using Microsoft.Extensions.Logging.Abstractions;
using Moq;
using ScadaLink.Commons.Entities.Audit;
using ScadaLink.Commons.Interfaces.Services;
using ScadaLink.Commons.Types;
using ScadaLink.Commons.Types.Enums;
using ScadaLink.SiteRuntime.Scripts;

namespace ScadaLink.SiteRuntime.Tests.Scripts;

/// <summary>
/// Audit Log #23 — M2 Bundle F (Task F1): every script-initiated
/// <c>ExternalSystem.Call</c> emits exactly one <c>ApiOutbound</c>/<c>ApiCall</c>
/// audit event via the wrapper inside
/// <see cref="ScriptRuntimeContext.ExternalSystemHelper"/>. The audit emission
/// is best-effort: a thrown <see cref="IAuditWriter.WriteAsync"/> must never
/// abort the script's call, and the original <see cref="ExternalCallResult"/>
/// (or original exception) must surface to the caller unchanged.
/// </summary>
public class ExternalSystemCallAuditEmissionTests
{
    /// <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.
    /// </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-77";
    private const string InstanceName = "Plant.Pump42";
    private const string SourceScript = "ScriptActor:CheckPressure";

    private static ScriptRuntimeContext.ExternalSystemHelper CreateHelper(
        IExternalSystemClient client,
        IAuditWriter? auditWriter)
    {
        return new ScriptRuntimeContext.ExternalSystemHelper(
            client,
            InstanceName,
            NullLogger.Instance,
            auditWriter,
            SiteId,
            SourceScript);
    }

    [Fact]
    public async Task Call_Success_EmitsOneEvent_Channel_ApiOutbound_Kind_ApiCall_Status_Delivered()
    {
        var client = new Mock<IExternalSystemClient>();
        client
            .Setup(c => c.CallAsync("ERP", "GetOrder", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .ReturnsAsync(new ExternalCallResult(true, "{}", null));
        var writer = new CapturingAuditWriter();

        var helper = CreateHelper(client.Object, writer);
        var result = await helper.Call("ERP", "GetOrder");

        Assert.True(result.Success);
        Assert.Single(writer.Events);
        var evt = writer.Events[0];
        Assert.Equal(AuditChannel.ApiOutbound, evt.Channel);
        Assert.Equal(AuditKind.ApiCall, evt.Kind);
        Assert.Equal(AuditStatus.Delivered, evt.Status);
        Assert.Equal("ERP.GetOrder", evt.Target);
        Assert.Equal(AuditForwardState.Pending, evt.ForwardState);
        Assert.Equal(DateTimeKind.Utc, evt.OccurredAtUtc.Kind);
        Assert.NotEqual(Guid.Empty, evt.EventId);
        Assert.False(evt.PayloadTruncated);
    }

    [Fact]
    public async Task Call_HTTP500_EmitsEvent_Status_Failed_HttpStatus_500_ErrorMessage_Set()
    {
        var client = new Mock<IExternalSystemClient>();
        client
            .Setup(c => c.CallAsync("ERP", "GetOrder", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .ReturnsAsync(new ExternalCallResult(false, null, "Transient error: HTTP 500 from ERP: Internal Server Error"));
        var writer = new CapturingAuditWriter();

        var helper = CreateHelper(client.Object, writer);
        var result = await helper.Call("ERP", "GetOrder");

        Assert.False(result.Success);
        Assert.Single(writer.Events);
        var evt = writer.Events[0];
        Assert.Equal(AuditStatus.Failed, evt.Status);
        Assert.Equal(500, evt.HttpStatus);
        Assert.False(string.IsNullOrEmpty(evt.ErrorMessage));
        Assert.Contains("500", evt.ErrorMessage);
    }

