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

namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;

/// <summary>
///     Opt-in fake <see cref="IDriverFactory"/> the <see cref="TwoNodeClusterHarness"/> can register
///     so a deployed driver actually reaches <c>Connected</c> (Healthy) in-process — no Docker sim and
///     no real backend. Materialises a <see cref="FakeReconnectDriver"/> for the <c>"Modbus"</c> driver
///     type (any other type returns <c>null</c>, mirroring <see cref="NullDriverFactory"/>).
/// </summary>
/// <remarks>
///     The DI wiring resolves <see cref="IDriverFactory"/> from the container; the production
///     <c>AddOtOpcUaRuntime()</c> seeds <see cref="NullDriverFactory"/> via <c>TryAddSingleton</c>, so a
///     harness that wants live drivers registers this fake first (its registration wins). Every
///     initialize/connect succeeds, so the wrapping <c>DriverInstanceActor</c> walks
///     <c>Connecting → Connected → Healthy</c> and (on <c>ReconnectDriver</c>) drives
///     <c>ForceReconnect → Reconnecting → re-initialize → Connected</c> without any fault injection.
/// </remarks>
public sealed class FakeReconnectDriverFactory : IDriverFactory
{
    /// <summary>The single driver type this fake factory materialises.</summary>
    public const string FakeDriverType = "Modbus";

    /// <summary>
    ///     Returns a <see cref="FakeReconnectDriver"/> when <paramref name="driverType"/> is
    ///     <see cref="FakeDriverType"/>; otherwise <c>null</c> (the host logs + skips the row).
    /// </summary>
    /// <param name="driverType">The driver type name from the deployed <c>DriverInstance</c> row.</param>
    /// <param name="driverInstanceId">The stable driver-instance identifier.</param>
    /// <param name="driverConfigJson">The driver configuration as a JSON string (ignored by the fake).</param>
    /// <returns>A new <see cref="FakeReconnectDriver"/>, or <c>null</c> for an unsupported type.</returns>
    public IDriver? TryCreate(string driverType, string driverInstanceId, string driverConfigJson)
        => driverType == FakeDriverType
            ? new FakeReconnectDriver(driverInstanceId, driverType)
            : null;

    /// <summary>Gets the driver-type names this factory can materialise.</summary>
    public IReadOnlyCollection<string> SupportedTypes { get; } = new[] { FakeDriverType };
}

/// <summary>
///     A minimal in-process <see cref="IDriver"/> whose connect/initialize path always succeeds, so the
///     wrapping <c>DriverInstanceActor</c> reaches <c>Connected</c> and publishes a
///     <see cref="DriverState.Healthy"/> snapshot. Reads/writes/subscribes are benign no-ops; this exists
///     only to let a deployed driver walk the Healthy ↔ Reconnecting FSM in-process for E2E tests.
/// </summary>
public sealed class FakeReconnectDriver : IDriver
{
    /// <summary>
    ///     Initializes a new <see cref="FakeReconnectDriver"/>.
    /// </summary>
    /// <param name="driverInstanceId">The stable logical driver-instance identifier.</param>
    /// <param name="driverType">The driver type name.</param>
    public FakeReconnectDriver(string driverInstanceId, string driverType)
    {
        DriverInstanceId = driverInstanceId;
        DriverType = driverType;
    }

    /// <summary>Gets the stable logical ID of this driver instance.</summary>
    public string DriverInstanceId { get; }

    /// <summary>Gets the driver type name (e.g. "Modbus").</summary>
    public string DriverType { get; }

    /// <summary>
    ///     Connect/initialize path — always succeeds (returns a completed task), so the actor self-Tells
    ///     <c>InitializeSucceeded</c> and becomes <c>Connected</c>. This is the method that makes connect
    ///     succeed; the FSM's reconnect path re-invokes it and it succeeds again.
    /// </summary>
    /// <param name="driverConfigJson">The driver configuration JSON (ignored).</param>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A completed task — initialization always succeeds.</returns>
    public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
        => Task.CompletedTask;

    /// <summary>Applies a config change in place — a no-op that always succeeds.</summary>
    /// <param name="driverConfigJson">The driver configuration JSON (ignored).</param>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A completed task — reinitialization always succeeds.</returns>
    public Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
        => Task.CompletedTask;

    /// <summary>Stops the driver — a no-op that always succeeds.</summary>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A completed task.</returns>
    public Task ShutdownAsync(CancellationToken cancellationToken)
        => Task.CompletedTask;

    /// <summary>Returns a <see cref="DriverState.Healthy"/> snapshot so deployed drivers publish health.</summary>
    /// <returns>A <see cref="DriverHealth"/> in the <see cref="DriverState.Healthy"/> state.</returns>
    public DriverHealth GetHealth() => new(DriverState.Healthy, DateTime.UtcNow, null);

    /// <summary>Returns a zero memory footprint (the fake holds no driver-attributable caches).</summary>
    /// <returns>Always <c>0</c>.</returns>
    public long GetMemoryFootprint() => 0;

    /// <summary>Flushes optional caches — a no-op (the fake holds none).</summary>
    /// <param name="cancellationToken">Cancellation token for the operation.</param>
    /// <returns>A completed task.</returns>
    public Task FlushOptionalCachesAsync(CancellationToken cancellationToken)
        => Task.CompletedTask;
}