using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;

/// <summary>
///     T15 — verifies the non-blocking historian-provisioning hook in
///     <see cref="AddressSpaceApplier.Apply"/>. The hook fires AFTER the address-space work and
///     dispatches <see cref="IHistorianProvisioning.EnsureTagsAsync"/> fire-and-forget, so a slow or
///     throwing provisioner can never block or break a deploy on the OPC UA publish actor's pinned
///     thread.
/// </summary>
public sealed class AddressSpaceApplierProvisioningTests
{
    /// <summary>Capturing <see cref="IHistorianProvisioning"/> double. Records the requests it was
    /// handed and signals a <see cref="TaskCompletionSource"/> when invoked, so a test can await the
    /// fire-and-forget dispatch deterministically (never poll/sleep). A <see cref="Throw"/> flag
    /// simulates a synchronous provisioner fault.</summary>
    private sealed class CapturingProvisioner : IHistorianProvisioning
    {
        private readonly TaskCompletionSource _called = new(TaskCreationOptions.RunContinuationsAsynchronously);

        /// <summary>Gets the requests the hook handed to <see cref="EnsureTagsAsync"/>.</summary>
        public List<HistorianTagProvisionRequest> Seen { get; } = new();

        /// <summary>When true, <see cref="EnsureTagsAsync"/> throws synchronously (a fault before any await).</summary>
        public bool Throw { get; init; }

        /// <summary>Completes once <see cref="EnsureTagsAsync"/> has been invoked.</summary>
        public Task Called => _called.Task;

        /// <inheritdoc />
        public Task<HistorianProvisionResult> EnsureTagsAsync(
            IReadOnlyList<HistorianTagProvisionRequest> requests, CancellationToken ct)
        {
            if (Throw)
            {
                _called.TrySetResult();
                throw new InvalidOperationException("boom");
            }

            Seen.AddRange(requests);
            _called.TrySetResult();
            return Task.FromResult(new HistorianProvisionResult(requests.Count, requests.Count, 0, 0));
        }
    }

    /// <summary>The hook provisions ONLY historized added tags, with the resolved historian name
    /// (override when set, else the driver-side FullName).</summary>
    [Fact]
    public async Task Apply_provisions_only_historized_added_tags()
    {
        var prov = new CapturingProvisioner();
        var applier = new AddressSpaceApplier(NullOpcUaAddressSpaceSink.Instance, NullLogger<AddressSpaceApplier>.Instance, prov);

        // Leaf display name "Temp"; historian override "Pump1.Temp".
        var plan = PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32"),
            NonHistorizedTag(displayName: "Run", dataType: "Boolean"));

        var outcome = applier.Apply(plan);

        outcome.RebuildCalled.ShouldBeFalse(); // PureAdd — no rebuild; provisioning still fires
        outcome.AddedNodes.ShouldBeGreaterThan(0);

        // Fire-and-forget: await the capturing double's signal so the assertion is deterministic.
        await prov.Called.WaitAsync(TimeSpan.FromSeconds(5), TestContext.Current.CancellationToken);
        prov.Seen.Count.ShouldBe(1);
        prov.Seen[0].TagName.ShouldBe("Pump1.Temp"); // resolved historian name (override)
        prov.Seen[0].DataType.ShouldBe(DriverDataType.Float32);
        prov.Seen[0].Description.ShouldBe("Temp"); // leaf display name
    }

    /// <summary>A null/blank historian-name override resolves to the driver-side FullName — mirroring
    /// the materialiser's resolution exactly.</summary>
    [Fact]
    public async Task Apply_resolves_historian_name_from_fullname_when_override_blank()
    {
        var prov = new CapturingProvisioner();
        var applier = new AddressSpaceApplier(NullOpcUaAddressSpaceSink.Instance, NullLogger<AddressSpaceApplier>.Instance, prov);

        // IsHistorized but no override → historian name falls back to FullName ("40001").
        var plan = PlanWithAddedTags(
            HistorizedTag(displayName: "Speed", historianName: null, dataType: "Int32", fullName: "40001"));

        applier.Apply(plan);

        await prov.Called.WaitAsync(TimeSpan.FromSeconds(5), TestContext.Current.CancellationToken);
        prov.Seen.Count.ShouldBe(1);
        prov.Seen[0].TagName.ShouldBe("40001");
        prov.Seen[0].DataType.ShouldBe(DriverDataType.Int32);
    }

