using System.Collections.Concurrent;
using System.Net;

namespace PrivaPub.Infrastructure.Http
{
	public interface IConnectedAddresses
	{
		void Remember(string host, IPAddress address);
		IPAddress Of(string host);
	}

	public class ConnectedAddresses : IConnectedAddresses
	{
		const int MaxHosts = 50_000;

		readonly ConcurrentDictionary<string, IPAddress> _addresses = new(StringComparer.OrdinalIgnoreCase);

		public void Remember(string host, IPAddress address)
		{
			if (string.IsNullOrEmpty(host) || address == default)
				return;
			if (_addresses.Count >= MaxHosts)
				_addresses.Clear();
			_addresses[host] = address.IsIPv4MappedToIPv6 ? address.MapToIPv4() : address;
		}

		public IPAddress Of(string host) => host != default && _addresses.TryGetValue(host, out var address) ? address : default;
	}
}