lmxopcua/tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeSessionAdapter.cs

using Opc.Ua;
using ZB.MOM.WW.OtOpcUa.Client.Shared.Adapters;

namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Fakes;

/// <summary>
/// Test double for <see cref="ISessionAdapter" /> used to simulate reads, writes, browsing, history, and failover callbacks.
/// </summary>
internal sealed class FakeSessionAdapter : ISessionAdapter
{
    private readonly List<FakeSubscriptionAdapter> _createdSubscriptions = [];
    private Action<bool>? _keepAliveCallback;

    /// <summary>
    /// Gets a value indicating whether the fake session has been closed through the client disconnect path.
    /// </summary>
    public bool Closed { get; private set; }

    /// <summary>
    /// Gets a value indicating whether the fake session has been disposed.
    /// </summary>
    public bool Disposed { get; private set; }
    /// <summary>Gets the number of times ReadValueAsync has been called.</summary>
    public int ReadCount { get; private set; }
    /// <summary>Gets the number of times WriteValueAsync has been called.</summary>
    public int WriteCount { get; private set; }
    /// <summary>Gets the number of times BrowseAsync has been called.</summary>
    public int BrowseCount { get; private set; }
    /// <summary>Gets the number of times BrowseNextAsync has been called.</summary>
    public int BrowseNextCount { get; private set; }
    /// <summary>Gets the number of times HistoryReadRawAsync has been called.</summary>
    public int HistoryReadRawCount { get; private set; }
    /// <summary>Gets the number of times HistoryReadAggregateAsync has been called.</summary>
    public int HistoryReadAggregateCount { get; private set; }

    // Configurable responses
    /// <summary>Gets or sets the data value returned by read operations.</summary>
    public DataValue? ReadResponse { get; set; }
    /// <summary>Gets or sets a function to generate read responses dynamically based on the node ID.</summary>
    public Func<NodeId, DataValue>? ReadResponseFunc { get; set; }
    /// <summary>Gets or sets the status code returned by write operations.</summary>
    public StatusCode WriteResponse { get; set; } = StatusCodes.Good;
    /// <summary>Gets or sets a value indicating whether read operations should throw an exception.</summary>
    public bool ThrowOnRead { get; set; }
    /// <summary>Gets or sets a value indicating whether write operations should throw an exception.</summary>
    public bool ThrowOnWrite { get; set; }
    /// <summary>Gets or sets a value indicating whether browse operations should throw an exception.</summary>
    public bool ThrowOnBrowse { get; set; }

    /// <summary>Gets or sets the browse references returned by browse operations.</summary>
    public ReferenceDescriptionCollection BrowseResponse { get; set; } = [];
    /// <summary>Gets or sets the continuation point for browse operations.</summary>
    public byte[]? BrowseContinuationPoint { get; set; }
    /// <summary>Gets or sets the browse references returned by browse-next operations.</summary>
    public ReferenceDescriptionCollection BrowseNextResponse { get; set; } = [];
    /// <summary>Gets or sets the continuation point for browse-next operations.</summary>
    public byte[]? BrowseNextContinuationPoint { get; set; }

    /// <summary>Gets or sets the historical values returned by raw history-read operations.</summary>
    public List<DataValue> HistoryReadRawResponse { get; set; } = [];
    /// <summary>Gets or sets the historical values returned by aggregate history-read operations.</summary>
    public List<DataValue> HistoryReadAggregateResponse { get; set; } = [];
    /// <summary>Gets or sets a value indicating whether raw history-read operations should throw an exception.</summary>
    public bool ThrowOnHistoryReadRaw { get; set; }
    /// <summary>Gets or sets a value indicating whether aggregate history-read operations should throw an exception.</summary>
    public bool ThrowOnHistoryReadAggregate { get; set; }

    /// <summary>
    /// Gets or sets the next fake subscription returned when the client creates a monitored-item subscription.
    /// If unset, the fake builds a new subscription automatically.
    /// </summary>
    public FakeSubscriptionAdapter? NextSubscription { get; set; }

    /// <summary>
    /// Gets the fake subscriptions created by this session so tests can inspect replay and cleanup behavior.
    /// </summary>
    public IReadOnlyList<FakeSubscriptionAdapter> CreatedSubscriptions => _createdSubscriptions;

    /// <inheritdoc />
    public bool Connected { get; set; } = true;

    /// <inheritdoc />
    public string SessionId { get; set; } = "ns=0;i=12345";

    /// <inheritdoc />
    public string SessionName { get; set; } = "FakeSession";

    /// <inheritdoc />
    public string EndpointUrl { get; set; } = "opc.tcp://localhost:4840";

    /// <inheritdoc />
    public string ServerName { get; set; } = "FakeServer";

    /// <inheritdoc />
    public string SecurityMode { get; set; } = "None";

    /// <inheritdoc />
    public string SecurityPolicyUri { get; set; } = "http://opcfoundation.org/UA/SecurityPolicy#None";

    /// <inheritdoc />
    public NamespaceTable NamespaceUris { get; set; } = new();

    /// <inheritdoc />
    public void RegisterKeepAliveHandler(Action<bool> callback)
    {
        _keepAliveCallback = callback;
    }

    /// <inheritdoc />
    public Task<DataValue> ReadValueAsync(NodeId nodeId, CancellationToken ct)
    {
        ReadCount++;
        if (ThrowOnRead)
            throw new ServiceResultException(StatusCodes.BadNodeIdUnknown, "Node not found");

        if (ReadResponseFunc != null)
            return Task.FromResult(ReadResponseFunc(nodeId));

        return Task.FromResult(ReadResponse ?? new DataValue(new Variant(0), StatusCodes.Good));
    }

