using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using NSubstitute;
using ScadaLink.Commons.Entities.Audit;
using ScadaLink.Commons.Entities.Notifications;
using ScadaLink.Commons.Interfaces.Repositories;
using ScadaLink.Commons.Interfaces.Services;
using ScadaLink.Commons.Types.Enums;
using ScadaLink.NotificationOutbox.Delivery;
using ScadaLink.NotificationOutbox.Messages;

namespace ScadaLink.NotificationOutbox.Tests;

/// <summary>
/// M4 Bundle B (B2) — verifies the <see cref="NotificationOutboxActor"/>
/// dispatcher loop emits exactly ONE
/// <see cref="AuditChannel.Notification"/>/<see cref="AuditKind.NotifyDeliver"/>
/// audit row with <see cref="AuditStatus.Attempted"/> per attempt regardless of
/// the delivery outcome (success, transient, permanent). Terminal-state
/// emission is covered separately in
/// <see cref="NotificationOutboxActorTerminalEmissionTests"/>.
/// </summary>
public class NotificationOutboxActorAttemptEmissionTests : TestKit
{
    private readonly INotificationOutboxRepository _outboxRepository =
        Substitute.For<INotificationOutboxRepository>();

    private readonly INotificationRepository _notificationRepository =
        Substitute.For<INotificationRepository>();

    private readonly RecordingCentralAuditWriter _auditWriter = new();

    /// <summary>
    /// Recording writer so each test can assert on the events captured during
    /// one dispatch tick without depending on a concrete implementation.
    /// </summary>
    private sealed class RecordingCentralAuditWriter : ICentralAuditWriter
    {
        public List<AuditEvent> Events { get; } = new();
        public Func<AuditEvent, Task>? OnWrite { get; set; }

        public Task WriteAsync(AuditEvent evt, CancellationToken ct = default)
        {
            lock (Events)
            {
                Events.Add(evt);
            }

            return OnWrite?.Invoke(evt) ?? Task.CompletedTask;
        }
    }

    private IServiceProvider BuildServiceProvider(IEnumerable<INotificationDeliveryAdapter> adapters)
    {
        var services = new ServiceCollection();
        services.AddScoped(_ => _outboxRepository);
        services.AddScoped(_ => _notificationRepository);
        foreach (var adapter in adapters)
        {
            services.AddScoped<INotificationDeliveryAdapter>(_ => adapter);
        }

        return services.BuildServiceProvider();
    }

    private sealed class StubAdapter : INotificationDeliveryAdapter
    {
        private readonly Func<DeliveryOutcome> _outcome;
        public int CallCount;

        public StubAdapter(Func<DeliveryOutcome> outcome) { _outcome = outcome; }

        public NotificationType Type => NotificationType.Email;

        public Task<DeliveryOutcome> DeliverAsync(
            Notification notification, CancellationToken cancellationToken = default)
        {
            Interlocked.Increment(ref CallCount);
            return Task.FromResult(_outcome());
        }
    }

    private IActorRef CreateActor(IEnumerable<INotificationDeliveryAdapter> adapters)
    {
        return Sys.ActorOf(Props.Create(() => new NotificationOutboxActor(
            BuildServiceProvider(adapters),
            new NotificationOutboxOptions { DispatchInterval = TimeSpan.FromHours(1) },
            (ICentralAuditWriter)_auditWriter,
            NullLogger<NotificationOutboxActor>.Instance)));
    }

    private static Notification MakeNotification(
        Guid? notificationId = null,
        string sourceSite = "site-1",
        int retryCount = 0,
        Guid? originExecutionId = null)
    {
        return new Notification(
            (notificationId ?? Guid.NewGuid()).ToString("D"),
            NotificationType.Email,
            "ops-team",
            "Tank overflow",
            "Tank 3 level critical",
            sourceSite)
        {
            RetryCount = retryCount,
            CreatedAt = DateTimeOffset.UtcNow,
            SourceInstanceId = "instance-42",
            SourceScript = "AlarmScript",
            OriginExecutionId = originExecutionId,
        };
    }

    private void SetupSmtpRetryPolicy(int maxRetries, TimeSpan retryDelay)
    {
        var config = new SmtpConfiguration("smtp.example.com", "Basic", "noreply@example.com")
        {
            MaxRetries = maxRetries,
            RetryDelay = retryDelay,
        };
        _notificationRepository.GetAllSmtpConfigurationsAsync(Arg.Any<CancellationToken>())
            .Returns(new[] { config });
    }

    private List<AuditEvent> EventsByStatus(AuditStatus status)
    {
        lock (_auditWriter.Events)
        {
            return _auditWriter.Events.Where(e => e.Status == status).ToList();
        }
    }

