using System.Text.Json;
using Akka.Actor;
using Akka.TestKit.Xunit2;
using Microsoft.Data.Sqlite;
using Microsoft.Extensions.Logging.Abstractions;
using ScadaLink.Commons.Entities.Audit;
using ScadaLink.Commons.Interfaces.Services;
using ScadaLink.Commons.Types.Enums;
using ScadaLink.SiteRuntime.Scripts;
using ScadaLink.StoreAndForward;

namespace ScadaLink.SiteRuntime.Tests.Scripts;

/// <summary>
/// Audit Log #23 — M4 Bundle C (Task C1): every script-initiated
/// <c>Notify.To("list").Send(...)</c> emits exactly one
/// <c>Notification</c>/<c>NotifySend</c> audit event via the wrapper inside
/// <see cref="ScriptRuntimeContext.NotifyTarget"/>. The audit emission is
/// best-effort: a thrown <see cref="IAuditWriter.WriteAsync"/> must never
/// abort the script's <c>Send</c> — the original <c>NotificationId</c> must
/// still flow back to the caller and the underlying S&amp;F enqueue must still
/// have happened.
/// </summary>
public class NotifySendAuditEmissionTests : TestKit, IAsyncLifetime, IDisposable
{
    /// <summary>
    /// In-memory <see cref="IAuditWriter"/> that records every event passed to
    /// <see cref="WriteAsync"/>. Optionally configurable to throw, simulating a
    /// catastrophic audit-writer failure that the wrapper must swallow per
    /// alog.md §7.
    /// </summary>
    private sealed class CapturingAuditWriter : IAuditWriter
    {
        public List<AuditEvent> Events { get; } = new();
        public Exception? ThrowOnWrite { get; set; }

        public Task WriteAsync(AuditEvent evt, CancellationToken ct = default)
        {
            if (ThrowOnWrite != null)
            {
                return Task.FromException(ThrowOnWrite);
            }

            Events.Add(evt);
            return Task.CompletedTask;
        }
    }

    private const string SiteId = "site-7";
    private const string InstanceName = "Plant.Pump3";
    private const string SourceScript = "ScriptActor:CheckPressure";
    private const string ListName = "Operators";
    private const string Subject = "Pump alarm";
    private const string Body = "Pump 3 tripped";

    /// <summary>
    /// Audit Log #23: a fixed per-execution id so the NotifySend test can
    /// assert <see cref="AuditEvent.ExecutionId"/> against a known value.
    /// </summary>
    private static readonly Guid TestExecutionId = Guid.NewGuid();

    private readonly SqliteConnection _keepAlive;
    private readonly StoreAndForwardStorage _storage;
    private readonly StoreAndForwardService _saf;

    public NotifySendAuditEmissionTests()
    {
        var dbName = $"NotifySendAudit_{Guid.NewGuid():N}";
        var connStr = $"Data Source={dbName};Mode=Memory;Cache=Shared";
        _keepAlive = new SqliteConnection(connStr);
        _keepAlive.Open();

        _storage = new StoreAndForwardStorage(connStr, NullLogger<StoreAndForwardStorage>.Instance);
        var options = new StoreAndForwardOptions
        {
            DefaultRetryInterval = TimeSpan.Zero,
            DefaultMaxRetries = 3,
            RetryTimerInterval = TimeSpan.FromMinutes(10)
        };
        _saf = new StoreAndForwardService(_storage, options, NullLogger<StoreAndForwardService>.Instance);
    }

    public async Task InitializeAsync() => await _storage.InitializeAsync();

    public Task DisposeAsync() => Task.CompletedTask;

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            _keepAlive.Dispose();
        }
        base.Dispose(disposing);
    }

    private ScriptRuntimeContext.NotifyHelper CreateHelper(
        IAuditWriter? auditWriter,
        string? sourceScript = SourceScript)
    {
        // siteCommunicationActor is unused by Send — pass a probe so the helper
        // is fully constructed.
        var probe = CreateTestProbe();
        return new ScriptRuntimeContext.NotifyHelper(
            _saf,
            probe.Ref,
            SiteId,
            InstanceName,
            sourceScript,
            TimeSpan.FromSeconds(3),
            NullLogger.Instance,
            TestExecutionId,
            auditWriter);
    }

    [Fact]
    public async Task Send_Success_EmitsOneEvent_KindNotifySend_StatusSubmitted()
    {
        var writer = new CapturingAuditWriter();
        var notify = CreateHelper(writer);

        var notificationId = await notify.To(ListName).Send(Subject, Body);

