using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.AdminUI.Hubs;
using ZB.MOM.WW.OtOpcUa.Commons.Messages.Drivers;

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

/// <summary>
///     Covers the in-process push contract the Blazor Server <c>DriverStatusPanel</c> relies on:
///     <see cref="IDriverStatusSnapshotStore.SnapshotChanged"/> fires on every
///     <see cref="IDriverStatusSnapshotStore.Upsert"/>, and <c>TryGet</c> returns the latest.
///     The panel subscribes to this store directly instead of opening a self-targeted SignalR
///     connection (which a server-side component can't reach behind a reverse proxy).
/// </summary>
public sealed class DriverStatusSnapshotStoreTests
{
    private static DriverHealthChanged Snap(string instance, string state = "Healthy") =>
        new("MAIN", instance, state, null, null, 0, new DateTime(2026, 5, 29, 0, 0, 0, DateTimeKind.Utc));

    [Fact]
    public void Upsert_raises_SnapshotChanged_with_the_stored_snapshot()
    {
        var store = new InMemoryDriverStatusSnapshotStore();
        var received = new List<DriverHealthChanged>();
        store.SnapshotChanged += received.Add;

        var snap = Snap("drv-1", "Faulted");
        store.Upsert(snap);

        received.Count.ShouldBe(1);
        received[0].ShouldBeSameAs(snap);
    }

    [Fact]
    public void Upsert_then_TryGet_returns_the_latest_snapshot()
    {
        var store = new InMemoryDriverStatusSnapshotStore();
        store.Upsert(Snap("drv-1", "Healthy"));
        store.Upsert(Snap("drv-1", "Degraded"));

        store.TryGet("drv-1", out var latest).ShouldBeTrue();
        latest.State.ShouldBe("Degraded");
    }

    [Fact]
    public void Unsubscribed_handler_stops_receiving_after_removal()
    {
        var store = new InMemoryDriverStatusSnapshotStore();
        var count = 0;
        void Handler(DriverHealthChanged _) => count++;

        store.SnapshotChanged += Handler;
        store.Upsert(Snap("drv-1"));
        store.SnapshotChanged -= Handler;
        store.Upsert(Snap("drv-1"));

        count.ShouldBe(1);
    }

    [Fact]
    public void Snapshots_from_two_nodes_for_one_driver_are_kept_side_by_side_847()
    {
        var store = new InMemoryDriverStatusSnapshotStore();
        var t0 = new DateTime(2026, 11, 11, 0, 0, 0, DateTimeKind.Utc);
        store.Upsert(new DriverHealthChanged("MAIN", "drv", "Faulted", null, "x", 1, t0, ReportingNodeId: "central-1"));
        store.Upsert(new DriverHealthChanged("MAIN", "drv", "Healthy", null, null, 0, t0.AddSeconds(1), ReportingNodeId: "central-2"));
        // A re-publish from central-1 replaces only central-1's entry.
        store.Upsert(new DriverHealthChanged("MAIN", "drv", "Faulted", null, "y", 2, t0.AddSeconds(2), ReportingNodeId: "central-1"));

        var all = store.GetAll();
        all.Count.ShouldBe(2);
        all.Single(s => s.ReportingNodeId == "central-1").LastError.ShouldBe("y");
        all.Single(s => s.ReportingNodeId == "central-2").State.ShouldBe("Healthy");

        // TryGet (the per-driver panel / hub) answers the most recently published across nodes.
        store.TryGet("drv", out var latest).ShouldBeTrue();
        latest.ReportingNodeId.ShouldBe("central-1");
        latest.LastError.ShouldBe("y");
        store.TryGet("other", out _).ShouldBeFalse();
    }

    [Fact]
    public void Eviction_removes_every_node_entry_of_an_unconfigured_stale_driver_847()
    {
        var store = new InMemoryDriverStatusSnapshotStore();
        var old = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
        store.Upsert(new DriverHealthChanged("MAIN", "gone", "Healthy", null, null, 0, old, ReportingNodeId: "a"));
        store.Upsert(new DriverHealthChanged("MAIN", "gone", "Healthy", null, null, 0, old, ReportingNodeId: "b"));
        store.Upsert(new DriverHealthChanged("MAIN", "kept", "Healthy", null, null, 0, old, ReportingNodeId: "a"));

        store.EvictUnconfiguredStale(new HashSet<string> { "kept" }, old.AddMinutes(1)).ShouldBe(2);
        store.GetAll().ShouldHaveSingleItem().DriverInstanceId.ShouldBe("kept");
    }
}