    /// <summary>A synchronously-throwing provisioner must NOT block or break the publish: the
    /// synchronous <see cref="AddressSpaceApplier.Apply"/> still completes its address-space work and
    /// returns its normal outcome.</summary>
    [Fact]
    public void Provisioner_throw_does_not_block_publish()
    {
        var applier = new AddressSpaceApplier(
            NullOpcUaAddressSpaceSink.Instance,
            NullLogger<AddressSpaceApplier>.Instance,
            new CapturingProvisioner { Throw = true });

        var outcome = applier.Apply(PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32")));

        outcome.RebuildCalled.ShouldBeFalse(); // PureAdd — no rebuild; Apply still completed + provisioned
    }

    /// <summary>The default ctor (no provisioner) binds the no-op <see cref="NullHistorianProvisioning"/>
    /// and never faults a deploy — preserving every existing call site.</summary>
    [Fact]
    public void Default_ctor_uses_null_provisioning_and_does_not_throw()
    {
        var applier = new AddressSpaceApplier(NullOpcUaAddressSpaceSink.Instance, NullLogger<AddressSpaceApplier>.Instance);

        var outcome = applier.Apply(PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32")));

        outcome.RebuildCalled.ShouldBeFalse(); // PureAdd — no rebuild; default no-op provisioning still safe
        outcome.AddedNodes.ShouldBeGreaterThan(0);
    }

    /// <summary>An added historized tag whose DataType string is not a <see cref="DriverDataType"/> is
    /// skipped (no request) — the hook never throws on an unparseable type.</summary>
    [Fact]
    public async Task Apply_skips_added_tag_with_unparseable_datatype()
    {
        var prov = new CapturingProvisioner();
        var applier = new AddressSpaceApplier(NullOpcUaAddressSpaceSink.Instance, NullLogger<AddressSpaceApplier>.Instance, prov);

        // "Float" is NOT a DriverDataType member (the members are Float32/Float64); it must be skipped.
        var plan = PlanWithAddedTags(
            HistorizedTag(displayName: "Bad", historianName: "Pump1.Bad", dataType: "Float"),
            HistorizedTag(displayName: "Good", historianName: "Pump1.Good", dataType: "Float32"));

        applier.Apply(plan);

        await prov.Called.WaitAsync(TimeSpan.FromSeconds(5), TestContext.Current.CancellationToken);
        prov.Seen.Count.ShouldBe(1);
        prov.Seen[0].TagName.ShouldBe("Pump1.Good");
    }

    /// <summary>Capturing <see cref="ILogger{T}"/> that records every log line and signals a
    /// <see cref="TaskCompletionSource{TResult}"/> the first time a "historian provisioning completed" tally is
    /// emitted, so the fire-and-forget continuation's log can be awaited deterministically.</summary>
    private sealed class CapturingLogger : ILogger<AddressSpaceApplier>
    {
        private readonly TaskCompletionSource<string> _provisioningLogged =
            new(TaskCreationOptions.RunContinuationsAsynchronously);

        /// <summary>Completes with the rendered message of the first provisioning-completed tally logged.</summary>
        public Task<string> ProvisioningLogged => _provisioningLogged.Task;

        public IDisposable BeginScope<TState>(TState state) where TState : notnull => NullScope.Instance;

        public bool IsEnabled(LogLevel logLevel) => true;

        public void Log<TState>(
            LogLevel logLevel, EventId eventId, TState state, Exception? exception,
            Func<TState, Exception?, string> formatter)
        {
            var message = formatter(state, exception);
            if (logLevel == LogLevel.Information &&
                message.Contains("historian provisioning completed", StringComparison.Ordinal))
            {
                _provisioningLogged.TrySetResult(message);
            }
        }

        private sealed class NullScope : IDisposable
        {
            public static readonly NullScope Instance = new();
            public void Dispose() { }
        }
    }

    /// <summary>Issue 2 (observability): a fully-successful provisioning (Ensured>0, Failed=0, Skipped=0) — the
    /// case that previously logged NOTHING — now emits an Information tally, so a successful provisioning is
    /// observable rather than silent.</summary>
    [Fact]
    public async Task Apply_logs_an_information_tally_on_a_fully_successful_provisioning()
    {
        var logger = new CapturingLogger();
        var applier = new AddressSpaceApplier(
            NullOpcUaAddressSpaceSink.Instance, logger, new CapturingProvisioner());

        applier.Apply(PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32")));

        var message = await logger.ProvisioningLogged.WaitAsync(TimeSpan.FromSeconds(5), TestContext.Current.CancellationToken);
        message.ShouldContain("dispatched=1");
        message.ShouldContain("ensured=1");
        message.ShouldContain("failed=0");
    }

