using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using StellaOps.Scanner.WebService.Services;

namespace StellaOps.Scanner.WebService.Endpoints;

internal static class ObservabilityEndpoints
{
    public static void MapObservabilityEndpoints(this IEndpointRouteBuilder endpoints)
    {
        ArgumentNullException.ThrowIfNull(endpoints);

        endpoints.MapGet("/metrics", HandleMetricsAsync)
            .WithName("scanner.metrics")
            .WithDescription("Exposes scanner service metrics in Prometheus text format (text/plain 0.0.4). Scraped by Prometheus without authentication.")
            .Produces(StatusCodes.Status200OK)
            .AllowAnonymous();
    }

    private static IResult HandleMetricsAsync(OfflineKitMetricsStore metricsStore)
    {
        ArgumentNullException.ThrowIfNull(metricsStore);

        var payload = metricsStore.RenderPrometheus();
        return Results.Text(payload, contentType: "text/plain; version=0.0.4; charset=utf-8");
    }
}