#pragma once

#include <cstdint>
#include <optional>
#include <string>
#include <vector>

#include "secsgem/secs2/codec.hpp"
#include "secsgem/secs2/item.hpp"

namespace secsgem::secs2 {

// A logical SECS-II message: stream/function, the W-bit (reply expected), and
// an optional root data item as the body. The transport (HSMS) header carries
// stream/function/W on the wire; the body bytes are the encoded root item.
struct Message {
  uint8_t stream = 0;
  uint8_t function = 0;
  bool reply_expected = false;  // W-bit
  std::optional<Item> body;

  Message() = default;
  Message(uint8_t s, uint8_t f, bool w, std::optional<Item> b = std::nullopt)
      : stream(s), function(f), reply_expected(w), body(std::move(b)) {}

  std::vector<uint8_t> encode_body() const {
    if (!body) return {};
    return encode(*body);
  }

  static Message from_body(uint8_t stream, uint8_t function, bool reply_expected,
                           const std::vector<uint8_t>& body_bytes) {
    Message m(stream, function, reply_expected);
    if (!body_bytes.empty()) m.body = decode(body_bytes);
    return m;
  }

  // e.g.  S1F2
  //         <L [2] <A "MDLN"> <A "1.0"> > .
  std::string sml() const {
    std::string out = "S" + std::to_string(stream) + "F" + std::to_string(function);
    if (reply_expected) out += " W";
    if (body) {
      out += "\n  ";
      out += to_sml(*body);
    }
    out += " .";
    return out;
  }
};

}  // namespace secsgem::secs2