    [Fact]
    public void Attempt_Success_EmitsOneEvent_KindNotifyDeliver_StatusAttempted()
    {
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var id = Guid.NewGuid();
        var notification = MakeNotification(notificationId: id, sourceSite: "site-alpha");
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Success("ops@example.com"));
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        AwaitAssert(() =>
        {
            var attempted = EventsByStatus(AuditStatus.Attempted);
            Assert.Single(attempted);
            var evt = attempted[0];
            Assert.Equal(AuditChannel.Notification, evt.Channel);
            Assert.Equal(AuditKind.NotifyDeliver, evt.Kind);
            Assert.Equal(id, evt.CorrelationId);
            Assert.Equal("ops-team", evt.Target);
            Assert.Equal("site-alpha", evt.SourceSiteId);
            Assert.Equal("instance-42", evt.SourceInstanceId);
            Assert.Equal("AlarmScript", evt.SourceScript);
            // Central dispatch: Actor is the system identity (no per-call user).
            Assert.Equal("system", evt.Actor);
            // Successful attempt: no error message.
            Assert.Null(evt.ErrorMessage);
        });
    }

    [Fact]
    public void Attempt_CarriesOriginExecutionId_AsExecutionId()
    {
        // Audit Log #23: the Attempted NotifyDeliver row must echo the
        // notification's OriginExecutionId so all rows for one run share an id.
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var executionId = Guid.NewGuid();
        var notification = MakeNotification(originExecutionId: executionId);
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Success("ops@example.com"));
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        AwaitAssert(() =>
        {
            var attempted = EventsByStatus(AuditStatus.Attempted);
            Assert.Single(attempted);
            Assert.Equal(executionId, attempted[0].ExecutionId);
        });
    }

    [Fact]
    public void Attempt_NullOriginExecutionId_HasNullExecutionId()
    {
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var notification = MakeNotification(originExecutionId: null);
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Success("ops@example.com"));
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        AwaitAssert(() =>
        {
            var attempted = EventsByStatus(AuditStatus.Attempted);
            Assert.Single(attempted);
            Assert.Null(attempted[0].ExecutionId);
        });
    }

    [Fact]
    public void Attempt_TransientFailure_EmitsEvent_StatusAttempted_ErrorMessageSet()
    {
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var notification = MakeNotification(retryCount: 1);
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Transient("smtp timeout"));
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        AwaitAssert(() =>
        {
            var attempted = EventsByStatus(AuditStatus.Attempted);
            Assert.Single(attempted);
            Assert.Equal(AuditKind.NotifyDeliver, attempted[0].Kind);
            Assert.Equal("smtp timeout", attempted[0].ErrorMessage);
        });
    }

    [Fact]
    public void Attempt_PermanentFailure_EmitsEvent_StatusAttempted_ErrorMessageSet()
    {
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var notification = MakeNotification();
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Permanent("invalid recipient address"));
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        AwaitAssert(() =>
        {
            var attempted = EventsByStatus(AuditStatus.Attempted);
            Assert.Single(attempted);
            Assert.Equal(AuditKind.NotifyDeliver, attempted[0].Kind);
            Assert.Equal("invalid recipient address", attempted[0].ErrorMessage);
        });
    }

    [Fact]
    public void AuditWriter_Throws_DeliveryStateUpdate_StillSucceeds()
    {
        // Audit failure must NEVER abort the user-facing action: the delivery
        // outcome must still be persisted via UpdateAsync.
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var notification = MakeNotification();
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Success("ops@example.com"));
        _auditWriter.OnWrite = _ => throw new InvalidOperationException("audit dead");
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        // Update of the notification row must still happen.
        AwaitAssert(() =>
        {
            _outboxRepository.Received(1).UpdateAsync(
                Arg.Is<Notification>(n => n.Status == NotificationStatus.Delivered),
                Arg.Any<CancellationToken>());
        });
    }

    [Fact]
    public void Attempt_RecordsOccurredAtUtc_AsUtc()
    {
        // The OccurredAtUtc on the emitted event must be UTC (all timestamps
        // are UTC throughout the system).
        SetupSmtpRetryPolicy(maxRetries: 5, retryDelay: TimeSpan.FromMinutes(1));
        var notification = MakeNotification();
        _outboxRepository.GetDueAsync(Arg.Any<DateTimeOffset>(), Arg.Any<int>(), Arg.Any<CancellationToken>())
            .Returns(new[] { notification });
        var adapter = new StubAdapter(() => DeliveryOutcome.Success("ops@example.com"));
        var actor = CreateActor([adapter]);

        actor.Tell(InternalMessages.DispatchTick.Instance);

        AwaitAssert(() =>
        {
            var attempted = EventsByStatus(AuditStatus.Attempted);
            Assert.Single(attempted);
            Assert.Equal(DateTimeKind.Utc, attempted[0].OccurredAtUtc.Kind);
        });
    }
}