using Shouldly;
using Xunit;

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

/// <summary>
///     R2-07 T4a — <see cref="OtOpcUaNodeManager.MaterialiseAlarmCondition"/> must be idempotent for a
///     same-id + same-kind re-apply: it KEEPS the existing <c>AlarmConditionState</c> instance instead of
///     dropping-and-recreating it. This is what preserves a client's MonitoredItems on an alarm-condition
///     node across a PURE-ADD deploy (the MaterialiseScriptedAlarms pass re-runs over the whole composition
///     every apply, re-touching every existing enabled condition). A genuine kind-swap (native↔scripted)
///     still recreates so the flip takes effect.
/// </summary>
public sealed class NodeManagerAlarmIdempotentMaterialiseTests : IDisposable
{
    private static CancellationToken Ct => TestContext.Current.CancellationToken;

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

    /// <summary>Re-materialising the SAME alarm id + kind returns the SAME instance (reference-equal) — the
    /// condition node is not torn down, so subscriptions on it survive.</summary>
    [Trait("Category", "Unit")]
    [Fact]
    public async Task Re_materialise_same_id_and_kind_keeps_the_same_instance()
    {
        var (host, server) = await BootAsync();
        var nm = server.NodeManager!;
        nm.EnsureFolder("eq-1", parentNodeId: null, displayName: "Equipment 1");

        nm.MaterialiseAlarmCondition("alm-1", "eq-1", "HighTemp", "OffNormalAlarm", 700, isNative: false);
        var first = nm.TryGetAlarmCondition("alm-1");
        first.ShouldNotBeNull();

        // Same id + same kind ⇒ skip-if-present: the existing instance is kept.
        nm.MaterialiseAlarmCondition("alm-1", "eq-1", "HighTemp", "OffNormalAlarm", 700, isNative: false);
        var second = nm.TryGetAlarmCondition("alm-1");

        second.ShouldBeSameAs(first);

        await host.DisposeAsync();
    }

    /// <summary>A kind-swap (scripted → native) on the same id still RECREATES the node so the native flag
    /// flips — the drop-and-recreate is preserved for the kind-swap case.</summary>
    [Trait("Category", "Unit")]
    [Fact]
    public async Task Kind_swap_recreates_and_flips_native_flag()
    {
        var (host, server) = await BootAsync();
        var nm = server.NodeManager!;
        nm.EnsureFolder("eq-1", parentNodeId: null, displayName: "Equipment 1");

        nm.MaterialiseAlarmCondition("alm-1", "eq-1", "HighTemp", "OffNormalAlarm", 700, isNative: false);
        var scripted = nm.TryGetAlarmCondition("alm-1");
        nm.IsNativeAlarmNode("alm-1").ShouldBeFalse();

        // Same id but the OTHER kind ⇒ recreate (a different instance) and the native flag is now set.
        nm.MaterialiseAlarmCondition("alm-1", "eq-1", "HighTemp", "OffNormalAlarm", 700, isNative: true);
        var native = nm.TryGetAlarmCondition("alm-1");

        native.ShouldNotBeSameAs(scripted);
        nm.IsNativeAlarmNode("alm-1").ShouldBeTrue();

        await host.DisposeAsync();
    }

    /// <summary>After a full <see cref="OtOpcUaNodeManager.RebuildAddressSpace"/> cleared the maps, the next
    /// materialise creates a FRESH instance (the skip-if-present guard sees no entry) — so a re-severity
    /// arriving via the rebuild path is reflected.</summary>
    [Trait("Category", "Unit")]
    [Fact]
    public async Task Materialise_after_rebuild_creates_fresh_instance()
    {
        var (host, server) = await BootAsync();
        var nm = server.NodeManager!;
        nm.EnsureFolder("eq-1", parentNodeId: null, displayName: "Equipment 1");

        nm.MaterialiseAlarmCondition("alm-1", "eq-1", "HighTemp", "OffNormalAlarm", 700, isNative: false);
        var before = nm.TryGetAlarmCondition("alm-1");

        nm.RebuildAddressSpace();
        nm.TryGetAlarmCondition("alm-1").ShouldBeNull();

        nm.EnsureFolder("eq-1", parentNodeId: null, displayName: "Equipment 1");
        nm.MaterialiseAlarmCondition("alm-1", "eq-1", "HighTemp", "OffNormalAlarm", 700, isNative: false);
        var after = nm.TryGetAlarmCondition("alm-1");

        after.ShouldNotBeNull();
        after.ShouldNotBeSameAs(before);

        await host.DisposeAsync();
    }

    private async Task<(OpcUaApplicationHost Host, OtOpcUaSdkServer Server)> BootAsync()
    {
        var host = new OpcUaApplicationHost(
            new OpcUaApplicationHostOptions
            {
                ApplicationName = "OtOpcUa.AlarmIdempotentTest",
                ApplicationUri = $"urn:OtOpcUa.AlarmIdempotentTest:{Guid.NewGuid():N}",
                OpcUaPort = AllocateFreePort(),
                PublicHostname = "localhost",
                PkiStoreRoot = _pkiRoot,
            },
            Microsoft.Extensions.Logging.Abstractions.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 */ }
        }
    }
}