using NATS.Server.JetStream.Models;

namespace NATS.Server.JetStream.Validation;

public static class JetStreamConfigValidator
{
    public static ValidationResult Validate(StreamConfig config)
    {
        if (string.IsNullOrWhiteSpace(config.Name) || config.Subjects.Count == 0)
            return ValidationResult.Invalid("name/subjects required");

        if (config.Retention == RetentionPolicy.WorkQueue && config.MaxConsumers == 0)
            return ValidationResult.Invalid("workqueue retention requires max consumers > 0");
        if (config.MaxMsgSize < 0)
            return ValidationResult.Invalid("max_msg_size must be >= 0");
        if (config.MaxMsgsPer < 0)
            return ValidationResult.Invalid("max_msgs_per must be >= 0");
        if (config.MaxAgeMs < 0)
            return ValidationResult.Invalid("max_age_ms must be >= 0");

        return ValidationResult.Valid();
    }
}

public sealed class ValidationResult
{
    public bool IsValid { get; }
    public string Message { get; }

    private ValidationResult(bool isValid, string message)
    {
        IsValid = isValid;
        Message = message;
    }

    public static ValidationResult Valid() => new(true, string.Empty);
    public static ValidationResult Invalid(string message) => new(false, message);
}