harmonia/Harmonia.Core/Caching/Cache.cs

namespace Harmonia.Core.Caching;

public abstract class Cache<TKey, TValue> : ICache<TKey, TValue> where TKey : notnull
{
    protected abstract TValue? TryGetValue(object key);
    protected abstract TValue? Fetch(TKey key);
    protected abstract void AddToCache(object key, TValue value);

    public TValue? Get(TKey key)
    {
        object? actualKey = GetKey(key);

        if (actualKey == null)
            return default;

        return TryGetValue(actualKey) ?? Refresh(key);
    }

    public TValue? Refresh(TKey key)
    {
        object? actualKey = GetKey(key);

        if (actualKey == null)
            return default;

        TValue? value = Fetch(key);

        if (value == null)
            return default;

        AddToCache(actualKey, value);

        return value;
    }

    protected virtual object? GetKey(TKey key)
    {
        return key;
    }
}