using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;

/// <summary>
///     Review 2026-10-21 R06:O-4 — <c>ProbeTimeoutSeconds</c> was authored by the AdminUI and parsed, but consumed
///     by nothing: the Test Connect probe ran on the caller's budget alone. It now caps the probe deadline (it can
///     shorten the caller's budget, never extend it) — the same rule as the Galaxy probe.
/// </summary>
[Trait("Category", "Unit")]
public sealed class OpcUaClientProbeTimeoutTests
{
    /// <summary>The effective deadline is the shorter of the caller's budget and the configured cap.</summary>
    [Theory]
    [InlineData(10, 30, 10)]   // caller shorter → caller wins
    [InlineData(10, 2, 2)]     // config shorter → config caps
    [InlineData(10, 0, 10)]    // unset config → caller
    [InlineData(10, -1, 10)]   // nonsense config → caller
    [InlineData(0, 5, 1)]      // no caller budget → 1 s floor beats a longer config
    public void EffectiveTimeout_is_the_shorter_of_caller_and_config(int callerSeconds, int configSeconds, int expectedSeconds)
        => OpcUaClientDriverProbe.EffectiveTimeout(TimeSpan.FromSeconds(callerSeconds), configSeconds)
            .ShouldBe(TimeSpan.FromSeconds(expectedSeconds));

    /// <summary>
    ///     Against a port that accepts TCP but never speaks OPC UA, a 1 s configured cap returns long before the
    ///     caller's 30 s budget — the discovery handshake does the waiting, so this exercises the real deadline path.
    /// </summary>
    [Fact]
    public async Task Configured_cap_shortens_the_probe_against_a_silent_listener()
    {
        var listener = new TcpListener(IPAddress.Loopback, 0);
        listener.Start();
        try
        {
            var port = ((IPEndPoint)listener.LocalEndpoint).Port;
            var config = $$"""{ "endpointUrl": "opc.tcp://127.0.0.1:{{port}}", "probeTimeoutSeconds": 1 }""";

            var sw = Stopwatch.StartNew();
            var result = await new OpcUaClientDriverProbe().ProbeAsync(config, TimeSpan.FromSeconds(30), TestContext.Current.CancellationToken);
            sw.Stop();

            result.Ok.ShouldBeFalse();
            sw.Elapsed.ShouldBeLessThan(TimeSpan.FromSeconds(15), $"the 1 s configured cap must bound the probe (message: {result.Message})");
        }
        finally
        {
            listener.Stop();
        }
    }
}