using AyCode.Core.Serializers;
using AyCode.Core.Tests.TestModels;
using MemoryPack;
using System.Buffers;
using System.Runtime.CompilerServices;

namespace AyCode.Core.Benchmarks.Workloads.Scenarios;

/// <summary>
/// Benchmarks MemoryPack via the IBufferWriter overload, allocating a FRESH ArrayBufferWriter on EVERY call.
/// Apples-to-apples counterpart to <see cref="AcBinaryFreshBufferWriterBenchmark{T}"/>.
/// </summary>
public sealed class MemoryPackFreshBufferWriterBenchmark<T> : ISerializerBenchmark where T : class
{
    private readonly T _order;
    private readonly MemoryPackSerializerOptions _options;
    private readonly byte[] _serialized;

    public BenchmarkEngine Engine => BenchmarkEngine.MemoryPack;
    public BenchmarkIoMode IoMode => BenchmarkIoMode.BufWrNew;
    public BenchmarkDispatchMode DispatchMode => BenchmarkDispatchMode.SGen; // MemoryPack always uses [MemoryPackable] source-generated formatters
    public Type OrderType => typeof(T);
    public string OptionsPreset { get; }
    public int SerializedSize => _serialized.Length;
    public long SetupSerializeAllocBytes => 0;
    public long SetupDeserializeAllocBytes => 0;
    public string? OptionsDescription => $"StringEncoding={_options.StringEncoding}";

    public MemoryPackFreshBufferWriterBenchmark(T order, WireMode wireMode, string optionsPreset)
    {
        _order = order;
        OptionsPreset = optionsPreset;
        _options = BenchmarkOptions.GetMemPack(wireMode);
        _serialized = MemoryPackSerializer.Serialize(order, _options);
    }

    [MethodImpl(MethodImplOptions.NoInlining)]
    public void Serialize()
    {
        var abw = new ArrayBufferWriter<byte>();
        MemoryPackSerializer.Serialize(abw, _order, _options);
    }

    // BufWr semantic: read from a ReadOnlySequence<byte> overload (apples-to-apples with AcBinary's
    // BufWr Deser path). MemoryPack's ROS overload also single-segment-fast-paths internally.
    [MethodImpl(MethodImplOptions.NoInlining)]
    public void Deserialize() => MemoryPackSerializer.Deserialize<T>(new ReadOnlySequence<byte>(_serialized), _options);

    public bool VerifyRoundTrip()
    {
        var abw = new ArrayBufferWriter<byte>();
        MemoryPackSerializer.Serialize(abw, _order, _options);
        var roundTripped = MemoryPackSerializer.Deserialize<T>(new ReadOnlySequence<byte>(abw.WrittenMemory), _options);
        return RoundTripValidator.DeepEqualsViaJson(_order, roundTripped);
    }
}
