using Microsoft.Extensions.Caching.Memory;

namespace Harmonia.Core.Caching;

public abstract class MemoryCache<TKey, TValue> : Cache<TKey, TValue> where TKey : notnull
{
    private readonly IMemoryCache _memoryCache;

    protected virtual long? SizeLimit => 2000000000;
    protected virtual double CompactionPercentage => 0.2;
    protected virtual TimeSpan SlidingExpiration => TimeSpan.FromSeconds(600);

    public MemoryCache()
    {
        MemoryCacheOptions memoryCacheOptions = new()
        {
            SizeLimit = SizeLimit,
            CompactionPercentage = CompactionPercentage
        };

        _memoryCache = new MemoryCache(memoryCacheOptions);
    }

    protected override TValue? TryGetValue(object key)
    {
        _memoryCache.TryGetValue(key, out TValue? value);

        return value;
    }

    protected override void AddToCache(object key, TValue entry)
    {
        long entrySize = GetEntrySize(entry);

        var cacheEntryOptions = new MemoryCacheEntryOptions()
            .SetSize(entrySize)
            .SetSlidingExpiration(SlidingExpiration);

        _memoryCache.Set(key, entry, cacheEntryOptions);
    }

    protected abstract long GetEntrySize(TValue entry);
}