using Serilog.Events;
using ZB.MOM.WW.Configuration;

namespace ZB.MOM.WW.ScadaBridge.Host;

/// <summary>
/// Validates <see cref="LoggingOptions"/> at host startup (arch-review 08 round
/// 2 NF4). <see cref="LoggingOptions.MinimumLevel"/> is parsed into a Serilog
/// <see cref="LogEventLevel"/> by <c>LoggerConfigurationFactory.ParseLevel</c>,
/// which silently falls back to <c>Information</c> for an unrecognised value.
/// This validator surfaces that misconfiguration at boot instead: a present,
/// non-blank value must name a real level (Verbose/Debug/Information/Warning/
/// Error/Fatal, case-insensitive). A null/blank value is treated as "unset"
/// (defaults to Information), mirroring the parser.
/// </summary>
public sealed class LoggingOptionsValidator : OptionsValidatorBase<LoggingOptions>
{
    /// <inheritdoc />
    protected override void Validate(ValidationBuilder builder, LoggingOptions options)
    {
        builder.RequireThat(
            string.IsNullOrWhiteSpace(options.MinimumLevel)
                || Enum.TryParse<LogEventLevel>(options.MinimumLevel, ignoreCase: true, out _),
            $"ScadaBridge:Logging:{nameof(LoggingOptions.MinimumLevel)} ('{options.MinimumLevel}') " +
            $"is not a recognised Serilog level. Valid: {string.Join(", ", Enum.GetNames<LogEventLevel>())}.");
    }
}