using Core.Blueprint.Caching.Contracts;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Caching.Memory;
using System.Text.Json;

namespace Core.Blueprint.Caching
{
    public sealed class MemoryCacheProvider : ICacheProvider
    {
        private readonly IMemoryCache _cache;
        private readonly ILogger<MemoryCacheProvider> _logger;
        public MemoryCacheProvider(IMemoryCache cache, ILogger<MemoryCacheProvider> logger)
        {
            _cache = cache;
            _logger = logger;
        }

        public ValueTask<TEntity> GetAsync<TEntity>(string key)
        {
            if (_cache.TryGetValue(key, out var value))
            {
                if (value is TEntity typedValue)
                {
                    return ValueTask.FromResult(typedValue);
                }

                try
                {
                    var json = value?.ToString();
                    var deserialized = JsonSerializer.Deserialize<TEntity>(json);
                    return ValueTask.FromResult(deserialized);
                }
                catch (Exception ex)
                {
                    _logger.LogWarning(ex, "Error deserializing cache value for key {Key}", key);
                }
            }

            return ValueTask.FromResult(default(TEntity));
        }

        public ValueTask SetAsync<TEntity>(string key, TEntity value, TimeSpan? expiry = null)
        {
            var options = new MemoryCacheEntryOptions();
            if (expiry.HasValue)
            {
                options.SetAbsoluteExpiration(expiry.Value);
            }

            _cache.Set(key, value, options);
            return ValueTask.CompletedTask;
        }

        public ValueTask RemoveAsync(string key)
        {
            _cache.Remove(key);
            return ValueTask.CompletedTask;
        }

        public ValueTask<bool> ExistsAsync(string key)
        {
            return ValueTask.FromResult(_cache.TryGetValue(key, out _));
        }

        public ValueTask RefreshAsync(string key, TimeSpan? expiry = null)
        {
            // MemoryCache does not support sliding expiration refresh like Redis,
            // so we must re-set the value manually if required.

            if (_cache.TryGetValue(key, out var value))
            {
                _cache.Remove(key);

                var options = new MemoryCacheEntryOptions();
                if (expiry.HasValue)
                {
                    options.SetAbsoluteExpiration(expiry.Value);
                }

                _cache.Set(key, value, options);
            }

            return ValueTask.CompletedTask;
        }
    }
}