using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using ZB.MOM.WW.LocalDb.Replication;
using ZB.MOM.WW.ScadaBridge.HealthMonitoring;
using ZB.MOM.WW.ScadaBridge.Host.Actors;

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

/// <summary>
/// Deferred-work register row 80 — a site node with replication UNCONFIGURED must report
/// <c>LocalDbReplicationConnected</c> and <c>LocalDbOplogBacklog</c> as <c>null</c>.
/// </summary>
/// <remarks>
/// <para>
/// The sibling <see cref="SiteLocalDbWiringTests"/> fixture is a <em>replicating</em> node
/// (it sets <c>LocalDb:Replication:ApiKey</c>, modelling the passive half of the rig's
/// site-a pair), so false/0 is the right answer there. This fixture is the other posture —
/// the rig's site-b/site-c, and the shipping default — with NEITHER <c>PeerAddress</c> nor
/// <c>ApiKey</c>.
/// </para>
/// <para>
/// The replication engine is registered unconditionally and idles, so <c>ISyncStatus</c>
/// still answers <c>Connected=false</c> with a real <c>0</c> backlog. Publishing that pair
/// is the row-80 bug: a dashboard reader sees <c>connected: false</c> on a perfectly healthy
/// unreplicated site and reads a fault, and central's null branches — the conditional KPI
/// emission and the sustained-badge anchor exclusion built for register row 33 — never
/// receive the null they exist for, so unreplicated sites emitted a misleading
/// <c>localDbReplicationConnected=0</c> series.
/// </para>
/// <para>
/// Built from the REAL composition root for the same reason the sibling fixture is: the
/// defect is in the wiring, and a hand-assembled <c>ServiceCollection</c> would prove
/// nothing about what the Host actually passes.
/// </para>
/// </remarks>
public class UnreplicatedSiteLocalDbHealthTests : IDisposable
{
    private readonly WebApplication _host;
    private readonly string _tempDbPath;
    private readonly string _tempSiteDbPath;
    private readonly string _tempTrackingDbPath;

    public UnreplicatedSiteLocalDbHealthTests()
    {
        var stamp = Guid.NewGuid();
        _tempDbPath = Path.Combine(Path.GetTempPath(), $"scadabridge_unrep_localdb_{stamp}.db");
        _tempSiteDbPath = Path.Combine(Path.GetTempPath(), $"scadabridge_unrep_site_{stamp}.db");
        _tempTrackingDbPath = Path.Combine(Path.GetTempPath(), $"scadabridge_unrep_track_{stamp}.db");

        var builder = WebApplication.CreateBuilder();
        builder.Configuration.Sources.Clear();
        builder.Configuration.AddInMemoryCollection(new Dictionary<string, string?>
        {
            ["ScadaBridge:Node:Role"] = "Site",
            ["ScadaBridge:Node:NodeName"] = "node-a",
            ["ScadaBridge:Node:NodeHostname"] = "test-site-b",
            ["ScadaBridge:Node:SiteId"] = "TestSiteB",
            ["ScadaBridge:Node:RemotingPort"] = "0",
            ["ScadaBridge:Node:GrpcPort"] = "0",
            ["ScadaBridge:Database:SiteDbPath"] = _tempSiteDbPath,
            ["ScadaBridge:OperationTracking:ConnectionString"] = $"Data Source={_tempTrackingDbPath}",
            ["ScadaBridge:Cluster:SeedNodes:0"] = "akka.tcp://scadabridge@localhost:2551",
            ["ScadaBridge:Cluster:SeedNodes:1"] = "akka.tcp://scadabridge@localhost:2552",

            // The point of this fixture: LocalDb:Path only. No PeerAddress, no ApiKey —
            // SiteLocalDbSetup.ReplicationIsConfigured is false, matching rig site-b/site-c.
            ["LocalDb:Path"] = _tempDbPath,
        });

        builder.Services.AddGrpc();
        builder.Services.AddSingleton<ZB.MOM.WW.ScadaBridge.Communication.Grpc.SiteStreamGrpcServer>();

        SiteServiceRegistration.Configure(builder.Services, builder.Configuration);

        AkkaHostedServiceRemover.RemoveAkkaHostedServiceOnly(builder.Services);

        _host = builder.Build();
    }

    public void Dispose()
    {
        (_host as IDisposable)?.Dispose();
        foreach (var path in new[] { _tempDbPath, _tempSiteDbPath, _tempTrackingDbPath })
        {
            try { File.Delete(path); } catch { /* best effort */ }
        }

        GC.SuppressFinalize(this);
    }

    [Fact]
    public void UnreplicatedSite_HealthReport_ReportsNullForBothLocalDbFields()
    {
        // The row-80 regression, end-to-end through the real container and the real
        // collector. Before the fix this produced false/0.
        var reporter = _host.Services.GetServices<IHostedService>()
            .OfType<LocalDbReplicationStatusReporter>()
            .Single();
        var collector = _host.Services.GetRequiredService<ISiteHealthCollector>();

        reporter.Probe();
        var report = collector.CollectReport("TestSiteB");

        Assert.Null(report.LocalDbReplicationConnected);
        Assert.Null(report.LocalDbOplogBacklog);
    }

    [Fact]
    public void UnreplicatedSite_StillRegistersTheHealthBridge()
    {
        // The fix is a GATE on what the reporter publishes, not a skipped registration.
        // Keeping the hosted service present means turning replication on is a config
        // change rather than a different service graph, and it keeps one code path for
        // both postures.
        var hosted = _host.Services.GetServices<IHostedService>();

        Assert.Contains(hosted, h => h is LocalDbReplicationStatusReporter);
    }

    [Fact]
    public void UnreplicatedSite_ReplicationEngine_StillResolvesAndIdles()
    {
        // Establishes the premise the row-80 fix rests on: the engine really does answer
        // false/0 here. If this ever starts returning null on its own, the gate becomes
        // redundant rather than wrong — but the test above still pins the observable
        // contract either way.
        var status = _host.Services.GetRequiredService<ISyncStatus>();

        Assert.False(status.Connected);
        Assert.Equal(0L, status.OplogBacklog);
    }
}