using Microsoft.Extensions.Logging.Abstractions;
using Opc.Ua;
using Opc.Ua.Server;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using HistorianRead = ZB.MOM.WW.OtOpcUa.Core.Abstractions.HistoryReadResult;
using SdkHistoryReadResult = Opc.Ua.HistoryReadResult;

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

/// <summary>
///     HistoryReadEvents projects every field a historical alarm event can supply — <c>EventType</c> (the stored alarm
///     type name mapped to its Part 9 type, an unmodelled one to <c>AlarmConditionType</c>), <c>ConditionName</c>, and
///     <c>SourceNode</c> when the event's alarm id resolves to a materialised condition — and honours the request's
///     where-clause (an <c>OfType</c> by the type tree; any other operator against the projected fields). These used to
///     project <see cref="Variant.Null"/> and the where-clause was ignored.
/// </summary>
public sealed class NodeManagerHistoryReadEventsProjectionTests : IDisposable
{
    private static CancellationToken Ct => TestContext.Current.CancellationToken;
    private static readonly DateTime T0 = new(2026, 10, 22, 8, 0, 0, DateTimeKind.Utc);
    private readonly string _pkiRoot = Path.Combine(Path.GetTempPath(), $"otopcua-evtproj-{Guid.NewGuid():N}");

    private const string Equipment = "eq-proj";

    private static readonly HistoricalEvent[] Events =
    [
        new("e-limit", Equipment, T0, T0, "hi", 700, EventTypeName: "LimitAlarm", ConditionName: "HighTemp", AlarmId: "alarm-1"),
        new("e-offnormal", Equipment, T0.AddSeconds(1), T0, "off", 500, EventTypeName: "OffNormalAlarm", ConditionName: "Door", AlarmId: "alarm-gone"),
        new("e-untyped", Equipment, T0.AddSeconds(2), T0, "x", 300),
        new("e-bogus", Equipment, T0.AddSeconds(3), T0, "y", 900, EventTypeName: "Folder", ConditionName: "Odd"),
    ];

    [Fact]
    public async Task EventType_ConditionName_and_a_resolvable_SourceNode_are_projected()
    {
        var (host, server, nm, notifier) = await BootAsync();
        var condition = nm.TryGetAlarmCondition("alarm-1")!.NodeId;

        var history = Read(server, nm, notifier, Select("EventId", "EventType", "ConditionName", "SourceNode"), where: null);

        var rows = history.Events.ToDictionary(e => System.Text.Encoding.UTF8.GetString((byte[])e.EventFields[0].Value));
        rows["e-limit"].EventFields[1].Value.ShouldBe(ObjectTypeIds.LimitAlarmType);
        rows["e-limit"].EventFields[2].Value.ShouldBe("HighTemp");
        rows["e-limit"].EventFields[3].Value.ShouldBe(condition, "the alarm id resolves to the materialised condition — the live events' SourceNode");

        rows["e-offnormal"].EventFields[1].Value.ShouldBe(ObjectTypeIds.OffNormalAlarmType);
        rows["e-offnormal"].EventFields[3].Value.ShouldBeNull("no condition is materialised for that alarm id");

        // No stored type: still an alarm condition (every historical row is alarm history); an unrecognised or non-event
        // type name is not passed through as a non-event type.
        rows["e-untyped"].EventFields[1].Value.ShouldBe(ObjectTypeIds.AlarmConditionType);
        rows["e-untyped"].EventFields[2].Value.ShouldBeNull();
        rows["e-bogus"].EventFields[1].Value.ShouldBe(ObjectTypeIds.AlarmConditionType);

        await host.DisposeAsync();
    }

    [Fact]
    public async Task An_OfType_where_clause_keeps_only_events_of_that_type_or_a_subtype()
    {
        var (host, server, nm, notifier) = await BootAsync();

        Ids(Read(server, nm, notifier, Select("EventId"), OfType(ObjectTypeIds.LimitAlarmType))).ShouldBe(["e-limit"]);
        Ids(Read(server, nm, notifier, Select("EventId"), OfType(ObjectTypeIds.OffNormalAlarmType))).ShouldBe(["e-offnormal"]);
        // A supertype keeps its subtypes: every row is an AlarmConditionType (positive control — the filter is not
        // simply dropping everything typed).
        Ids(Read(server, nm, notifier, Select("EventId"), OfType(ObjectTypeIds.AlarmConditionType)))
            .ShouldBe(["e-limit", "e-offnormal", "e-untyped", "e-bogus"]);
        // An unrelated event type keeps nothing (GoodNoData).
        Ids(Read(server, nm, notifier, Select("EventId"), OfType(ObjectTypeIds.AuditEventType))).ShouldBeEmpty();
        await host.DisposeAsync();
    }

    [Fact]
    public async Task A_field_where_clause_is_evaluated_against_the_projected_fields()
    {
        var (host, server, nm, notifier) = await BootAsync();
        var where = new ContentFilter();
        where.Push(FilterOperator.GreaterThan,
            new SimpleAttributeOperand(ObjectTypeIds.BaseEventType, new QualifiedName("Severity")) { AttributeId = Attributes.Value },
            new LiteralOperand(new Variant((ushort)600)));