        Assert.False(string.IsNullOrEmpty(notificationId));
        Assert.Single(writer.Events);
        var evt = writer.Events[0];
        Assert.Equal(AuditChannel.Notification, evt.Channel);
        Assert.Equal(AuditKind.NotifySend, evt.Kind);
        Assert.Equal(AuditStatus.Submitted, evt.Status);
        Assert.Equal(AuditForwardState.Pending, evt.ForwardState);
        Assert.Equal(DateTimeKind.Utc, evt.OccurredAtUtc.Kind);
        Assert.NotEqual(Guid.Empty, evt.EventId);
        Assert.False(evt.PayloadTruncated);
        Assert.Null(evt.DurationMs);
        Assert.Null(evt.HttpStatus);
        Assert.Null(evt.ErrorMessage);
        Assert.Null(evt.ErrorDetail);
        // Outbound channel: Actor carries the calling script identity.
        Assert.Equal(SourceScript, evt.Actor);
    }

    [Fact]
    public async Task Send_PopulatesTarget_AsListName()
    {
        var writer = new CapturingAuditWriter();
        var notify = CreateHelper(writer);

        await notify.To(ListName).Send(Subject, Body);

        var evt = writer.Events[0];
        Assert.Equal(ListName, evt.Target);
    }

    [Fact]
    public async Task Send_PopulatesRequestSummary_AsSubjectBodyJson()
    {
        var writer = new CapturingAuditWriter();
        var notify = CreateHelper(writer);

        await notify.To(ListName).Send(Subject, Body);

        var evt = writer.Events[0];
        Assert.NotNull(evt.RequestSummary);
        // Round-trip the JSON to assert the exact shape, not raw text — the
        // contract is "JSON of {subject, body}", which downstream redaction
        // (M5) can reshape; M4 captures verbatim.
        using var doc = JsonDocument.Parse(evt.RequestSummary!);
        var root = doc.RootElement;
        Assert.Equal(JsonValueKind.Object, root.ValueKind);
        Assert.Equal(Subject, root.GetProperty("subject").GetString());
        Assert.Equal(Body, root.GetProperty("body").GetString());
    }

    [Fact]
    public async Task Send_AuditWriter_Throws_OriginalSendStillReturns()
    {
        var writer = new CapturingAuditWriter
        {
            ThrowOnWrite = new InvalidOperationException("audit writer down")
        };
        var notify = CreateHelper(writer);

        // The Send call must NOT bubble the audit-writer failure: the script
        // contract is that the notification is buffered and the id is returned
        // even when the audit pipeline is sick.
        var notificationId = await notify.To(ListName).Send(Subject, Body);

        Assert.False(string.IsNullOrEmpty(notificationId));

        // And the underlying S&F enqueue must still have happened — audit is
        // purely additive, never aborts the user-facing action.
        var buffered = await _saf.GetMessageByIdAsync(notificationId);
        Assert.NotNull(buffered);
        Assert.Equal(notificationId, buffered!.Id);

        Assert.Empty(writer.Events);
    }

    [Fact]
    public async Task Send_Provenance_PopulatedFromContext()
    {
        var writer = new CapturingAuditWriter();
        var notify = CreateHelper(writer);

        await notify.To(ListName).Send(Subject, Body);

        var evt = writer.Events[0];
        Assert.Equal(SiteId, evt.SourceSiteId);
        Assert.Equal(InstanceName, evt.SourceInstanceId);
        Assert.Equal(SourceScript, evt.SourceScript);
        // Outbound channel: Actor carries the calling script identity.
        Assert.Equal(SourceScript, evt.Actor);
    }

    [Fact]
    public async Task Send_NotificationIdParsed_AsCorrelationId()
    {
        var writer = new CapturingAuditWriter();
        var notify = CreateHelper(writer);

        var notificationId = await notify.To(ListName).Send(Subject, Body);

        // NotificationId is minted as Guid.NewGuid().ToString("N") — the 32-char
        // hex form, which Guid.TryParse accepts. The audit row's CorrelationId
        // must round-trip back to the same Guid value (the per-operation
        // lifecycle id). ExecutionId carries the per-execution id instead.
        Assert.True(Guid.TryParse(notificationId, out var expected),
            $"NotificationId '{notificationId}' should be a parseable Guid");
        var evt = writer.Events[0];
        Assert.NotNull(evt.CorrelationId);
        Assert.Equal(expected, evt.CorrelationId);
        Assert.Equal(TestExecutionId, evt.ExecutionId);
    }

    [Fact]
    public async Task Send_WithoutAuditWriter_StillReturnsNotificationId_AndEnqueues()
    {
        // Audit is opt-in (mirrors M2 Bundle F behaviour): a null writer must
        // degrade to a no-op audit path so tests / minimal hosts that don't
        // wire AddAuditLog still work.
        var notify = CreateHelper(auditWriter: null);

        var notificationId = await notify.To(ListName).Send(Subject, Body);

        Assert.False(string.IsNullOrEmpty(notificationId));
        var buffered = await _saf.GetMessageByIdAsync(notificationId);
        Assert.NotNull(buffered);
    }
}