the-biergarten-app/pipeline/src/wikipedia/wikipedia_service.cpp

#include "wikipedia/wikipedia_service.h"
#include <boost/json.hpp>
#include <spdlog/spdlog.h>

WikipediaService::WikipediaService(std::shared_ptr<WebClient> client)
    : client_(std::move(client)) {}

std::string WikipediaService::FetchExtract(std::string_view query) {
  const std::string encoded = client_->UrlEncode(std::string(query));
  const std::string url =
      "https://en.wikipedia.org/w/api.php?action=query&titles=" + encoded +
      "&prop=extracts&explaintext=true&format=json";

  const std::string body = client_->Get(url);

  boost::system::error_code ec;
  boost::json::value doc = boost::json::parse(body, ec);

  if (!ec && doc.is_object()) {
    auto &pages = doc.at("query").at("pages").get_object();
    if (!pages.empty()) {
      auto &page = pages.begin()->value().get_object();
      if (page.contains("extract") && page.at("extract").is_string()) {
        std::string extract(page.at("extract").as_string().c_str());
        spdlog::debug("WikipediaService fetched {} chars for '{}'",
                      extract.size(), query);
        return extract;
      }
    }
  }

  return {};
}

std::string WikipediaService::GetSummary(std::string_view city,
                                         std::string_view country) {
  const std::string key = std::string(city) + "|" + std::string(country);
  const auto cacheIt = cache_.find(key);
  if (cacheIt != cache_.end()) {
    return cacheIt->second;
  }

  std::string result;

  if (!client_) {
    cache_.emplace(key, result);
    return result;
  }

  std::string regionQuery(city);
  if (!country.empty()) {
    regionQuery += ", ";
    regionQuery += country;
  }

  const std::string beerQuery = "beer in " + std::string(city);

  try {
    const std::string regionExtract = FetchExtract(regionQuery);
    const std::string beerExtract = FetchExtract(beerQuery);

    if (!regionExtract.empty()) {
      result += regionExtract;
    }
    if (!beerExtract.empty()) {
      if (!result.empty())
        result += "\n\n";
      result += beerExtract;
    }
  } catch (const std::runtime_error &e) {
    spdlog::debug("WikipediaService lookup failed for '{}': {}", regionQuery,
                  e.what());
  }

  cache_.emplace(key, result);
  return result;
}