using System.Net;
using Microsoft.AspNetCore.Mvc.Testing;

namespace Bff.Tests;

/// <summary>
/// S-16c (#124): the service exposes OTel HTTP-server metrics in Prometheus text format at /metrics,
/// so Prometheus can scrape the golden signals (traffic, errors, latency) for the request path.
/// </summary>
public class MetricsEndpointTests(WebApplicationFactory<Program> factory)
    : IClassFixture<WebApplicationFactory<Program>>
{
    [Fact]
    public async Task Metrics_endpoint_exposes_http_server_request_duration_after_traffic()
    {
        var client = factory.CreateClient();

        // One request produces an http.server.request.duration measurement...
        await client.GetAsync("/health");

        // ...which the /metrics scrape endpoint then exposes in Prometheus text format.
        var response = await client.GetAsync("/metrics");

        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        var body = await response.Content.ReadAsStringAsync();
        Assert.Contains("http_server_request_duration", body);
    }
}