Method runScript

app/src/MQTT/PublisherScriptEditor.cpp:609–704

* @brief Runs mqtt(frame) in a disposable engine and returns the published payload. */

 * @brief Runs mqtt(frame) in a disposable engine and returns the published payload.
 */
QString MQTT::PublisherScriptEditor::runScript(const QString& code,
                                               int language,
                                               const QByteArray& frame,
                                               QString& errorOut)
{
  if (code.trimmed().isEmpty()) {
    errorOut = tr("Script is empty");
    return {};
  }

  if (language == SerialStudio::Lua) {
    lua_State* L = luaL_newstate();
    if (!L) {
      errorOut = tr("Lua engine error");
      return {};
    }

    static const luaL_Reg kSafeLibs[] = {
      {    "_G",   luaopen_base},
      { "table",  luaopen_table},
      {"string", luaopen_string},
      {  "math",   luaopen_math},
      {    "os",     luaopen_os},
      { nullptr,        nullptr}
    };

    for (const luaL_Reg* lib = kSafeLibs; lib->func; ++lib) {
      luaL_requiref(L, lib->name, lib->func, 1);
      lua_pop(L, 1);
    }

    DataModel::installLuaCompat(L);

    const QByteArray utf8 = code.toUtf8();
    if (luaL_dostring(L, utf8.constData()) != LUA_OK) {
      errorOut = tr("Error: %1").arg(QString::fromUtf8(lua_tostring(L, -1)));
      lua_close(L);
      return {};
    }

    lua_getglobal(L, "mqtt");
    if (!lua_isfunction(L, -1)) {
      lua_close(L);
      errorOut = tr("mqtt() is not defined");
      return {};
    }

    lua_pushlstring(L, frame.constData(), static_cast<size_t>(frame.size()));
    if (lua_pcall(L, 1, 1, 0) != LUA_OK) {
      errorOut = tr("Error: %1").arg(QString::fromUtf8(lua_tostring(L, -1)));
      lua_close(L);
      return {};
    }

    QString out;
    if (lua_isstring(L, -1)) {
      size_t len    = 0;
      const char* d = lua_tolstring(L, -1, &len);