using Microsoft.Extensions.Options;
using MxGateway.Contracts.Proto;
using MxGateway.Server.Configuration;
using MxGateway.Server.Dashboard;
using MxGateway.Server.Metrics;
using MxGateway.Server.Sessions;
using MxGateway.Server.Workers;

namespace MxGateway.Tests.Gateway.Dashboard;

public sealed class DashboardSnapshotServiceTests
{
    [Fact]
    public void GetSnapshot_WhenRegistryEmpty_ReturnsEmptyOperationalState()
    {
        using GatewayMetrics metrics = new();
        DashboardSnapshotService service = CreateService(new SessionRegistry(), metrics);

        DashboardSnapshot snapshot = service.GetSnapshot();

        Assert.Empty(snapshot.Sessions);
        Assert.Empty(snapshot.Workers);
        Assert.Empty(snapshot.Faults);
        Assert.Contains(snapshot.Metrics, metric => metric.Name == "mxgateway.sessions.open" && metric.Value == 0);
        Assert.Equal("Healthy", snapshot.GatewayStatus);
        Assert.NotNull(snapshot.Configuration);
    }

    [Fact]
    public void GetSnapshot_ProjectsActiveAndFaultedSessionsWorkersMetricsAndFaults()
    {
        SessionRegistry registry = new();
        GatewaySession activeSession = CreateSession(
            "session-active",
            "client-one",
            DateTimeOffset.Parse("2026-04-26T10:00:00Z"));
        activeSession.AttachWorkerClient(new FakeWorkerClient("session-active", 1201, WorkerClientState.Ready));
        activeSession.MarkReady();
        GatewaySession faultedSession = CreateSession(
            "session-faulted",
            "client-two",
            DateTimeOffset.Parse("2026-04-26T10:01:00Z"));
        faultedSession.AttachWorkerClient(new FakeWorkerClient("session-faulted", 1202, WorkerClientState.Faulted));
        faultedSession.MarkFaulted("worker pipe disconnected");
        registry.TryAdd(activeSession);
        registry.TryAdd(faultedSession);
        using GatewayMetrics metrics = new();
        metrics.SessionOpened();
        metrics.SessionOpened();
        metrics.CommandStarted("Register");
        metrics.CommandFailed("Register", "WorkerFaulted", TimeSpan.FromMilliseconds(7));
        metrics.EventReceived("session-active", "OnDataChange");
        metrics.Fault("WorkerFaulted");
        DashboardSnapshotService service = CreateService(registry, metrics);

        DashboardSnapshot snapshot = service.GetSnapshot();

        Assert.Equal(2, snapshot.Sessions.Count);
        Assert.Equal("session-faulted", snapshot.Sessions[0].SessionId);
        Assert.Equal(SessionState.Faulted, snapshot.Sessions[0].State);
        Assert.Equal(2, snapshot.Workers.Count);
        Assert.Contains(snapshot.Metrics, metric => metric.Name == "mxgateway.commands.started" && metric.Value == 1);
        Assert.Contains(
            snapshot.Metrics,
            metric => metric.Name == "mxgateway.events.received"
                && metric.Dimension == "OnDataChange"
                && metric.Value == 1);
        DashboardFaultSummary fault = Assert.Single(snapshot.Faults);
        Assert.Equal("Worker", fault.Source);
        Assert.Equal("session-faulted", fault.SessionId);
        Assert.Equal("worker pipe disconnected", fault.Message);
    }

    [Fact]
    public void GetSnapshot_RedactsSecretsFromSessionAndFaultFields()
    {
        SessionRegistry registry = new();
        GatewaySession session = CreateSession(
            "session-redacted",
            "Bearer mxgw_admin_super-secret",
            DateTimeOffset.Parse("2026-04-26T10:00:00Z"),
            clientSessionName: "password=hunter2",
            clientCorrelationId: "token=abc123");
        session.MarkFaulted("secret=credential-value");
        registry.TryAdd(session);
        using GatewayMetrics metrics = new();
        DashboardSnapshotService service = CreateService(registry, metrics);

        DashboardSnapshot snapshot = service.GetSnapshot();

        DashboardSessionSummary summary = Assert.Single(snapshot.Sessions);
        Assert.Equal("Bearer mxgw_admin_[redacted]", summary.ClientIdentity);
        Assert.Equal("[redacted]", summary.ClientSessionName);
        Assert.Equal("[redacted]", summary.ClientCorrelationId);
        Assert.Equal("[redacted]", summary.LastFault);
        Assert.Equal("[redacted]", Assert.Single(snapshot.Faults).Message);
        Assert.Equal("[redacted]", snapshot.Configuration.Authentication.PepperSecretName);
    }

    [Fact]
    public void GetSnapshot_DoesNotMutateSessionOrWorkerState()
    {
        SessionRegistry registry = new();
        GatewaySession session = CreateSession(
            "session-active",
            "client-one",
            DateTimeOffset.Parse("2026-04-26T10:00:00Z"));
        FakeWorkerClient workerClient = new("session-active", 1201, WorkerClientState.Ready);
        session.AttachWorkerClient(workerClient);
        session.MarkReady();
        registry.TryAdd(session);
        using GatewayMetrics metrics = new();
        DashboardSnapshotService service = CreateService(registry, metrics);

        service.GetSnapshot();
        service.GetSnapshot();

