using Microsoft.Extensions.Logging.Abstractions;
using ZB.MOM.WW.ScadaBridge.HealthMonitoring;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;

namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests.Scripts;

/// <summary>
/// SiteRuntime-S2/UA5: the hosted reporter must lift the process-wide
/// <see cref="ScriptExecutionScheduler"/> gauges onto the site health report via
/// <see cref="ISiteHealthCollector"/>. Uses the real collector (NSubstitute is not
/// referenced by this test project) and drives the shared scheduler busy so the
/// pushed value is distinguishable from the idle default.
/// </summary>
public class ScriptSchedulerStatsReporterTests
{
    [Fact]
    public async Task Reporter_PushesSchedulerStatsToCollector()
    {
        var options = new SiteRuntimeOptions { ScriptExecutionThreadCount = 1 };
        var collector = new SiteHealthCollector();
        var scheduler = ScriptExecutionScheduler.Shared(options);

        using var gate = new ManualResetEventSlim(false);
        // Occupy a worker thread so BusyThreadCount is a non-zero, distinguishable value.
        var blocking = Task.Factory.StartNew(() => gate.Wait(),
            CancellationToken.None, TaskCreationOptions.None, scheduler);
        await WaitUntilAsync(() => scheduler.BusyThreadCount >= 1);

        using var reporter = new ScriptSchedulerStatsReporter(
            collector, options, NullLogger<ScriptSchedulerStatsReporter>.Instance,
            pollInterval: TimeSpan.FromMilliseconds(50));

        await reporter.StartAsync(CancellationToken.None);
        try
        {
            await WaitUntilAsync(() => collector.CollectReport("site-1").ScriptBusyThreads >= 1);
            var report = collector.CollectReport("site-1");
            Assert.True(report.ScriptBusyThreads >= 1);
            Assert.NotNull(report.ScriptOldestBusyAgeSeconds); // a script is in flight
        }
        finally
        {
            gate.Set();
            await blocking;
            await reporter.StopAsync(CancellationToken.None);
        }
    }

    private static async Task WaitUntilAsync(Func<bool> condition)
    {
        for (var i = 0; i < 100 && !condition(); i++)
            await Task.Delay(50);
        Assert.True(condition(), "condition not met within timeout");
    }
}