using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.PlcFamilies;
using ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport;
using ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport.Tests.Fakes;

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

/// <summary>
///     Lane K F3 (AbLegacy F8, review 07 r0 I4), end to end over a real socket with the PRODUCTION
///     <see cref="NativeAbLegacyTagFactory"/>: a bridge (DHRIO / 1761-NET-ENI) in front of a dead DH+ node answers every
///     PCCC request with STS 0x30 "remote node host missing". That is NOT the device answering, so the driver must treat
///     it as a comms fault — Degraded, <c>LastSuccessfulRead</c> not advanced — or the comms-loss watchdog never fires
///     for it. The positive control is a live device refusing a tag (STS 0x60, command protection): per-tag Bad, Healthy,
///     <c>LastSuccessfulRead</c> advanced.
/// </summary>
[Trait("Category", "Unit")]
public sealed class NativePcccBridgeStatusHealthTests
{
    private static readonly byte[] FixedId = [0x07, 0x3D, 0xF3, 0x45, 0x43, 0x50, 0x21];

    /// <summary>A fake whose Execute PCCC envelope itself is refused with CIP general status <paramref name="general"/>.</summary>
    private static FakeEipServer CipEnvelopeServer(byte general)
    {
        var server = new FakeEipServer { ZeroReplyContext = true };
        server.Handler = req => FakeEipServer.Command(req) == Ab.Transport.Eip.EncapCommand.SendRRData
            ? FakeEipServer.RRReply(req, [0xCB, 0x00, general, 0x00])
            : null;
        return server;
    }

    /// <summary>A PCCC fake that answers every request with one fixed STS.</summary>
    private static FakeEipServer StsServer(byte sts)
    {
        var server = new FakeEipServer { ZeroReplyContext = true };
        server.Handler = req =>
        {
            if (FakeEipServer.Command(req) != Ab.Transport.Eip.EncapCommand.SendRRData) return null;
            var cip = FakeEipServer.RequestCip(req);
            byte[] head = [0xCB, 0x00, 0x00, 0x00, .. FixedId, 0x4F];
            return FakeEipServer.RRReply(req, [.. head, sts, cip[15], cip[16]]);
        };
        return server;
    }

    /// <summary>
    ///     A manual clock the driver stamps health from (lmxopcua#768). Init stamps <see cref="InitTime"/>; each test
    ///     moves it to <see cref="ReadTime"/> before reading, so an "advanced" <c>LastSuccessfulRead</c> is provably
    ///     the read's stamp (it used to be <c>DateTime.UtcNow</c> twice microseconds apart, equal ~70% of runs on a
    ///     coarse clock, lmxopcua#767).
    /// </summary>
    private static readonly DateTime InitTime = new(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);

    private static readonly DateTime ReadTime = InitTime.AddSeconds(1);

#pragma warning disable OTOPCUA0001 // the driver is called directly to pin its OWN classification (no resilience wrap)
    private static async Task<AbLegacyDriver> DriverAsync(FakeEipServer server, Func<DateTime> clock)
    {
        var host = $"ab://127.0.0.1:{server.Port}/1,0";
        var driver = new AbLegacyDriver(new AbLegacyDriverOptions
        {
            Devices = [new AbLegacyDeviceOptions(host, AbLegacyPlcFamily.Slc500)],
            RawTags = AbLegacyRawTags.Entries([new AbLegacyTagDefinition("T", host, "N7:0", AbLegacyDataType.Int)]),
            Timeout = TimeSpan.FromSeconds(5),
            Probe = new AbLegacyProbeOptions { Enabled = false },
        }, "drv-pccc-bridge", new NativeAbLegacyTagFactory(new DeviceSessionPool()))
        {
            Clock = clock,
        };
        await driver.InitializeAsync("{}", TestContext.Current.CancellationToken);
        return driver;
    }

    /// <summary>STS 0x30 from a bridge: a comms fault, never evidence the device answered.</summary>
    [Fact]
    public async Task A_dead_node_behind_a_bridge_degrades_and_does_not_advance_LastSuccessfulRead()
    {
        var ct = TestContext.Current.CancellationToken;
        await using var server = StsServer(0x30);
        var now = InitTime;
        var driver = await DriverAsync(server, () => now);
        var before = driver.GetHealth().LastSuccessfulRead;
        before.ShouldBe(InitTime);
        now = ReadTime;

        var result = (await driver.ReadAsync(["T"], ct)).Single();

        result.StatusCode.ShouldBe(AbLegacyStatusMapper.BadCommunicationError);
        var health = driver.GetHealth();
        health.State.ShouldBe(DriverState.Degraded);
        health.LastSuccessfulRead.ShouldBe(before);
        await driver.ShutdownAsync(ct);
        server.HandlerErrors.ShouldBeEmpty();
    }

    /// <summary>Positive control: STS 0x60 is the live device refusing the tag — answered, so Healthy and advanced.</summary>
    [Fact]
    public async Task A_live_device_refusing_the_tag_stays_Healthy_and_advances_LastSuccessfulRead()
    {
        var ct = TestContext.Current.CancellationToken;
        await using var server = StsServer(0x60);
        var now = InitTime;
        var driver = await DriverAsync(server, () => now);
        var before = driver.GetHealth().LastSuccessfulRead;
        before.ShouldBe(InitTime);
        now = ReadTime;

        var result = (await driver.ReadAsync(["T"], ct)).Single();

        result.StatusCode.ShouldBe(AbOpcUaStatusMap.BadNotWritable);
        var health = driver.GetHealth();
        health.State.ShouldBe(DriverState.Healthy);
        health.LastSuccessfulRead.ShouldBe(ReadTime);
        await driver.ShutdownAsync(ct);
        server.HandlerErrors.ShouldBeEmpty();
    }

    /// <summary>
    ///     Review I2: a refusal that came OFF THE WIRE — the device (or the bridge's Execute PCCC object) answered with
    ///     CIP 0x08 / 0x1C / 0x20 on the envelope, or PCCC STS 0x10 — is an answered refusal: per-tag BadNotSupported,
    ///     Healthy, <c>LastSuccessfulRead</c> advanced. It must not land in the "refused before the wire" neutral class
    ///     (which advances nothing). The local-refusal counterpart stays neutral (NativeAbLegacyRefusedWriteTests).
    /// </summary>
    /// <param name="general">The CIP general status of the envelope reply, or 0 for a PCCC STS 0x10 reply.</param>
    [Theory]
    [InlineData((byte)0x08)]
    [InlineData((byte)0x1C)]
    [InlineData((byte)0x20)]
    [InlineData((byte)0x00)]
    public async Task A_wire_Unsupported_reply_is_an_answered_refusal(byte general)
    {
        var ct = TestContext.Current.CancellationToken;
        await using var server = general == 0 ? StsServer(0x10) : CipEnvelopeServer(general);
        var now = InitTime;
        var driver = await DriverAsync(server, () => now);
        var before = driver.GetHealth().LastSuccessfulRead;
        before.ShouldBe(InitTime);
        now = ReadTime;

        var result = (await driver.ReadAsync(["T"], ct)).Single();

        result.StatusCode.ShouldBe(AbLegacyStatusMapper.BadNotSupported);
        var health = driver.GetHealth();
        health.State.ShouldBe(DriverState.Healthy);
        health.LastSuccessfulRead.ShouldBe(ReadTime);
        await driver.ShutdownAsync(ct);
        server.HandlerErrors.ShouldBeEmpty();
    }
#pragma warning restore OTOPCUA0001
}