#pragma once

#include <algorithm>
#include <array>
#include <cstdint>
#include <optional>
#include <span>

#include "wireframe/byteio.hpp"

namespace wireframe::net {

inline constexpr std::size_t kEthernetHeaderLen = 14;
inline constexpr std::uint16_t kEthertypeIPv4 = 0x0800;
inline constexpr std::uint16_t kEthertypeIPv6 = 0x86DD;
inline constexpr std::uint16_t kEthertypeArp = 0x0806;

struct MacAddress {
    std::array<unsigned char, 6> bytes;
};

struct EthernetHeader {
    MacAddress dst;
    MacAddress src;
    std::uint16_t ethertype;
};

struct EthernetFrame {
    EthernetHeader header;
    std::span<const unsigned char> payload;
};

inline std::optional<EthernetFrame> parse_ethernet(std::span<const unsigned char> bytes) {
    if (bytes.size() < kEthernetHeaderLen) return std::nullopt;

    EthernetHeader header{};
    std::copy_n(bytes.begin(), 6, header.dst.bytes.begin());
    std::copy_n(bytes.begin() + 6, 6, header.src.bytes.begin());
    header.ethertype = read_be16(bytes, 12);

    return EthernetFrame{header, bytes.subspan(kEthernetHeaderLen)};
}

}  // namespace wireframe::net