namespace NATS.Server.LeafNodes;

public enum LeafMapDirection
{
    Inbound,
    Outbound,
}

public sealed record LeafMappingResult(string Account, string Subject);

public sealed class LeafHubSpokeMapper
{
    private readonly IReadOnlyDictionary<string, string> _hubToSpoke;
    private readonly IReadOnlyDictionary<string, string> _spokeToHub;

    public LeafHubSpokeMapper(IReadOnlyDictionary<string, string> hubToSpoke)
    {
        _hubToSpoke = hubToSpoke;
        _spokeToHub = hubToSpoke.ToDictionary(static p => p.Value, static p => p.Key, StringComparer.Ordinal);
    }

    public LeafMappingResult Map(string account, string subject, LeafMapDirection direction)
    {
        if (direction == LeafMapDirection.Outbound && _hubToSpoke.TryGetValue(account, out var spoke))
            return new LeafMappingResult(spoke, subject);
        if (direction == LeafMapDirection.Inbound && _spokeToHub.TryGetValue(account, out var hub))
            return new LeafMappingResult(hub, subject);
        return new LeafMappingResult(account, subject);
    }
}