        Assert.Equal(1, registry.ActiveCount);
        Assert.Equal(SessionState.Ready, session.State);
        Assert.Equal(WorkerClientState.Ready, workerClient.State);
        Assert.Equal(0, workerClient.StartCount);
        Assert.Equal(0, workerClient.ShutdownCount);
        Assert.Equal(0, workerClient.KillCount);
    }

    [Fact]
    public void GetSnapshot_AppliesRecentSessionAndFaultLimits()
    {
        SessionRegistry registry = new();
        GatewaySession olderSession = CreateSession(
            "session-older",
            "client-one",
            DateTimeOffset.Parse("2026-04-26T10:00:00Z"));
        GatewaySession newerSession = CreateSession(
            "session-newer",
            "client-two",
            DateTimeOffset.Parse("2026-04-26T10:01:00Z"));
        olderSession.MarkFaulted("older fault");
        newerSession.MarkFaulted("newer fault");
        registry.TryAdd(olderSession);
        registry.TryAdd(newerSession);
        using GatewayMetrics metrics = new();
        DashboardSnapshotService service = CreateService(
            registry,
            metrics,
            new GatewayOptions
            {
                Dashboard = new DashboardOptions
                {
                    SnapshotIntervalMilliseconds = 1,
                    RecentSessionLimit = 1,
                    RecentFaultLimit = 1,
                },
            });

        DashboardSnapshot snapshot = service.GetSnapshot();

        Assert.Equal("session-newer", Assert.Single(snapshot.Sessions).SessionId);
        Assert.Equal("session-newer", Assert.Single(snapshot.Faults).SessionId);
    }

    [Fact]
    public async Task WatchSnapshotsAsync_WhenSubscriberCancels_DisposesCleanly()
    {
        using GatewayMetrics metrics = new();
        DashboardSnapshotService service = CreateService(
            new SessionRegistry(),
            metrics,
            new GatewayOptions
            {
                Dashboard = new DashboardOptions
                {
                    SnapshotIntervalMilliseconds = 1,
                },
            });
        using CancellationTokenSource cancellation = new();
        await using IAsyncEnumerator<DashboardSnapshot> enumerator = service
            .WatchSnapshotsAsync(cancellation.Token)
            .GetAsyncEnumerator();

        Assert.True(await enumerator.MoveNextAsync().AsTask().WaitAsync(TimeSpan.FromSeconds(1)));
        await cancellation.CancelAsync();
        bool hasNext = await enumerator.MoveNextAsync().AsTask().WaitAsync(TimeSpan.FromSeconds(1));

        Assert.False(hasNext);
    }

    private static DashboardSnapshotService CreateService(
        SessionRegistry registry,
        GatewayMetrics metrics,
        GatewayOptions? options = null)
    {
        GatewayOptions resolvedOptions = options ?? new GatewayOptions
        {
            Dashboard = new DashboardOptions
            {
                SnapshotIntervalMilliseconds = 1,
            },
        };
        GatewayConfigurationProvider configurationProvider = new(Options.Create(resolvedOptions));

        return new DashboardSnapshotService(
            registry,
            metrics,
            configurationProvider,
            Options.Create(resolvedOptions));
    }

    private static GatewaySession CreateSession(
        string sessionId,
        string? clientIdentity,
        DateTimeOffset openedAt,
        string? clientSessionName = "test-session",
        string? clientCorrelationId = "client-correlation")
    {
        return new GatewaySession(
            sessionId,
            "mxaccess",
            $"mxaccess-gateway-1-{sessionId}",
            "nonce",
            clientIdentity,
            clientSessionName,
            clientCorrelationId,
            TimeSpan.FromSeconds(30),
            TimeSpan.FromSeconds(5),
            TimeSpan.FromSeconds(5),
            openedAt);
    }

    private sealed class FakeWorkerClient(
        string sessionId,
        int? processId,
        WorkerClientState state) : IWorkerClient
    {
        public string SessionId { get; } = sessionId;

        public int? ProcessId { get; } = processId;

        public WorkerClientState State { get; private set; } = state;

        public DateTimeOffset LastHeartbeatAt { get; } = DateTimeOffset.Parse("2026-04-26T10:02:00Z");

        public int StartCount { get; private set; }

        public int ShutdownCount { get; private set; }

        public int KillCount { get; private set; }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            StartCount++;
            return Task.CompletedTask;
        }

        public Task<WorkerCommandReply> InvokeAsync(
            WorkerCommand command,
            TimeSpan timeout,
            CancellationToken cancellationToken)
        {
            return Task.FromResult(new WorkerCommandReply());
        }

        public async IAsyncEnumerable<WorkerEvent> ReadEventsAsync(
            [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
        {
            await Task.CompletedTask;
            yield break;
        }

        public Task ShutdownAsync(
            TimeSpan timeout,
            CancellationToken cancellationToken)
        {
            ShutdownCount++;
            State = WorkerClientState.Closed;
            return Task.CompletedTask;
        }

        public void Kill(string reason)
        {
            KillCount++;
            State = WorkerClientState.Faulted;
        }

        public ValueTask DisposeAsync()
        {
            return ValueTask.CompletedTask;
        }
    }
}