    /// <summary>Issue 2 (observability): the no-op <see cref="NullHistorianProvisioning"/> path is now
    /// DETECTABLE — it reports Requested=0 regardless of input, so a tally showing dispatched=1 but requested=0
    /// unmistakably flags "provisioning is not wired", the invisibility that let the dormant-provisioner bug
    /// ship unnoticed.</summary>
    [Fact]
    public async Task Apply_logs_a_detectable_tally_for_the_noop_provisioning_path()
    {
        var logger = new CapturingLogger();
        var applier = new AddressSpaceApplier(NullOpcUaAddressSpaceSink.Instance, logger);

        applier.Apply(PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32")));

        var message = await logger.ProvisioningLogged.WaitAsync(TimeSpan.FromSeconds(5), TestContext.Current.CancellationToken);
        message.ShouldContain("dispatched=1");  // we DID hand one request to EnsureTagsAsync
        message.ShouldContain("requested=0");   // ...but the no-op acknowledges nothing ⇒ dormant
    }

    /// <summary>Capturing <see cref="IHistorizedTagSubscriptionSink"/> double. Records the add/remove
    /// ref deltas the applier feeds it. A <see cref="Throw"/> flag simulates a faulting feed.</summary>
    private sealed class CapturingSubscriptionSink : IHistorizedTagSubscriptionSink
    {
        /// <summary>Ref pairs the applier fed as ADDED (mux ref + historian name).</summary>
        public List<HistorizedTagRef> Added { get; } = new();

        /// <summary>Ref pairs the applier fed as REMOVED.</summary>
        public List<HistorizedTagRef> Removed { get; } = new();

        /// <summary>When true, <see cref="UpdateHistorizedRefs"/> throws synchronously.</summary>
        public bool Throw { get; init; }

        /// <inheritdoc />
        public void UpdateHistorizedRefs(IReadOnlyList<HistorizedTagRef> added, IReadOnlyList<HistorizedTagRef> removed)
        {
            if (Throw) throw new InvalidOperationException("boom");
            Added.AddRange(added);
            Removed.AddRange(removed);
        }
    }

    /// <summary>The feed pushes ONLY historized added refs, resolved (override-or-FullName) exactly like
    /// the provisioning hook — non-historized tags never reach the recorder.</summary>
    [Fact]
    public void Apply_feeds_historized_added_refs_to_the_subscription_sink()
    {
        var sink = new CapturingSubscriptionSink();
        var applier = new AddressSpaceApplier(
            NullOpcUaAddressSpaceSink.Instance, NullLogger<AddressSpaceApplier>.Instance,
            historizedSubscriptions: sink);

        var plan = PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32"),
            HistorizedTag(displayName: "Speed", historianName: null, dataType: "Int32", fullName: "40001"),
            NonHistorizedTag(displayName: "Run", dataType: "Boolean"));

        applier.Apply(plan);

        // Each ref carries BOTH identifiers: the override tag feeds (mux ref = FullName "ref", historian
        // name = override "Pump1.Temp"); the no-override tag feeds (FullName "40001" as both).
        sink.Added.ShouldBe(new[]
        {
            new HistorizedTagRef("ref", "Pump1.Temp"),
            new HistorizedTagRef("40001", "40001"),
        }, ignoreOrder: true);
        sink.Removed.ShouldBeEmpty();
    }

    /// <summary>Removed historized tags are fed as REMOVED refs; a changed tag whose historian override is
    /// renamed feeds the old ref removed + the new ref added (the recorder converges the full set).</summary>
    [Fact]
    public void Apply_feeds_removed_and_renamed_historized_refs()
    {
        var sink = new CapturingSubscriptionSink();
        var applier = new AddressSpaceApplier(
            NullOpcUaAddressSpaceSink.Instance, NullLogger<AddressSpaceApplier>.Instance,
            historizedSubscriptions: sink);

        var removedTag = HistorizedTag(displayName: "Old", historianName: "Pump1.Old", dataType: "Float32");
        // Same TagId ("tag-T"), historian override renamed A → B (both historized) → remove A, add B.
        var prev = HistorizedTag(displayName: "T", historianName: "Pump1.A", dataType: "Float32");
        var cur = HistorizedTag(displayName: "T", historianName: "Pump1.B", dataType: "Float32");

