using Microsoft.Extensions.Logging.Abstractions;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Commons.OpcUa;

namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;

/// <summary>
///     Integration tests for the F10b production binding: boot a real <see cref="OtOpcUaSdkServer"/>
///     through <see cref="OpcUaApplicationHost"/>, attach a <see cref="SdkAddressSpaceSink"/>,
///     drive <c>WriteValue</c>/<c>WriteAlarmState</c>/<c>RebuildAddressSpace</c>, and verify the
///     <see cref="OtOpcUaNodeManager"/> reflects the writes.
/// </summary>
public sealed class SdkAddressSpaceSinkTests : IDisposable
{
    private static CancellationToken Ct => TestContext.Current.CancellationToken;

    private readonly string _pkiRoot = Path.Combine(
        Path.GetTempPath(),
        $"otopcua-sink-{Guid.NewGuid():N}");

    /// <summary>Verifies that WriteValue creates and updates variables in the OPC UA node manager.</summary>
    [Fact]
    public async Task WriteValue_creates_and_updates_variable_in_node_manager()
    {
        var (host, server) = await BootAsync();
        var sink = new SdkAddressSpaceSink(server.NodeManager!);

        sink.WriteValue("eq-1/temp", 22.5, OpcUaQuality.Good, DateTime.UtcNow);
        sink.WriteValue("eq-1/temp", 23.1, OpcUaQuality.Good, DateTime.UtcNow);
        sink.WriteValue("eq-1/pressure", 100, OpcUaQuality.Uncertain, DateTime.UtcNow);

        server.NodeManager!.VariableCount.ShouldBe(2);

        await host.DisposeAsync();
    }

    /// <summary>Verifies that WriteAlarmState creates a dedicated node distinct from value writes.</summary>
    [Fact]
    public async Task WriteAlarmState_creates_dedicated_node_distinct_from_value_writes()
    {
        var (host, server) = await BootAsync();
        var sink = new SdkAddressSpaceSink(server.NodeManager!);

        sink.WriteAlarmState("alarm-7", active: true, acknowledged: false, DateTime.UtcNow);
        sink.WriteValue("eq-1/temp", 22.5, OpcUaQuality.Good, DateTime.UtcNow);

        server.NodeManager!.VariableCount.ShouldBe(2);

        await host.DisposeAsync();
    }

    /// <summary>Verifies that RebuildAddressSpace clears all registered variables.</summary>
    [Fact]
    public async Task RebuildAddressSpace_clears_all_registered_variables()
    {
        var (host, server) = await BootAsync();
        var sink = new SdkAddressSpaceSink(server.NodeManager!);

        sink.WriteValue("a", 1, OpcUaQuality.Good, DateTime.UtcNow);
        sink.WriteValue("b", 2, OpcUaQuality.Good, DateTime.UtcNow);
        sink.WriteAlarmState("alarm-c", true, false, DateTime.UtcNow);
        server.NodeManager!.VariableCount.ShouldBe(3);

        sink.RebuildAddressSpace();
        server.NodeManager.VariableCount.ShouldBe(0);

        // After rebuild, subsequent writes start fresh.
        sink.WriteValue("a", 99, OpcUaQuality.Good, DateTime.UtcNow);
        server.NodeManager.VariableCount.ShouldBe(1);

        await host.DisposeAsync();
    }

    /// <summary>Verifies that NullOpcUaAddressSpaceSink does not crash on any call.</summary>
    [Fact]
    public async Task NullOpcUaAddressSpaceSink_does_not_crash_on_any_call()
    {
        // Sanity check that the F10 fallback still works — production callers default to
        // NullOpcUaAddressSpaceSink when no SDK NodeManager is wired.
        var sink = NullOpcUaAddressSpaceSink.Instance;
        sink.WriteValue("x", 1, OpcUaQuality.Good, DateTime.UtcNow);
        sink.WriteAlarmState("a", true, false, DateTime.UtcNow);
        sink.RebuildAddressSpace();
        await Task.CompletedTask;
    }

    private async Task<(OpcUaApplicationHost Host, OtOpcUaSdkServer Server)> BootAsync()
    {
        var host = new OpcUaApplicationHost(
            new OpcUaApplicationHostOptions
            {
                ApplicationName = "OtOpcUa.SinkTest",
                ApplicationUri = $"urn:OtOpcUa.SinkTest:{Guid.NewGuid():N}",
                OpcUaPort = AllocateFreePort(),
                PublicHostname = "localhost",
                PkiStoreRoot = _pkiRoot,
            },
            NullLogger<OpcUaApplicationHost>.Instance);

        var server = new OtOpcUaSdkServer();
        await host.StartAsync(server, Ct);
        return (host, server);
    }

    private static int AllocateFreePort()
    {
        using var listener = new System.Net.Sockets.TcpListener(System.Net.IPAddress.Loopback, 0);
        listener.Start();
        var port = ((System.Net.IPEndPoint)listener.LocalEndpoint).Port;
        listener.Stop();
        return port;
    }

    /// <summary>Cleans up the PKI root directory.</summary>
    public void Dispose()
    {
        if (Directory.Exists(_pkiRoot))
        {
            try { Directory.Delete(_pkiRoot, recursive: true); }
            catch { /* best-effort cleanup */ }
        }
    }
}
