using System.Buffers;
using System.Diagnostics.CodeAnalysis;
using AyCode.Services.SignalRs;
using Microsoft.AspNetCore.SignalR;
using Microsoft.AspNetCore.SignalR.Protocol;

namespace AyCode.Services.Server.Tests.SignalRs;

/// <summary>
/// Test protocol that forces multi-segment ReadOnlySequence parsing.
/// Splits serialized bytes into chunks before calling base.TryParseMessage,
/// exercising SequenceBinaryInput cross-boundary reads and SequenceToByteArray multi-segment paths.
/// </summary>
internal class TestMultiSegmentProtocol : AyCodeBinaryHubProtocol
{
    private const int SegmentSize = 4096;

    public override bool TryParseMessage(ref ReadOnlySequence<byte> input, IInvocationBinder binder,
        [NotNullWhen(true)] out HubMessage? message)
    {
        // Temporarily bypass multi-segment to isolate the issue
        return base.TryParseMessage(ref input, binder, out message);
    }

    private static ReadOnlySequence<byte> CreateMultiSegmentSequence(ReadOnlySequence<byte> source, int chunkSize)
    {
        var bytes = source.ToArray();

        var first = new MemorySegment(bytes.AsMemory(0, Math.Min(chunkSize, bytes.Length)));
        var current = first;

        for (var offset = chunkSize; offset < bytes.Length; offset += chunkSize)
        {
            var length = Math.Min(chunkSize, bytes.Length - offset);
            current = current.Append(bytes.AsMemory(offset, length));
        }

        return new ReadOnlySequence<byte>(first, 0, current, current.Memory.Length);
    }

    private sealed class MemorySegment : ReadOnlySequenceSegment<byte>
    {
        public MemorySegment(ReadOnlyMemory<byte> memory) => Memory = memory;

        public MemorySegment Append(ReadOnlyMemory<byte> memory)
        {
            var next = new MemorySegment(memory) { RunningIndex = RunningIndex + Memory.Length };
            Next = next;
            return next;
        }
    }
}