using ZB.MOM.WW.OtOpcUa.Core.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Drivers;

/// <summary>
///     A minimal <see cref="IDriver"/> + <see cref="IAlarmSource"/> that accepts every acknowledge and raises
///     nothing — the host's own running driver for tests that route a client acknowledge but drive the alarm
///     transitions themselves. Since lmxopcua#765 an ack to a driver that is not running (or is stubbed) is
///     reverted, so such a test must start the owning driver for the ack to stand.
/// </summary>
internal sealed class AckingAlarmDriver : IDriver, IAlarmSource
{
    private int _acks;
    private bool _alarmsSubscribed;

    /// <inheritdoc />
    public string DriverInstanceId { get; private set; } = string.Empty;

    /// <inheritdoc />
    public string DriverType { get; private set; } = string.Empty;

    /// <summary>How many acknowledge requests the driver accepted.</summary>
    public int Acks => Volatile.Read(ref _acks);

    /// <summary>True once the driver child reached Connected and opened its alarm subscription.</summary>
    public bool AlarmsSubscribed => Volatile.Read(ref _alarmsSubscribed);

    /// <summary>Sets the identity once the factory is asked to create it.</summary>
    /// <param name="id">The driver instance id.</param>
    /// <param name="type">The driver type.</param>
    public void Bind(string id, string type)
    {
        DriverInstanceId = id;
        DriverType = type;
    }

    /// <inheritdoc />
    public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken) => Task.CompletedTask;

    /// <inheritdoc />
    public Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken) => Task.CompletedTask;

    /// <inheritdoc />
    public Task ShutdownAsync(CancellationToken cancellationToken) => Task.CompletedTask;

    /// <inheritdoc />
    public DriverHealth GetHealth() => new(DriverState.Healthy, DateTime.UtcNow, LastError: null);

    /// <inheritdoc />
    public Task<IAlarmSubscriptionHandle> SubscribeAlarmsAsync(
        IReadOnlyList<string> sourceNodeIds, CancellationToken cancellationToken)
    {
        Volatile.Write(ref _alarmsSubscribed, true);
        return Task.FromResult<IAlarmSubscriptionHandle>(new Handle());
    }

    /// <inheritdoc />
    public Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken) =>
        Task.CompletedTask;

    /// <inheritdoc />
    public Task AcknowledgeAsync(
        IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements, CancellationToken cancellationToken)
    {
        Interlocked.Add(ref _acks, acknowledgements.Count);
        return Task.CompletedTask;
    }

    /// <inheritdoc />
    public event EventHandler<AlarmEventArgs>? OnAlarmEvent
    {
        add { }
        remove { }
    }

    private sealed class Handle : IAlarmSubscriptionHandle
    {
        public string DiagnosticId => "acking-alarm-sub";
    }
}

/// <summary>Factory handing the host one shared <see cref="AckingAlarmDriver"/> for a single driver type.</summary>
/// <param name="supportedType">The driver type this factory creates.</param>
internal sealed class AckingAlarmDriverFactory(string supportedType) : IDriverFactory
{
    /// <summary>The driver every spawn of <paramref name="supportedType"/> receives.</summary>
    public AckingAlarmDriver Driver { get; } = new();

    /// <inheritdoc />
    public IDriver? TryCreate(string driverType, string driverInstanceId, string driverConfigJson)
    {
        if (!string.Equals(driverType, supportedType, StringComparison.Ordinal)) return null;
        Driver.Bind(driverInstanceId, driverType);
        return Driver;
    }

    /// <inheritdoc />
    public IReadOnlyCollection<string> SupportedTypes => [supportedType];
}