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

namespace ZB.MOM.WW.OtOpcUa.Driver.S7.Tests;

/// <summary>
///     Shape tests for <see cref="S7Driver"/>'s <see cref="ITagDiscovery"/>,
///     <see cref="ISubscribable"/>, and <see cref="IHostConnectivityProbe"/> surfaces that
///     don't need a live PLC. Wire-level polling round-trips and probe transitions land in a
///     follow-up PR once we have a mock S7 server.
/// </summary>
[Trait("Category", "Unit")]
public sealed class S7DiscoveryAndSubscribeTests
{
    private sealed class RecordingAddressSpaceBuilder : IAddressSpaceBuilder
    {
        public readonly List<string> Folders = new();
        public readonly List<(string Name, DriverAttributeInfo Attr)> Variables = new();

        public IAddressSpaceBuilder Folder(string browseName, string displayName)
        {
            Folders.Add(browseName);
            return this;
        }
        public IVariableHandle Variable(string browseName, string displayName, DriverAttributeInfo attributeInfo)
        {
            Variables.Add((browseName, attributeInfo));
            return new StubHandle();
        }
        public void AddProperty(string browseName, DriverDataType dataType, object? value) { }
        public void AttachAlarmCondition(IVariableHandle sourceVariable, string alarmName, DriverAttributeInfo alarmInfo) { }

        private sealed class StubHandle : IVariableHandle
        {
            public string FullReference => "stub";
            public IAlarmConditionSink MarkAsAlarmCondition(AlarmConditionInfo info)
                => throw new NotImplementedException("S7 driver never calls this — no alarm surfacing");
        }
    }

    [Fact]
    public async Task DiscoverAsync_projects_every_tag_into_the_address_space()
    {
        var opts = new S7DriverOptions
        {
            Host = "192.0.2.1",
            Tags =
            [
                new("TempSetpoint", "DB1.DBW0", S7DataType.Int16, Writable: true),
                new("FaultBit", "M0.0", S7DataType.Bool, Writable: false),
                new("PIDOutput", "DB5.DBD12", S7DataType.Float32, Writable: true),
            ],
        };
        using var drv = new S7Driver(opts, "s7-disco");

        var builder = new RecordingAddressSpaceBuilder();
        await drv.DiscoverAsync(builder, TestContext.Current.CancellationToken);

        builder.Folders.ShouldContain("S7");
        builder.Variables.Count.ShouldBe(3);
        builder.Variables[0].Name.ShouldBe("TempSetpoint");
        builder.Variables[0].Attr.SecurityClass.ShouldBe(SecurityClassification.Operate, "writable tags get Operate security class");
        builder.Variables[1].Attr.SecurityClass.ShouldBe(SecurityClassification.ViewOnly, "read-only tags get ViewOnly");
        builder.Variables[2].Attr.DriverDataType.ShouldBe(DriverDataType.Float32);
    }

    [Fact]
    public async Task DiscoverAsync_propagates_WriteIdempotent_from_tag_to_attribute_info()
    {
        var opts = new S7DriverOptions
        {
            Host = "192.0.2.1",
            Tags =
            [
                new("SetPoint", "DB1.DBW0", S7DataType.Int16, WriteIdempotent: true),
                new("StartBit", "M0.0", S7DataType.Bool),
            ],
        };
        using var drv = new S7Driver(opts, "s7-idem");

        var builder = new RecordingAddressSpaceBuilder();
        await drv.DiscoverAsync(builder, TestContext.Current.CancellationToken);

        builder.Variables.Single(v => v.Name == "SetPoint").Attr.WriteIdempotent.ShouldBeTrue();
        builder.Variables.Single(v => v.Name == "StartBit").Attr.WriteIdempotent.ShouldBeFalse("default is opt-in per decision #44");
    }

    [Fact]
    public void GetHostStatuses_returns_one_row_with_host_port_identity_pre_init()
    {
        var opts = new S7DriverOptions { Host = "plc1.internal", Port = 102 };
        using var drv = new S7Driver(opts, "s7-host");

        var rows = drv.GetHostStatuses();
        rows.Count.ShouldBe(1);
        rows[0].HostName.ShouldBe("plc1.internal:102");
        rows[0].State.ShouldBe(HostState.Unknown, "pre-init / pre-probe state is Unknown");
    }

    [Fact]
    public async Task SubscribeAsync_returns_unique_handles_and_UnsubscribeAsync_accepts_them()
    {
        var opts = new S7DriverOptions { Host = "192.0.2.1" };
        using var drv = new S7Driver(opts, "s7-sub");

        // SubscribeAsync does not itself call ReadAsync (the poll task does), so this works
        // even though the driver isn't initialized. The poll task catches the resulting
        // InvalidOperationException and the loop quietly continues — same pattern as the
        // Modbus driver's poll loop tolerating transient transport failures.
        var h1 = await drv.SubscribeAsync(["T1"], TimeSpan.FromMilliseconds(200), TestContext.Current.CancellationToken);
        var h2 = await drv.SubscribeAsync(["T2"], TimeSpan.FromMilliseconds(200), TestContext.Current.CancellationToken);

        h1.DiagnosticId.ShouldStartWith("s7-sub-");
        h2.DiagnosticId.ShouldStartWith("s7-sub-");
        h1.DiagnosticId.ShouldNotBe(h2.DiagnosticId);

        await drv.UnsubscribeAsync(h1, TestContext.Current.CancellationToken);
        await drv.UnsubscribeAsync(h2, TestContext.Current.CancellationToken);
        // UnsubscribeAsync with an unknown handle must be a no-op, not throw.
        await drv.UnsubscribeAsync(h1, TestContext.Current.CancellationToken);
    }

    [Fact]
    public async Task Subscribe_publishing_interval_is_floored_at_100ms()
    {
        var opts = new S7DriverOptions { Host = "192.0.2.1", Probe = new S7ProbeOptions { Enabled = false } };
        using var drv = new S7Driver(opts, "s7-floor");

        // 50 ms requested — the floor protects the S7 CPU from sub-scan polling that would
        // just queue wire-side. Test that the subscription is accepted (the floor is applied
        // internally; the floor value isn't exposed, so we're really just asserting that the
        // driver doesn't reject small intervals).
        var h = await drv.SubscribeAsync(["T"], TimeSpan.FromMilliseconds(50), TestContext.Current.CancellationToken);
        h.ShouldNotBeNull();
        await drv.UnsubscribeAsync(h, TestContext.Current.CancellationToken);
    }
}