    [Fact]
    public async Task Call_HTTP400_EmitsEvent_Status_Failed_HttpStatus_400()
    {
        var client = new Mock<IExternalSystemClient>();
        client
            .Setup(c => c.CallAsync("ERP", "GetOrder", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .ReturnsAsync(new ExternalCallResult(false, null, "Permanent error: HTTP 400 from ERP: Bad Request"));
        var writer = new CapturingAuditWriter();

        var helper = CreateHelper(client.Object, writer);
        var result = await helper.Call("ERP", "GetOrder");

        Assert.False(result.Success);
        Assert.Single(writer.Events);
        var evt = writer.Events[0];
        Assert.Equal(AuditStatus.Failed, evt.Status);
        Assert.Equal(400, evt.HttpStatus);
    }

    [Fact]
    public async Task Call_ClientThrows_NetworkException_EmitsEvent_Status_Failed_ErrorMessage_FromException()
    {
        var client = new Mock<IExternalSystemClient>();
        var networkEx = new HttpRequestException("network down");
        client
            .Setup(c => c.CallAsync("ERP", "GetOrder", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .ThrowsAsync(networkEx);
        var writer = new CapturingAuditWriter();

        var helper = CreateHelper(client.Object, writer);
        var thrown = await Assert.ThrowsAsync<HttpRequestException>(() => helper.Call("ERP", "GetOrder"));
        Assert.Same(networkEx, thrown);

        Assert.Single(writer.Events);
        var evt = writer.Events[0];
        Assert.Equal(AuditStatus.Failed, evt.Status);
        Assert.Null(evt.HttpStatus);
        Assert.Equal("network down", evt.ErrorMessage);
        Assert.NotNull(evt.ErrorDetail);
        Assert.Contains("HttpRequestException", evt.ErrorDetail);
    }

    [Fact]
    public async Task AuditWriter_Throws_Script_Call_Returns_Original_Result_Unchanged()
    {
        var client = new Mock<IExternalSystemClient>();
        var expected = new ExternalCallResult(true, "{\"v\":1}", null);
        client
            .Setup(c => c.CallAsync("ERP", "GetOrder", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .ReturnsAsync(expected);
        var writer = new CapturingAuditWriter
        {
            ThrowOnWrite = new InvalidOperationException("audit writer down")
        };

        var helper = CreateHelper(client.Object, writer);
        var result = await helper.Call("ERP", "GetOrder");

        Assert.Same(expected, result);
        Assert.Empty(writer.Events);
    }

    [Fact]
    public async Task Provenance_Populated_FromContext()
    {
        var client = new Mock<IExternalSystemClient>();
        client
            .Setup(c => c.CallAsync("ERP", "GetOrder", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .ReturnsAsync(new ExternalCallResult(true, null, null));
        var writer = new CapturingAuditWriter();

        var helper = CreateHelper(client.Object, writer);
        var beforeId = Guid.NewGuid();

        await helper.Call("ERP", "GetOrder");

        var evt = writer.Events[0];
        Assert.NotEqual(beforeId, evt.EventId);
        Assert.NotEqual(Guid.Empty, evt.EventId);
        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);
        Assert.Null(evt.CorrelationId);
    }

    [Fact]
    public async Task DurationMs_Recorded_NonZero()
    {
        var client = new Mock<IExternalSystemClient>();
        client
            .Setup(c => c.CallAsync("ERP", "Slow", It.IsAny<IReadOnlyDictionary<string, object?>?>(), It.IsAny<CancellationToken>()))
            .Returns(async () =>
            {
                await Task.Delay(20);
                return new ExternalCallResult(true, null, null);
            });
        var writer = new CapturingAuditWriter();

        var helper = CreateHelper(client.Object, writer);
        await helper.Call("ERP", "Slow");

        var evt = writer.Events[0];
        Assert.NotNull(evt.DurationMs);
        Assert.True(evt.DurationMs >= 0, $"DurationMs={evt.DurationMs} should be >= 0");
        Assert.True(evt.DurationMs <= 5000, $"DurationMs={evt.DurationMs} should be <= 5000");
    }
}