DigitalData.Auth/src/DigitalData.Auth.API/Hubs/AuthHub.cs

using DigitalData.Auth.Abstractions;
using DigitalData.Core.Abstractions.Security;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Caching.Memory;

namespace DigitalData.Auth.API.Hubs;

public class AuthHub : Hub<IAuthListenHandler>, IAuthSenderHandler
{
    private readonly ICryptoFactory _cFactory;

    private readonly ILogger _logger;

    private readonly IMemoryCache _cache;

    private readonly static string CacheId = Guid.NewGuid().ToString();

    public AuthHub(ICryptoFactory cryptoFactory, ILogger<AuthHub> logger, IMemoryCache cache)
    {
        _cFactory = cryptoFactory;
        _logger = logger;
        _cache = cache;
    }

    public async Task GetPublicKeyAsync(string issuer, string audience)
    {
        if(_cFactory.TokenDescriptors.TryGet(issuer, audience, out var tDesc))
        {
            await Clients.Caller.ReceivePublicKeyAsync(issuer, audience, tDesc.PublicKey.Content);
        }
        else
        {
            await Clients.Caller.ReceivePublicKeyAsync(issuer, audience, string.Empty);

            // Log this warning only once per minute to avoid unnecessary repetition.
            _cache.GetOrCreate(CacheId + "LastLoggingDate", e =>
            {
                _logger.LogWarning("Token description is not found. Issuer: {issuer} Audience: {audience}", issuer, audience);
                e.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(1);
                return true;
            });
        }
    }

    public async Task SendPublicKeyAsync(string issuer, string audience, string value)
        => await Clients.All.ReceivePublicKeyAsync(issuer, audience, value);
}