using Microsoft.AspNetCore.Server.Kestrel.Core;
using ZB.MOM.WW.ScadaBridge.Host;

namespace ZB.MOM.WW.ScadaBridge.Host.Tests;

/// <summary>
/// The site node's Kestrel configuration, asserted against the code that actually ships (the other
/// Host startup tests re-declare their own <c>ConfigureKestrel</c> lambda, which can never catch a
/// regression in <c>Program.cs</c>'s).
/// </summary>
public class SiteKestrelSetupTests
{
    [Fact]
    public void SiteListener_EnablesHttp2Keepalive()
    {
        // Arch-review 2026-08-19 P4-3. Kestrel's default KeepAlivePingDelay is TimeSpan.MaxValue —
        // no server-initiated pings — so a half-open HTTP/2 connection is never detected on a
        // stream that is legitimately silent. The LocalDb sync stream is exactly that: with the
        // dialling node crashed or partitioned, this node's handler stays parked on a dead stream
        // holding the single-stream guard, refusing the reconnect that would heal the pair.
        var options = new KestrelServerOptions();

        SiteKestrelSetup.Configure(options, grpcPort: 8083, metricsPort: 8084);

        Assert.NotEqual(TimeSpan.MaxValue, options.Limits.Http2.KeepAlivePingDelay);
        Assert.Equal(SiteKestrelSetup.Http2KeepAlivePingDelay, options.Limits.Http2.KeepAlivePingDelay);
        Assert.Equal(SiteKestrelSetup.Http2KeepAlivePingTimeout, options.Limits.Http2.KeepAlivePingTimeout);
        // Detection has to be quick enough to matter, and a ping must not be its own timeout.
        Assert.True(SiteKestrelSetup.Http2KeepAlivePingTimeout < SiteKestrelSetup.Http2KeepAlivePingDelay);
        Assert.True(
            SiteKestrelSetup.Http2KeepAlivePingDelay + SiteKestrelSetup.Http2KeepAlivePingTimeout
                <= TimeSpan.FromMinutes(2));
    }

    [Fact]
    public void SiteListener_KeepsGrpcHttp2Only_AndMetricsHttp1Capable()
    {
        // The keepalive change must not disturb the protocol split: h2c-only on the gRPC port so
        // Grpc.AspNetCore can serve it without TLS ALPN, HTTP/1.1-capable on the metrics port so a
        // standard Prometheus scraper can reach /metrics.
        var options = new KestrelServerOptions();

        SiteKestrelSetup.Configure(options, grpcPort: 8083, metricsPort: 8084);

        var endpoints = options.GetType()
            .GetProperty("CodeBackedListenOptions", System.Reflection.BindingFlags.Instance
                | System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Public)!
            .GetValue(options) as System.Collections.IEnumerable;
        Assert.NotNull(endpoints);

        var protocols = endpoints!.Cast<ListenOptions>().Select(o => o.Protocols).ToList();
        Assert.Equal(2, protocols.Count);
        Assert.Equal(HttpProtocols.Http2, protocols[0]);
        Assert.Equal(HttpProtocols.Http1AndHttp2, protocols[1]);
    }
}