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

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

/// <summary>
///     Review 07 H17: Logix allows a <c>.n</c> bit selector on SINT / INT / DINT (and LINT) hosts, and reads of
///     <c>Flags.3</c> on an INT worked — but the bit write's read-modify-write hard-coded a DINT parent, so its
///     <c>DecodeValue(DInt)</c> on a 2-byte buffer threw OutOfBounds and the write was reported as a comms fault
///     (BadCommunicationError + Degraded). The parent width now comes from the parent read's size.
/// </summary>
[Trait("Category", "Unit")]
public sealed class AbCipBitInWordWidthTests
{
    private const string Device = "ab://10.0.0.5/1,0";

    private static async Task<(AbCipDriver Driver, FakeAbCipTagFactory Factory)> BuildAsync(int parentSize, object parentValue, string bitPath)
    {
        var factory = new FakeAbCipTagFactory
        {
            Customise = p => new FakeAbCipTag(p) { Value = parentValue, Size = parentSize },
        };
        var drv = new AbCipDriver(new AbCipDriverOptions
        {
            Devices = [new AbCipDeviceOptions(Device)],
            RawTags = AbCipRawTags.From(new AbCipTagDefinition("Bit", Device, bitPath, AbCipDataType.Bool)),
            Probe = new AbCipProbeOptions { Enabled = false },
        }, "abcip-bit", factory);
        await drv.InitializeAsync("{}", CancellationToken.None);
        return (drv, factory);
    }

    /// <summary>SINT / INT / DINT hosts: the bit is set, every other bit is preserved, nothing degrades.</summary>
    /// <param name="size">The parent's wire width.</param>
    /// <param name="before">The parent's value before the write.</param>
    /// <param name="bit">The bit written true.</param>
    /// <param name="after">The value the parent must be written back with.</param>
    [Theory]
    [InlineData(1, 0x81, 3, 0x89)]       // SINT 0x81 (-127): bit 7 set stays set, written as its unsigned byte
    [InlineData(1, 0x00, 7, 0x80)]       // SINT top bit: 128 would overflow an sbyte encode
    [InlineData(2, 0x8001, 3, 0x8009)]   // INT top bit preserved
    [InlineData(2, 0x0000, 15, 0x8000)]  // INT top bit: 32768 would overflow a short encode
    [InlineData(4, 0x00000001, 3, 0x00000009)]
    public async Task A_bit_write_uses_the_parent_width(int size, int before, int bit, int after)
    {
        var (drv, factory) = await BuildAsync(size, before, $"Motor.Flags.{bit}");

        var r = await drv.WriteAsync([new WriteRequest("Bit", true)], CancellationToken.None);

        r[0].StatusCode.ShouldBe(AbCipStatusMapper.Good);
        Convert.ToInt64(factory.Tags["Motor.Flags"].Value).ShouldBe(after);
        factory.Tags["Motor.Flags"].WriteCount.ShouldBe(1);
        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
    }

    /// <summary>A bit past the host's width is refused before anything is written, with no health write.</summary>
    [Fact]
    public async Task A_bit_past_the_host_width_is_BadOutOfRange_and_nothing_is_written()
    {
        var (drv, factory) = await BuildAsync(2, 0, "Motor.Flags.20");

        var r = await drv.WriteAsync([new WriteRequest("Bit", true)], CancellationToken.None);

        r[0].StatusCode.ShouldBe(AbCipStatusMapper.BadOutOfRange);
        factory.Tags["Motor.Flags"].WriteCount.ShouldBe(0);
        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
    }

    /// <summary>A host whose width is no integer's is a type mismatch, refused before writing, no health write.</summary>
    [Fact]
    public async Task A_host_of_no_integer_width_is_BadTypeMismatch()
    {
        var (drv, factory) = await BuildAsync(3, 0, "Motor.Flags.1");

        var r = await drv.WriteAsync([new WriteRequest("Bit", true)], CancellationToken.None);

        r[0].StatusCode.ShouldBe(AbCipStatusMapper.BadTypeMismatch);
        factory.Tags["Motor.Flags"].WriteCount.ShouldBe(0);
        drv.GetHealth().State.ShouldBe(DriverState.Healthy);
    }

    /// <summary>
    ///     End to end over the REAL native runtime against a fake CIP target whose <c>Flags</c> is an INT: the write
    ///     goes out as ONE INT (type 0xC3, two data bytes) with the bit set and the other bits preserved.
    /// </summary>
    [Fact]
    public async Task A_native_bit_write_on_an_INT_host_writes_an_INT()
    {
        await using var target = new FakeCipTarget();
        // Read Tag Fragmented (0x52) → INT (0x00C3) 0x8001; Write Tag (0x4D) → success.
        target.ConnectedHandler = req => Task.FromResult<byte[]?>(req[0] switch
        {
            0x52 => [0xD2, 0x00, 0x00, 0x00, 0xC3, 0x00, 0x01, 0x80],
            0x4D => [0xCD, 0x00, 0x00, 0x00],
            _ => target.ServiceReply(req),
        });
        var host = $"ab://127.0.0.1:{target.Port}/1,0";
        var drv = new AbCipDriver(new AbCipDriverOptions
        {
            Devices = [new AbCipDeviceOptions(host, AbCipPlcFamily.ControlLogix)],
            RawTags = AbCipRawTags.From(new AbCipTagDefinition("Bit", host, "Flags.3", AbCipDataType.Bool)),
            Probe = new AbCipProbeOptions { Enabled = false },
            Timeout = TimeSpan.FromSeconds(5),
        }, "abcip-bit-native", new NativeAbCipTagFactory(new DeviceSessionPool()));
        await drv.InitializeAsync("{}", CancellationToken.None);
        try
        {
            var r = await drv.WriteAsync([new WriteRequest("Bit", true)], CancellationToken.None);

            r[0].StatusCode.ShouldBe(AbCipStatusMapper.Good);
            var write = target.ConnectedCips.Single(c => c[0] == 0x4D);
            var typeAt = 2 + write[1] * 2;
            write[typeAt].ShouldBe((byte)0xC3);                 // INT, not DINT
            write.Length.ShouldBe(typeAt + 2 + 2 + 2);          // type, element count, ONE 2-byte element
            write[^2].ShouldBe((byte)0x09);                     // 0x8001 | bit 3
            write[^1].ShouldBe((byte)0x80);
            drv.GetHealth().State.ShouldBe(DriverState.Healthy);
        }
        finally
        {
            await drv.DisposeAsync();
        }
    }
}