using Opc.Ua;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;

/// <summary>
///     Unit tests for the filter-aware
///     <see cref="OpcUaClientDriver.ReadEventsAsync(string, EventHistoryRequest, System.Threading.CancellationToken)"/>
///     overload (PR-12 / #284). The driver-level wire path needs a live <see cref="ISession"/>
///     so the round-trip-through-Session.HistoryReadAsync test lands as an integration test;
///     here we cover the surface that's reachable without a session: SelectClause translation,
///     default-clause fallback, and the EventFilter projection helper.
/// </summary>
[Trait("Category", "Unit")]
public sealed class OpcUaClientHistoryEventsTests
{
    [Fact]
    public void DefaultEventSelectClauses_carries_the_standard_BaseEventType_columns()
    {
        // The fallback set must match BuildHistoryEvent on the server side so a client that
        // doesn't customize the EventFilter still sees recognizable BaseEventType columns
        // (EventId, SourceName, Time, Message, Severity, ReceiveTime).
        var defaults = OpcUaClientDriver.DefaultEventSelectClauses;
        defaults.Count.ShouldBe(6);
        defaults.Select(d => d.FieldName).ShouldBe(
            ["EventId", "SourceName", "Time", "Message", "Severity", "ReceiveTime"]);
        // None of the defaults reach into a typed path — they're all rooted at BaseEventType
        // (TypeDefinitionId=null sentinel).
        defaults.All(d => d.TypeDefinitionId is null).ShouldBeTrue();
        defaults.All(d => d.BrowsePath.Count == 1).ShouldBeTrue();
    }

    [Fact]
    public void ToOpcEventFilter_translates_each_SimpleAttributeSpec_to_a_SimpleAttributeOperand()
    {
        var clauses = new List<SimpleAttributeSpec>
        {
            new(null, ["EventId"], "EventId"),
            new(null, ["Severity"], "Severity"),
            new("i=2782" /* ConditionType */, [], "ConditionId"),
        };

        var filter = OpcUaClientDriver.ToOpcEventFilter(clauses, whereClause: null);

        filter.SelectClauses.Count.ShouldBe(3);

        filter.SelectClauses[0].TypeDefinitionId.ShouldBe(ObjectTypeIds.BaseEventType);
        filter.SelectClauses[0].BrowsePath.Count.ShouldBe(1);
        filter.SelectClauses[0].BrowsePath[0].Name.ShouldBe("EventId");
        filter.SelectClauses[0].AttributeId.ShouldBe(Attributes.Value);

        filter.SelectClauses[1].BrowsePath[0].Name.ShouldBe("Severity");

        // Typed-path entry: TypeDefinitionId parses to the supplied NodeId text and
        // BrowsePath stays empty (= "the typed node itself").
        filter.SelectClauses[2].TypeDefinitionId.ShouldBe(NodeId.Parse("i=2782"));
        filter.SelectClauses[2].BrowsePath.Count.ShouldBe(0);
    }

    [Fact]
    public void ToOpcEventFilter_with_null_where_clause_leaves_WhereClause_empty()
    {
        // Empty WhereClause is the OPC UA equivalent of "no filter" — every event matches.
        // The client driver only attaches a WhereClause when one was decoded successfully;
        // a null/empty ContentFilterSpec should never produce an Elements collection.
        var clauses = new List<SimpleAttributeSpec>
        {
            new(null, ["EventId"], "EventId"),
        };

        var filter = OpcUaClientDriver.ToOpcEventFilter(clauses, whereClause: null);

        filter.WhereClause.ShouldNotBeNull();
        filter.WhereClause.Elements.Count.ShouldBe(0);
    }

    [Fact]
    public void ToOpcEventFilter_with_malformed_where_clause_bytes_swallows_and_yields_empty_filter()
    {
        // Defense-in-depth: a corrupt encoded filter must not throw out of the helper.
        // The driver chooses to drop the where-clause silently rather than fail the whole
        // HistoryReadEvents call (best-effort projection per IHistoryProvider contract).
        var clauses = new List<SimpleAttributeSpec>
        {
            new(null, ["EventId"], "EventId"),
        };
        var bogus = new ContentFilterSpec([0xFF, 0xFE, 0xFD]);

