std::unique_ptr<Strategy> StrategyFactory::create(const std::string &className) {
  std::map<std::string, std::unique_ptr<Strategy>> strategiesMap;
  strategiesMap.try_emplace("random", unique_ptr<Strategy>(new AlwaysRandom));
  strategiesMap.try_emplace("always_defect", unique_ptr<Strategy>(new AlwaysDefect));
  strategiesMap.try_emplace("always_collude", unique_ptr<Strategy>(new AlwaysCollude));
  strategiesMap.try_emplace("grudger", unique_ptr<Strategy>(new Grudger));
  strategiesMap.try_emplace("copycat", unique_ptr<Strategy>(new CopyCat));
  strategiesMap.try_emplace("detective", unique_ptr<Strategy>(new Detective));
  auto it = strategiesMap.find(className);
  if (it != strategiesMap.end()) {
    return std::move(it->second);
  }
  throw std::runtime_error("no strategy found with this name: " + className);
}