        var plan = new AddressSpacePlan(
            AddedEquipment: Array.Empty<EquipmentNode>(),
            RemovedEquipment: Array.Empty<EquipmentNode>(),
            ChangedEquipment: Array.Empty<AddressSpacePlan.EquipmentDelta>(),
            AddedDrivers: Array.Empty<DriverInstancePlan>(),
            RemovedDrivers: Array.Empty<DriverInstancePlan>(),
            ChangedDrivers: Array.Empty<AddressSpacePlan.DriverDelta>(),
            AddedAlarms: Array.Empty<ScriptedAlarmPlan>(),
            RemovedAlarms: Array.Empty<ScriptedAlarmPlan>(),
            ChangedAlarms: Array.Empty<AddressSpacePlan.AlarmDelta>())
        {
            RemovedRawTags = new[] { removedTag },
            ChangedRawTags = new[] { new AddressSpacePlan.RawTagDelta(prev, cur) },
        };

        applier.Apply(plan);

        // All three tags default FullName "ref" (the mux ref); the override rename changes only the
        // historian name, so the changed tag feeds removed (ref, Pump1.A) + added (ref, Pump1.B).
        sink.Added.ShouldBe(new[] { new HistorizedTagRef("ref", "Pump1.B") }, ignoreOrder: true);
        sink.Removed.ShouldBe(new[]
        {
            new HistorizedTagRef("ref", "Pump1.Old"),
            new HistorizedTagRef("ref", "Pump1.A"),
        }, ignoreOrder: true);
    }

    /// <summary>A synchronously-throwing subscription sink must NOT block or break the publish — the
    /// address-space work still completes and <see cref="AddressSpaceApplier.Apply"/> returns its outcome.</summary>
    [Fact]
    public void Subscription_sink_throw_does_not_block_publish()
    {
        var applier = new AddressSpaceApplier(
            NullOpcUaAddressSpaceSink.Instance,
            NullLogger<AddressSpaceApplier>.Instance,
            historizedSubscriptions: new CapturingSubscriptionSink { Throw = true });

        var outcome = applier.Apply(PlanWithAddedTags(
            HistorizedTag(displayName: "Temp", historianName: "Pump1.Temp", dataType: "Float32")));

        outcome.RebuildCalled.ShouldBeFalse(); // PureAdd — no rebuild; Apply still completed + provisioned
    }

    // v3 Batch 4: historized value tags are RAW tags — the mux ref + historian default are the RawPath
    // (== NodeId). The `fullName` param plays the role of the RawPath here (kept as a param name so the
    // existing assertions — HistorizedTagRef("ref"/"40001", …) — read unchanged).
    private static RawTagPlan HistorizedTag(string displayName, string? historianName, string dataType, string fullName = "ref")
        => new("tag-" + displayName, NodeId: fullName, ParentNodeId: null, DriverInstanceId: "drv", Name: displayName,
            DataType: dataType, Writable: false, Alarm: null, ReferencingEquipmentPaths: Array.Empty<string>(),
            IsHistorized: true, HistorianTagname: historianName);

    private static RawTagPlan NonHistorizedTag(string displayName, string dataType)
        => new("tag-" + displayName, NodeId: "ref", ParentNodeId: null, DriverInstanceId: "drv", Name: displayName,
            DataType: dataType, Writable: false, Alarm: null, ReferencingEquipmentPaths: Array.Empty<string>(),
            IsHistorized: false, HistorianTagname: null);

    private static AddressSpacePlan PlanWithAddedTags(params RawTagPlan[] tags) => new(
        AddedEquipment: Array.Empty<EquipmentNode>(),
        RemovedEquipment: Array.Empty<EquipmentNode>(),
        ChangedEquipment: Array.Empty<AddressSpacePlan.EquipmentDelta>(),
        AddedDrivers: Array.Empty<DriverInstancePlan>(),
        RemovedDrivers: Array.Empty<DriverInstancePlan>(),
        ChangedDrivers: Array.Empty<AddressSpacePlan.DriverDelta>(),
        AddedAlarms: Array.Empty<ScriptedAlarmPlan>(),
        RemovedAlarms: Array.Empty<ScriptedAlarmPlan>(),
        ChangedAlarms: Array.Empty<AddressSpacePlan.AlarmDelta>())
    {
        AddedRawTags = tags,
    };
}
