using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;

namespace iGP
{

    public class ThreadManager
    {
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        //Public nested data structures declaration
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        public delegate void ThreadCall( object data, Action onResult );

        private struct ThreadParams
        {
            public ThreadCall threadCall;
            public object data;
            public Action onResult;

            public ThreadParams( ThreadCall threadCall, object data, Action onResult )
            {
                this.threadCall = threadCall;
                this.data = data;
                this.onResult = onResult;
            }
        }

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        //Public methods
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        public static void CalledOnUnityMainThread()
        {
            while (onResultQueue.Count > 0)
            {
                onResultQueue.Dequeue().Invoke();
            }
        }

        public void Run( ThreadCall threadCall, object data, Action onResult )
        {
            var thread = new Thread(ThreadFunction);
            ThreadParams threadParams = new ThreadParams(threadCall, data, onResult);
            thread.Start(threadParams);
            thread.IsBackground = true;
        }

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        //Private methods
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        private static void ThreadFunction( object state )
        {
            ThreadParams threadParams;
            try
            {
                threadParams = (ThreadParams) state;
            }
            catch
            {
                return;
            }

            threadParams.threadCall( threadParams.data, threadParams.onResult );

            lock(lockObj)
            {
                onResultQueue.Enqueue(threadParams.onResult);
            }
        }

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        //Private fields
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        private static Queue<Action> onResultQueue = new Queue<Action>();
        private static System.Object lockObj = new System.Object();
    }
}