        // Provide a real MessageContext so the BinaryDecoder path is exercised; without it
        // the helper never attempts to decode and the test wouldn't cover the catch branch.
#pragma warning disable CS0618 // ServiceMessageContext() — telemetry-context overload is irrelevant for unit decode.
        var ctx = new ServiceMessageContext();
#pragma warning restore CS0618
        var filter = OpcUaClientDriver.ToOpcEventFilter(clauses, bogus, ctx);

        filter.SelectClauses.Count.ShouldBe(1);
        // Either the decoder produced a default ContentFilter (Elements=0) or the catch
        // branch left the wire-default in place — either way no exception escaped.
        filter.WhereClause.ShouldNotBeNull();
    }

    [Fact]
    public async Task ReadEventsAsync_filter_overload_without_initialize_throws_InvalidOperationException()
    {
        // Same uninitialized-driver guard the rest of the IHistoryProvider methods use.
        // Confirms the new overload is wired through RequireSession() rather than silently
        // returning an empty batch on a never-connected driver (which would mask wiring bugs).
        using var drv = new OpcUaClientDriver(new OpcUaClientDriverOptions(), "opcua-evt-uninit");
        var request = new EventHistoryRequest(
            StartTime: DateTime.UtcNow.AddMinutes(-5),
            EndTime: DateTime.UtcNow,
            NumValuesPerNode: 100,
            SelectClauses: null,
            WhereClause: null);
        await Should.ThrowAsync<InvalidOperationException>(async () =>
            await drv.ReadEventsAsync(
                fullReference: "ns=2;s=AlarmsNotifier",
                request: request,
                cancellationToken: TestContext.Current.CancellationToken));
    }

    [Fact]
    public async Task ReadEventsAsync_filter_overload_rejects_null_request()
    {
        using var drv = new OpcUaClientDriver(new OpcUaClientDriverOptions(), "opcua-evt-null");
        await Should.ThrowAsync<ArgumentNullException>(async () =>
            await drv.ReadEventsAsync(
                fullReference: "ns=2;s=AlarmsNotifier",
                request: null!,
                cancellationToken: TestContext.Current.CancellationToken));
    }

    [Fact]
    public async Task IHistoryProvider_filter_aware_default_throws_NotSupportedException_for_other_drivers()
    {
        // Other drivers that haven't opted in to the filter-aware overload must still see
        // the IHistoryProvider default — same shape as the parameterless overload's default.
        // We use a no-op stub to exercise the interface default's path.
        IHistoryProvider stub = new NotImplementedHistoryStub();
        var request = new EventHistoryRequest(
            StartTime: DateTime.UtcNow.AddMinutes(-5),
            EndTime: DateTime.UtcNow,
            NumValuesPerNode: 100,
            SelectClauses: null,
            WhereClause: null);
        await Should.ThrowAsync<NotSupportedException>(async () =>
            await stub.ReadEventsAsync(
                fullReference: "ns=2;s=AlarmsNotifier",
                request: request,
                cancellationToken: TestContext.Current.CancellationToken));
    }

    private sealed class NotImplementedHistoryStub : IHistoryProvider
    {
        public Task<Core.Abstractions.HistoryReadResult> ReadRawAsync(string fullReference, DateTime startUtc, DateTime endUtc,
            uint maxValuesPerNode, CancellationToken cancellationToken)
            => throw new NotImplementedException();

        public Task<Core.Abstractions.HistoryReadResult> ReadProcessedAsync(string fullReference, DateTime startUtc, DateTime endUtc,
            TimeSpan interval, HistoryAggregateType aggregate, CancellationToken cancellationToken)
            => throw new NotImplementedException();
    }
}