using SmartCoalApplication.SystemLayer;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace SmartCoalApplication.Core.Threading
{
    public class WaitableCounter
    {
        public static int MinimumCount
        {
            get
            {
                return WaitHandleArray.MinimumCount;
            }
        }

        public static int MaximumCount
        {
            get
            {
                return WaitHandleArray.MaximumCount;
            }
        }

        private sealed class CounterToken
            : IDisposable
        {
            private WaitableCounter parent;
            private int index;

            public int Index
            {
                get
                {
                    return this.index;
                }
            }

            public CounterToken(WaitableCounter parent, int index)
            {
                this.parent = parent;
                this.index = index;
            }

            public void Dispose()
            {
                parent.Release(this);
            }
        }

        private WaitHandleArray freeEvents;
        private WaitHandleArray inUseEvents;

        private object theLock;

        public WaitableCounter(int maxCount)
        {
            if (maxCount < 1 || maxCount > 64)
            {
                throw new ArgumentOutOfRangeException("maxCount", "must be between 1 and 64, inclusive");
            }

            this.freeEvents = new WaitHandleArray(maxCount);
            this.inUseEvents = new WaitHandleArray(maxCount);

            for (int i = 0; i < maxCount; ++i)
            {
                this.freeEvents[i] = new ManualResetEvent(true);
                this.inUseEvents[i] = new ManualResetEvent(false);
            }

            this.theLock = new object();
        }

        private void Release(CounterToken token)
        {
            ((ManualResetEvent)this.inUseEvents[token.Index]).Reset();
            ((ManualResetEvent)this.freeEvents[token.Index]).Set();
        }

        public IDisposable AcquireToken()
        {
            lock (this.theLock)
            {
                int index = WaitForNotFull();
                ((ManualResetEvent)this.freeEvents[index]).Reset();
                ((ManualResetEvent)this.inUseEvents[index]).Set();
                return new CounterToken(this, index);
            }
        }

        public bool IsEmpty()
        {
            return IsEmpty(0);
        }

        public bool IsEmpty(uint msTimeout)
        {
            return freeEvents.AreAllSignaled(msTimeout);
        }

        public void WaitForEmpty()
        {
            freeEvents.WaitAll();
        }

        public int WaitForNotFull()
        {
            int returnVal = freeEvents.WaitAny();
            return returnVal;
        }

    }
}