using System.Collections.Concurrent;
using System.Threading;

namespace SKMC.Api.Common.Types
{
    /// <summary>
    /// 阻塞队列
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class BlockingQueue<T>
    {
        private readonly ConcurrentQueue<T> queue;

        private readonly ManualResetEvent manualResetEvent;

        public BlockingQueue()
        {
            queue = new ConcurrentQueue<T>();
            manualResetEvent = new ManualResetEvent(false);
        }

        public int Count { get => queue.Count; }

        public void Add(T item)
        {
            queue.Enqueue(item);
            manualResetEvent.Set();
        }

        public T Take()
        {
            bool isEmpty = false;
            T item = default(T);
            while (true)
            {
                if (queue.Count > 0)
                {
                    queue.TryDequeue(out item);
                    manualResetEvent.Reset();
                }
                else
                {
                    isEmpty = true;
                }
                if (item != null) return item;
                if (isEmpty) manualResetEvent.WaitOne();
            }
        }

        public void Stop() => manualResetEvent.Set();
    }
}