using System.Buffers.Binary;
using Shouldly;
using Xunit;

namespace ZB.MOM.WW.OtOpcUa.Driver.Ab.Transport.Tests.Captures;

public sealed class CaptureFileTests
{
    private static readonly string[] Required =
    [
        "logix-register-session.hex", "logix-forward-open.hex",
        "logix-read-dint.hex", "logix-read-dint-array16.hex", "logix-read-string.hex", "logix-read-bool.hex",
        "logix-write-dint.hex", "logix-write-string.hex", "logix-read-unknown-tag.hex",
        "logix-tags-listing.hex", "logix-forward-close.hex", "micro800-read-dint.hex",
        "slc500-read-n7.hex", "slc500-write-n7.hex", "slc500-read-f8.hex",
        "micrologix-read-n7.hex", "plc5-read-n7.hex",
    ];

    public static TheoryData<string> AllCaptures()
    {
        var data = new TheoryData<string>();
        foreach (var f in Directory.GetFiles(CaptureFile.Dir, "*.hex").Order()) data.Add(Path.GetFileName(f));
        return data;
    }

    [Fact]
    public void Every_required_capture_is_present() =>
        Required.Where(n => !File.Exists(Path.Combine(CaptureFile.Dir, n))).ShouldBeEmpty();

    [Theory]
    [MemberData(nameof(AllCaptures))]
    public void Every_frame_length_field_matches_its_data_length(string name)
    {
        var frames = CaptureFile.Load(name);

        frames.ShouldNotBeEmpty();
        foreach (var f in frames)
        {
            f.Bytes.Length.ShouldBeGreaterThanOrEqualTo(24, name);
            BinaryPrimitives.ReadUInt16LittleEndian(f.Bytes.AsSpan(2)).ShouldBe((ushort)(f.Bytes.Length - 24), name);
        }
    }

    [Theory]
    [MemberData(nameof(AllCaptures))]
    public void Frames_alternate_request_then_reply(string name)
    {
        var frames = CaptureFile.Load(name);

        frames.Count.ShouldBe(frames.Count / 2 * 2, name);
        for (var i = 0; i < frames.Count; i++) frames[i].FromClient.ShouldBe(i % 2 == 0, $"{name} frame {i}");
    }

    [Theory]
    [MemberData(nameof(AllCaptures))]
    public void Every_CPF_item_walk_ends_exactly_at_the_frame_end(string name)
    {
        foreach (var f in CaptureFile.Load(name).Where(f => BinaryPrimitives.ReadUInt16LittleEndian(f.Bytes.AsSpan(0)) is 0x6F or 0x70))
        {
            var pos = 24 + 4 + 2;
            var itemCount = BinaryPrimitives.ReadUInt16LittleEndian(f.Bytes.AsSpan(pos));
            pos += 2;
            for (var i = 0; i < itemCount; i++) pos += 4 + BinaryPrimitives.ReadUInt16LittleEndian(f.Bytes.AsSpan(pos + 2));

            pos.ShouldBe(f.Bytes.Length, name);
        }
    }

    [Theory]
    [MemberData(nameof(AllCaptures))]
    public void Every_reply_service_is_its_request_service_with_the_reply_bit(string name)
    {
        var frames = CaptureFile.Load(name);
        for (var i = 0; i + 1 < frames.Count; i += 2)
        {
            var request = CaptureFile.CipPayload(frames[i]);
            var reply = CaptureFile.CipPayload(frames[i + 1]);
            if (request.Length == 0) continue;   // RegisterSession: no CIP

            reply[0].ShouldBe((byte)(request[0] | 0x80), $"{name} pair {i / 2}");
        }
    }

    [Fact]
    public void CipPayload_strips_the_connected_sequence_count()
    {
        // Connected Read Tag Fragmented of TestDINT: service 0x52, path size 5 words, symbol 0x91 len 8.
        var request = CaptureFile.Load("logix-read-dint.hex")[0];

        CaptureFile.CipPayload(request)[..4].ShouldBe(new byte[] { 0x52, 0x05, 0x91, 0x08 });
    }

    [Fact]
    public void CipPayload_returns_the_unconnected_item_for_SendRRData()
    {
        // Large Forward Open request goes out in an unconnected data item (0xB2): service 0x5B.
        var request = CaptureFile.Load("logix-forward-open.hex")[0];

        CaptureFile.CipPayload(request)[0].ShouldBe((byte)0x5B);
    }

    [Fact]
    public void CipPayload_is_empty_for_RegisterSession() =>
        CaptureFile.CipPayload(CaptureFile.Load("logix-register-session.hex")[0]).ShouldBeEmpty();
}