        Ids(Read(server, nm, notifier, Select("EventId"), where)).ShouldBe(["e-limit", "e-bogus"]);
        await host.DisposeAsync();
    }

    private static string[] Ids(HistoryEvent h) =>
        h.Events.Select(e => System.Text.Encoding.UTF8.GetString((byte[])e.EventFields[0].Value)).ToArray();

    private static ContentFilter OfType(NodeId type)
    {
        var f = new ContentFilter();
        f.Push(FilterOperator.OfType, new LiteralOperand(new Variant(type)));
        return f;
    }

    private static SimpleAttributeOperandCollection Select(params string[] leaves)
    {
        var c = new SimpleAttributeOperandCollection();
        foreach (var leaf in leaves)
            c.Add(new SimpleAttributeOperand(ObjectTypeIds.BaseEventType, new QualifiedName(leaf)) { AttributeId = Attributes.Value });
        return c;
    }

    private static HistoryEvent Read(OtOpcUaSdkServer server, OtOpcUaNodeManager nm, NodeId notifier,
        SimpleAttributeOperandCollection select, ContentFilter? where)
    {
        var details = new ReadEventDetails
        {
            StartTime = T0.AddHours(-1),
            EndTime = T0.AddHours(1),
            NumValuesPerNode = 100,
            Filter = new EventFilter { SelectClauses = select, WhereClause = where ?? new ContentFilter() },
        };
        var context = new OperationContext(new RequestHeader(), secureChannelContext: null, RequestType.HistoryRead, identity: null);
        var results = new List<SdkHistoryReadResult> { null! };
        var errors = new List<ServiceResult> { null! };
        nm.HistoryRead(context, details, TimestampsToReturn.Both, releaseContinuationPoints: false,
            new List<HistoryReadValueId> { new() { NodeId = notifier } }, results, errors);
        StatusCode.IsGood(errors[0].StatusCode).ShouldBeTrue($"HistoryRead failed: {errors[0].StatusCode}");
        return (HistoryEvent)ExtensionObject.ToEncodeable(results[0].HistoryData);
    }

    private async Task<(OpcUaApplicationHost Host, OtOpcUaSdkServer Server, OtOpcUaNodeManager Nm, NodeId Notifier)> BootAsync()
    {
        var started = await OpcUaHostStart.StartAsync(
            port => new OpcUaApplicationHost(
                new OpcUaApplicationHostOptions
                {
                    ApplicationName = "OtOpcUa.HistoryReadEventsProjectionTest",
                    ApplicationUri = $"urn:OtOpcUa.HistoryReadEventsProjectionTest:{Guid.NewGuid():N}",
                    OpcUaPort = port,
                    PublicHostname = "localhost",
                    PkiStoreRoot = _pkiRoot,
                },
                NullLogger<OpcUaApplicationHost>.Instance),
            () => new OtOpcUaSdkServer(), Ct);
        var nm = started.Server.NodeManager!;
        nm.HistorianDataSource = new FixedEventsSource(Events);
        nm.EnsureFolder(Equipment, parentNodeId: null, displayName: "Equipment", realm: AddressSpaceRealm.Uns);
        nm.MaterialiseAlarmCondition("alarm-1", Equipment, "HighTemp", "LimitAlarm", severity: 700, realm: AddressSpaceRealm.Uns);
        return (started.Host, started.Server, nm, nm.TryGetFolder(Equipment)!.NodeId);
    }

    private sealed class FixedEventsSource(IReadOnlyList<HistoricalEvent> events) : IHistorianDataSource
    {
        public Task<HistorianRead> ReadRawAsync(string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode,
            CancellationToken cancellationToken) =>
            NullHistorianDataSource.Instance.ReadRawAsync(fullReference, startUtc, endUtc, maxValuesPerNode, cancellationToken);

        public Task<HistorianRead> ReadProcessedAsync(string fullReference, DateTime startUtc, DateTime endUtc, TimeSpan interval,
            HistoryAggregateType aggregate, CancellationToken cancellationToken) =>
            NullHistorianDataSource.Instance.ReadProcessedAsync(fullReference, startUtc, endUtc, interval, aggregate, cancellationToken);

        public Task<HistorianRead> ReadAtTimeAsync(string fullReference, IReadOnlyList<DateTime> timestampsUtc,
            CancellationToken cancellationToken) =>
            NullHistorianDataSource.Instance.ReadAtTimeAsync(fullReference, timestampsUtc, cancellationToken);

        public Task<HistoricalEventsResult> ReadEventsAsync(string? sourceName, DateTime startUtc, DateTime endUtc, int maxEvents,
            CancellationToken cancellationToken) =>
            Task.FromResult(new HistoricalEventsResult(events.Where(e => e.EventTimeUtc >= startUtc && e.EventTimeUtc < endUtc).ToList(), null));

        public HistorianHealthSnapshot GetHealthSnapshot() => NullHistorianDataSource.Instance.GetHealthSnapshot();

        public void Dispose() { }
    }

    public void Dispose()
    {
        if (Directory.Exists(_pkiRoot))
        {
            try { Directory.Delete(_pkiRoot, recursive: true); }
            catch { /* best-effort cleanup */ }
        }
    }
}