// (c) Copyright Ascensio System SIA 2010-2022
//
// This program is a free software product.
// You can redistribute it and/or modify it under the terms
// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
// Foundation. In accordance with Section 7(a) of the GNU AGPL its Section 15 shall be amended
// to the effect that Ascensio System SIA expressly excludes the warranty of non-infringement of
// any third-party rights.
//
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// of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For details, see
// the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
//
// You can contact Ascensio System SIA at Lubanas st. 125a-25, Riga, Latvia, EU, LV-1021.
//
// The  interactive user interfaces in modified source and object code versions of the Program must
// display Appropriate Legal Notices, as required under Section 5 of the GNU AGPL version 3.
//
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// distributing the program. Pursuant to Section 7(e) we decline to grant you any rights under
// trademark law for use of our trademarks.
//
// All the Product's GUI elements, including illustrations and icon sets, as well as technical writing
// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode


namespace ASC.Common.Caching;

[Singletone]
public class RedisCacheNotify<T> : ICacheNotify<T> where T : IMessage<T>, new()
{
    private readonly IRedisDatabase _redis;
    private readonly ConcurrentDictionary<CacheNotifyAction, ConcurrentBag<Action<T>>> _invoctionList;
    private readonly Guid _instanceId;

    public RedisCacheNotify(IRedisClient redisCacheClient)
    {
        _redis = redisCacheClient.GetDefaultDatabase();
        _instanceId = Guid.NewGuid();
        _invoctionList = new ConcurrentDictionary<CacheNotifyAction, ConcurrentBag<Action<T>>>();
    }


    public void Publish(T obj, CacheNotifyAction action)
    {
        Task.Run(async () => await _redis.PublishAsync(GetChannelName(), new RedisCachePubSubItem<T>() { Id = _instanceId, Object = obj, Action = action }))
            .GetAwaiter()
            .GetResult();

        foreach (var hanlder in GetInvoctionList(action))
        {
            hanlder(obj);
        }
    }

    public async Task PublishAsync(T obj, CacheNotifyAction action)
    {
        await Task.Run(async () => await _redis.PublishAsync(GetChannelName(), new RedisCachePubSubItem<T>() { Id = _instanceId, Object = obj, Action = action }));

        foreach (var hanlder in GetInvoctionList(action))
        {
            hanlder(obj);
        }
    }

    public void Subscribe(Action<T> onChange, CacheNotifyAction action)
    {
        Task.Run(async () => await _redis.SubscribeAsync<RedisCachePubSubItem<T>>(GetChannelName(), (i) =>
        {
            if (i.Id != _instanceId && (i.Action == action || Enum.IsDefined(typeof(CacheNotifyAction), (i.Action & action))))
            {
                onChange(i.Object);
            }

            return Task.FromResult(true);
        })).GetAwaiter()
          .GetResult();

        AddToInInvoctionList(onChange, action);
    }

    public void Unsubscribe(CacheNotifyAction action)
    {
        Task.Run(async () => await _redis.UnsubscribeAsync<RedisCachePubSubItem<T>>(GetChannelName(), (i) =>
        {
            return Task.FromResult(true);
        })).GetAwaiter()
          .GetResult();

        _invoctionList.TryRemove(action, out _);
    }

    private string GetChannelName()
    {
        return $"asc:channel:{typeof(T).FullName}".ToLower(CultureInfo.InvariantCulture);
    }

    private List<Action<T>> GetInvoctionList(CacheNotifyAction action)
    {
        var result = new List<Action<T>>();

        foreach (var val in (CacheNotifyAction[])Enum.GetValues(typeof(CacheNotifyAction)))
        {
            if (!(val == action || Enum.IsDefined(typeof(CacheNotifyAction), (val & action)))) continue;

            if (_invoctionList.TryGetValue(val, out var handlers))
            {
                result.AddRange(handlers);
            }

        }

        return result;
    }

    private void AddToInInvoctionList(Action<T> onChange, CacheNotifyAction action)
    {
        if (onChange != null)
        {
            _invoctionList.AddOrUpdate(action,
                new ConcurrentBag<Action<T>> { onChange },
                (type, bag) =>
                {
                    bag.Add(onChange);
                    return bag;
                });
        }
        else
        {
            _invoctionList.TryRemove(action, out _);
        }
    }


    class RedisCachePubSubItem<T0>
    {
        public Guid Id { get; set; }

        public T0 Object { get; set; }

        public CacheNotifyAction Action { get; set; }
    }
}