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

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

internal sealed class FakeSessionFactory : ISessionFactory
{
    private readonly List<FakeSessionAdapter> _createdSessions = [];
    private readonly Queue<FakeSessionAdapter> _sessions = new();

    public int CreateCallCount { get; private set; }
    public bool ThrowOnCreate { get; set; }
    public string? LastEndpointUrl { get; private set; }

    /// <summary>
    /// Optional gate that, when set, blocks <see cref="CreateSessionAsync" /> until completed.
    /// Lets tests hold a failover loop in-flight to exercise re-entrancy.
    /// </summary>
    public TaskCompletionSource? CreateGate { get; set; }

    public IReadOnlyList<FakeSessionAdapter> CreatedSessions => _createdSessions;

    public async Task<ISessionAdapter> CreateSessionAsync(
        ApplicationConfiguration config, EndpointDescription endpoint, string sessionName,
        uint sessionTimeoutMs, UserIdentity identity, CancellationToken ct)
    {
        CreateCallCount++;
        LastEndpointUrl = endpoint.EndpointUrl;

        if (CreateGate != null)
            await CreateGate.Task;

        if (ThrowOnCreate)
            throw new InvalidOperationException("FakeSessionFactory configured to fail.");

        FakeSessionAdapter session;
        if (_sessions.Count > 0)
            session = _sessions.Dequeue();
        else
            session = new FakeSessionAdapter
            {
                EndpointUrl = endpoint.EndpointUrl,
                ServerName = endpoint.Server?.ApplicationName?.Text ?? "FakeServer",
                SecurityMode = endpoint.SecurityMode.ToString(),
                SecurityPolicyUri = endpoint.SecurityPolicyUri ?? string.Empty
            };

        // Ensure endpoint URL matches
        session.EndpointUrl = endpoint.EndpointUrl;
        _createdSessions.Add(session);
        return session;
    }

    /// <summary>
    ///     Enqueues a session adapter to be returned on the next call to CreateSessionAsync.
    /// </summary>
    public void EnqueueSession(FakeSessionAdapter session)
    {
        _sessions.Enqueue(session);
    }
}