using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TokenBucketLib
{
    /// <summary>
    /// 队列令牌桶
    /// 资源请求首先到达令牌桶，如果获得令牌马上返回，如果失败将进入等待队列，等待获得令牌后返回，或者令牌桶满后获取失败并丢弃。
    /// </summary>
    public class QueueTokenBucket : TokenBucket
    {
        /// <summary>
        /// 最大缓冲对列数。-1为不限长度。
        /// </summary>
        public int QueueMaxLenth { get; set; }

        private Queue<TokenBucketPass> queue;
        private readonly static object objlock = new object();

        /// <summary>
        /// 构造一个带缓冲队列的令牌桶
        /// </summary>
        public QueueTokenBucket()
            : this(-1)
        {
        }

        /// <summary>
        /// 通过提供最大缓冲队列数构造缓冲队列令牌桶
        /// </summary>
        /// <param name="queueMaxLenth">缓冲区大小。-1为不限制大小。</param>
        public QueueTokenBucket(int queueMaxLenth)
        {
            QueueMaxLenth = queueMaxLenth;
            queue = new Queue<TokenBucketPass>();
            base.Put += new Action<TokenBucket>(QueueTokenBuket_Put);
        }

        private void QueueTokenBuket_Put(TokenBucket obj)
        {
            if (queue.Count > 0)
            {
                lock (objlock)
                {
                    var c = queue.Count;
                    for (int i = 0; i < c; i++)
                    {
                        var r = base.GetToken();
                        if (r.State == TokenBucketPassEnum.passed)
                        {
                            TokenBucketPass result = queue.Dequeue();
                            result.State = TokenBucketPassEnum.passed;
                            if (GetTokenEnd != null) GetTokenEnd(this, new TokenBucketEventArgs(result));
                        }
                        else
                        {
                            break;
                        }
                    }
                }
            }
        }

        /// <summary>
        /// 
        /// </summary>
        public event Action<QueueTokenBucket, TokenBucketEventArgs> GetTokenEnd;

        /// <summary>
        /// 开始异步获取令牌
        /// </summary>
        /// <param name="requester">异步传入的对象，这个对象会随TokenBucketPass.Requester传出。</param>
        public void GetTokenAsyn(object requester)
        {
            var result = new TokenBucketPass();
            result.Requester = requester;
            var r = base.GetToken();
            if (r.State == TokenBucketPassEnum.passed)
            {
                result.State = r.State;
                if (GetTokenEnd != null) GetTokenEnd(this, new TokenBucketEventArgs(result));
            }
            else
            {
                if (QueueMaxLenth != -1 && QueueMaxLenth < queue.Count)
                {
                    result.State = TokenBucketPassEnum.losted;
                    GetTokenEnd(this, new TokenBucketEventArgs(result));
                }
                else
                {
                    queue.Enqueue(result);
                }
            }
        }

        #region IDisposable 成员

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                queue.Clear();
            }
            base.Dispose(disposing);
        }
        #endregion

    }
}