
        List<Action> mActions = new List<Action>();
        void Start()
        {
            mCurrentPoll = this;
            ThreadPool.SetMaxThreads(PagedLodConfig.mThreadCount, PagedLodConfig.mThreadCount);
        }


        public static void QueueOnMainThread(Action action)
        {
            lock (mCurrentPoll.mActions)
            {
                mCurrentPoll.mActions.Add(action);
            }
        }

        public static bool IsQueueWorkItem()
        {
            if (!PagedLodUpdateController.IsUpdateEnabled())
            {
                return false;
                //return mNumThreads < 1;
            }
            return mNumThreads < PagedLodConfig.mThreadCount;
        }

        public static Thread RunAsync(Action a)
        {
            ThreadPool.QueueUserWorkItem(RunAction, a);
            Interlocked.Increment(ref mNumThreads);
            return null;
        }

        private static void RunAction(object action)
        {
            try
            {
                ((Action)action)();
            }
            catch
            {
            }
            finally
            {
                Interlocked.Decrement(ref mNumThreads);
            }

        }

        void OnDisable()
        {
            if (mCurrentPoll == this)
            {
                mCurrentPoll = null;
            }
        }

        void Update()
        {
            lock (mActions)
            {
                mCurrentActions.Clear();
                mCurrentActions.AddRange(mActions);
                mActions.Clear();
            }
            for (int i = 0; i < mCurrentActions.Count; ++i)
            {
                mCurrentActions[i]();
            }     
        }
    }
}