/// @file dpf/net/comm_hook.hpp
/// @brief Replaceable transport under trio helpers.
/// @details Protocols call `trio::exchange_with`, `send_to` / `recv_from`,
///          `deal` / `accept_deal`, and `trio::batch`. Those helpers go through
///          a `comm_hook` when one is installed. A null hook keeps the current
///          framed mesh. `channel::send` / `recv` stay the raw bypass.
#ifndef LIBDPF_INCLUDE_DPF_NET_COMM_HOOK_HPP__
#define LIBDPF_INCLUDE_DPF_NET_COMM_HOOK_HPP__

#include <cstddef>
#include <cstdint>
#include <memory>
#include <vector>

#include "dpf/net/channel.hpp"
#include "dpf/net/round_sink.hpp"

namespace dpf
{
namespace net
{

class trio;

/// @brief Byte-level transport for trio helpers and RoundSink factories.
/// @details Overrides replace the mesh without changing protocol call sites.
///          Peer ids are `0..2` (`role` as unsigned). Default implementations
///          in `mesh_comm_hook` match today's `channel` framing.
class comm_hook
{
public:
    virtual ~comm_hook() = default;

    /// @brief One-way send on the link to `peer_id`.
    virtual void send_bytes(trio & net, unsigned peer_id, msg tag,
        const void * data, std::size_t n) = 0;

    /// @brief One-way receive from `peer_id`.
    virtual std::vector<std::uint8_t> recv_bytes(trio & net, unsigned peer_id,
        msg tag) = 0;

    /// @brief Duplex exchange. Lower role id sends first.
    virtual std::vector<std::uint8_t> exchange_bytes(trio & net,
        unsigned peer_id, msg tag, const void * data, std::size_t n) = 0;

    /// @brief Homogeneous vector exchange (one frame each way, same length).
    virtual std::vector<std::uint8_t> exchange_vec_bytes(trio & net,
        unsigned peer_id, msg tag, const void * data, std::size_t nbytes) = 0;

    /// @brief Round-batched peer sink for `count` instances.
    virtual std::unique_ptr<RoundSink> batch(trio & net, std::size_t count,
        std::vector<std::size_t> slot_bytes) = 0;
};

}  // namespace net
}  // namespace dpf

#endif  // LIBDPF_INCLUDE_DPF_NET_COMM_HOOK_HPP__