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

namespace ZB.MOM.WW.OtOpcUa.Driver.OpcUaClient.Tests;

/// <summary>#276 — counters are thread-safe and surface through <c>DriverHealth.Diagnostics</c>.</summary>
[Trait("Category", "Unit")]
public sealed class OpcUaClientDiagnosticsTests
{
    [Fact]
    public void Fresh_snapshot_is_all_zero_with_the_full_key_set()
    {
        var snap = new OpcUaClientDiagnostics().Snapshot();

        snap.Keys.ShouldBe(
        [
            "PublishResponseCount", "NotificationCount", "DataChangeCount", "BadStatusValueCount",
            "PublishErrorCount", "KeepAliveMissCount", "ReconnectAttemptCount", "ReconnectSuccessCount",
            "ReconnectExhaustedCount", "LastReconnectUtcTicks", "ReadCallCount", "ReadFailureCount",
            "WriteCallCount", "WriteFailureCount", "ChunkedRequestCount",
        ], ignoreOrder: true);
        snap.Values.ShouldAllBe(v => v == 0);
    }

    [Fact]
    public void Each_recorder_moves_exactly_its_own_counter()
    {
        var d = new OpcUaClientDiagnostics();
        d.RecordPublishResponse();
        d.RecordNotifications(3);
        d.RecordDataChange(bad: false);
        d.RecordDataChange(bad: true);
        d.RecordPublishError();
        d.RecordKeepAliveMiss();
        d.RecordReconnectAttempt();
        d.RecordReconnectSucceeded();
        d.RecordReconnectExhausted();
        d.RecordRead(failed: true);
        d.RecordWrite(failed: false);
        d.RecordChunkedRequest();

        var s = d.Snapshot();
        s["PublishResponseCount"].ShouldBe(1);
        s["NotificationCount"].ShouldBe(3);
        s["DataChangeCount"].ShouldBe(2);
        s["BadStatusValueCount"].ShouldBe(1);
        s["PublishErrorCount"].ShouldBe(1);
        s["KeepAliveMissCount"].ShouldBe(1);
        s["ReconnectAttemptCount"].ShouldBe(1);
        s["ReconnectSuccessCount"].ShouldBe(1);
        s["ReconnectExhaustedCount"].ShouldBe(1);
        s["LastReconnectUtcTicks"].ShouldBeGreaterThan(0);
        s["ReadCallCount"].ShouldBe(1);
        s["ReadFailureCount"].ShouldBe(1);
        s["WriteCallCount"].ShouldBe(1);
        s["WriteFailureCount"].ShouldBe(0);
        s["ChunkedRequestCount"].ShouldBe(1);
    }

    [Fact]
    public void Concurrent_increments_do_not_lose_updates()
    {
        var d = new OpcUaClientDiagnostics();
        const int threads = 8, each = 5_000;

        Parallel.For(0, threads, _ =>
        {
            for (var i = 0; i < each; i++) { d.RecordDataChange(bad: i % 2 == 0); d.RecordNotifications(2); }
        });

        var s = d.Snapshot();
        s["DataChangeCount"].ShouldBe(threads * each);
        s["BadStatusValueCount"].ShouldBe(threads * each / 2);
        s["NotificationCount"].ShouldBe(threads * each * 2);
    }

    [Fact]
    public void Snapshot_is_a_point_in_time_copy()
    {
        var d = new OpcUaClientDiagnostics();
        var before = d.Snapshot();
        d.RecordKeepAliveMiss();

        before["KeepAliveMissCount"].ShouldBe(0);
        d.Snapshot()["KeepAliveMissCount"].ShouldBe(1);
    }

    [Fact]
    public void GetHealth_carries_the_diagnostics_and_keeps_state_fields()
    {
        using var drv = new OpcUaClientDriver(new OpcUaClientDriverOptions(), "opcua-diag");
        drv.DiagnosticsForTest.RecordKeepAliveMiss();
        drv.DiagnosticsForTest.RecordKeepAliveMiss();

        var h = drv.GetHealth();

        h.State.ShouldBe(DriverState.Unknown);
        h.Diagnostics.ShouldNotBeNull();
        h.Diagnostics!["KeepAliveMissCount"].ShouldBe(2);
    }

    [Fact]
    public void DriverHealth_without_diagnostics_stays_back_compatible()
    {
        var h = new DriverHealth(DriverState.Healthy, null, null);

        h.Diagnostics.ShouldBeNull();
        h.ShouldBe(new DriverHealth(DriverState.Healthy, null, null));
    }
}