    /// <inheritdoc />
    public Task<StatusCode> WriteValueAsync(NodeId nodeId, DataValue value, CancellationToken ct)
    {
        WriteCount++;
        if (ThrowOnWrite)
            throw new ServiceResultException(StatusCodes.BadNodeIdUnknown, "Node not found");
        return Task.FromResult(WriteResponse);
    }

    /// <inheritdoc />
    public Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseAsync(
        NodeId nodeId, uint nodeClassMask, CancellationToken ct)
    {
        BrowseCount++;
        if (ThrowOnBrowse)
            throw new ServiceResultException(StatusCodes.BadNodeIdUnknown, "Node not found");
        return Task.FromResult((BrowseContinuationPoint, BrowseResponse));
    }

    /// <inheritdoc />
    public Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseNextAsync(
        byte[] continuationPoint, CancellationToken ct)
    {
        BrowseNextCount++;
        return Task.FromResult((BrowseNextContinuationPoint, BrowseNextResponse));
    }

    /// <inheritdoc />
    public Task<IReadOnlyList<DataValue>> HistoryReadRawAsync(
        NodeId nodeId, DateTime startTime, DateTime endTime, int maxValues, CancellationToken ct)
    {
        HistoryReadRawCount++;
        if (ThrowOnHistoryReadRaw)
            throw new ServiceResultException(StatusCodes.BadHistoryOperationUnsupported, "History not supported");
        return Task.FromResult<IReadOnlyList<DataValue>>(HistoryReadRawResponse);
    }

    /// <inheritdoc />
    public Task<IReadOnlyList<DataValue>> HistoryReadAggregateAsync(
        NodeId nodeId, DateTime startTime, DateTime endTime, NodeId aggregateId, double intervalMs,
        CancellationToken ct)
    {
        HistoryReadAggregateCount++;
        if (ThrowOnHistoryReadAggregate)
            throw new ServiceResultException(StatusCodes.BadHistoryOperationUnsupported, "History not supported");
        return Task.FromResult<IReadOnlyList<DataValue>>(HistoryReadAggregateResponse);
    }

    /// <summary>
    /// Optional gate that, when set, holds <see cref="CreateSubscriptionAsync" /> open until completed, so a test can keep
    /// a subscribe in flight while something else (a failover) happens. Signalled via <see cref="CreateSubscriptionEntered" />.
    /// </summary>
    public TaskCompletionSource? CreateSubscriptionGate { get; set; }

    /// <summary>Completed when <see cref="CreateSubscriptionAsync" /> is entered while a gate is set.</summary>
    public TaskCompletionSource CreateSubscriptionEntered { get; } =
        new(TaskCreationOptions.RunContinuationsAsynchronously);

    /// <inheritdoc />
    public async Task<ISubscriptionAdapter> CreateSubscriptionAsync(int publishingIntervalMs, CancellationToken ct)
    {
        if (CreateSubscriptionGate is { } gate)
        {
            CreateSubscriptionEntered.TrySetResult();
            await gate.Task;
        }

        lock (_createdSubscriptions)
        {
            var sub = NextSubscription ?? new FakeSubscriptionAdapter();
            NextSubscription = null;
            _createdSubscriptions.Add(sub);
            return sub;
        }
    }

    /// <summary>
    /// Number of times <see cref="CallMethodAsync"/> was invoked so tests can assert
    /// acknowledgment workflows reached the session adapter.
    /// </summary>
    public int CallMethodCount { get; private set; }

    /// <summary>
    /// When set, <see cref="CallMethodAsync"/> throws this exception — used to simulate
    /// a bad method call status surfacing as a <see cref="ServiceResultException"/>.
    /// </summary>
    public Exception? CallMethodException { get; set; }

    /// <summary>
    /// Records the input arguments passed to each <see cref="CallMethodAsync"/> invocation.
    /// Index 0 is the first call, index 1 the second, etc.
    /// </summary>
    public List<object[]> CallMethodInputArgs { get; } = [];

    /// <summary>
    /// Records the object node id passed to each <see cref="CallMethodAsync"/> invocation,
    /// so tests can assert which condition object a method was invoked on.
    /// </summary>
    public List<NodeId> CallMethodObjectIds { get; } = [];

    /// <summary>
    /// Records the method node id passed to each <see cref="CallMethodAsync"/> invocation,
    /// so tests can assert the correct Part 9 method (e.g. Enable/Disable) was invoked.
    /// </summary>
    public List<NodeId> CallMethodMethodIds { get; } = [];

    /// <inheritdoc />
    public Task<IList<object>?> CallMethodAsync(NodeId objectId, NodeId methodId, object[] inputArguments,
        CancellationToken ct = default)
    {
        CallMethodCount++;
        CallMethodObjectIds.Add(objectId);
        CallMethodMethodIds.Add(methodId);
        CallMethodInputArgs.Add(inputArguments);
        if (CallMethodException != null)
            throw CallMethodException;
        return Task.FromResult<IList<object>?>(null);
    }

    /// <inheritdoc />
    public Task CloseAsync(CancellationToken ct)
    {
        Closed = true;
        Connected = false;
        return Task.CompletedTask;
    }

    /// <summary>
    /// Marks the fake session as disposed so tests can verify cleanup after disconnect or failover.
    /// </summary>
    public void Dispose()
    {
        Disposed = true;
        Connected = false;
    }

    /// <summary>
    ///     Simulates a keep-alive event.
    /// </summary>
    /// <param name="isGood">Whether the keep-alive status is good.</param>
    public void SimulateKeepAlive(bool isGood)
    {
        _keepAliveCallback?.Invoke(isGood);
    }
}