namespace Salmon.Core.Depth;

public abstract class Persistence
{
    /// <summary>
    /// Must be thread safe
    /// Must return immediately
    /// </summary>
    /// <param name="key">May not be null</param>
    /// <param name="value"></param>
    public virtual void PushStateChange(string subject, string predicate, object? value, DateTime when)
    {
        Task.Run(async () =>
        {
            try
            {
                var old = await GetLastValue(subject, predicate);
                if(old != value)

                await RegisterStateChange(subject, predicate, when, value);
            }catch (Exception ex)
            {
                ExceptionCatched(ex);
            }
        }).ConfigureAwait(false);
    }

    public abstract Task<object> GetLastValue(string subject, string predicate);

    protected abstract Task RegisterStateChange(string subject, string predicate, DateTime when, object? value);
    protected virtual void ExceptionCatched(Exception e)
    {
        Console.WriteLine(e.ToString());
    }
}