using Microsoft.Extensions.Caching.Memory;

namespace YLErp.Helpers
{
    /// <summary>
    /// 多线程并发锁帮助类
    /// </summary>
    public static class LockHelper
    {
        /// <summary>
        /// 获取用于现成锁定的对象,解决前端的并发请求问题
        /// </summary>
        /// <param name="keyId">唯一标识ID,建议格式为:功能ID+数据ID</param>
        /// <param name="lockSeconds">对象锁定时间,仅在第一次锁定时使用,锁定时间过期后对象被释放</param>
        public static object Acquire(string keyId, int lockSeconds = 60)
        {
            if (string.IsNullOrEmpty(keyId))
            {
                throw new ArgumentException($"“{nameof(keyId)}”不能是 Null 或为空", nameof(keyId));
            }

            lock (InnerHelper.MemoryCache)
            {
                var obj = InnerHelper.MemoryCache.Get(keyId);

                if (obj == null)
                {
                    var cacheEntryOptions = new MemoryCacheEntryOptions().SetSlidingExpiration(TimeSpan.FromSeconds(lockSeconds));
                    InnerHelper.MemoryCache.Set(keyId, obj = new object(), cacheEntryOptions);
                }

                return obj;
            }
        }

        /// <summary>
        /// 获取用于现成锁定的对象,解决前端的并发请求问题
        /// </summary>
        /// <param name="keyId">唯一标识ID,建议格式为:功能ID+数据ID</param>
        /// <param name="instanceHandler">锁定实例处理器</param>
        /// <param name="lockSeconds">对象锁定时间,仅在第一次锁定时使用,锁定时间过期后对象被释放</param>
        public static T Acquire<T>(string keyId, ILockInstanceHandler<T> instanceHandler, int lockSeconds = 60) where T : class
        {
            if (string.IsNullOrEmpty(keyId))
            {
                throw new ArgumentException($"“{nameof(keyId)}”不能是 Null 或为空", nameof(keyId));
            }

            if (instanceHandler is null)
            {
                throw new ArgumentNullException(nameof(instanceHandler));
            }

            lock (InnerHelper.MemoryCache)
            {
                var obj = InnerHelper.MemoryCache.Get(keyId);

                if (obj == null)
                {
                    var cacheEntryOptions = new MemoryCacheEntryOptions().SetSlidingExpiration(TimeSpan.FromSeconds(lockSeconds));

                    InnerHelper.MemoryCache.Set(keyId, obj = instanceHandler.Create(), cacheEntryOptions);
                }
                else
                {
                    instanceHandler.Update((T)obj);
                }

                return (T)obj;
            }
        }
        public static void Release(string keyId)
        {
            if (string.IsNullOrEmpty(keyId))
            {
                return;
            }

            lock (InnerHelper.MemoryCache)
            {
                InnerHelper.MemoryCache.Remove(keyId);
            }
        }
    }

    /// <summary>
    /// 锁定实例处理
    /// </summary>
    public interface ILockInstanceHandler<T> where T : class
    {
        /// <summary>
        /// 创建新的锁定实例(如果缓存中不存在的话)
        /// </summary>
        T Create();

        /// <summary>
        /// 更新锁定实例(如果缓存中存在的话)
        /// </summary>
        void Update(T instance);
    }
}