export module routemon:database;

import std;
import :sqlite3;

namespace routemon::database {

static constexpr std::int64_t expected_database_version = 1;

export class connection
{
  sqlite3::connection dbc_;

  explicit connection(sqlite3::connection dbc) : dbc_{std::move(dbc)} {}

  friend auto open(std::string const& filename) -> std::shared_ptr<connection>;

public:
  // Nothing here yet
};

export auto open(std::string const& filename) -> std::shared_ptr<connection>
{
  auto dbc = sqlite3::open(filename);
  try
  {
    auto version = std::optional<std::int64_t>{};
    dbc.query("SELECT version FROM migration;").scan_single(version);
    if (!version)
      throw std::runtime_error{"failed to fetch database migration version"};
    if (version != expected_database_version)
    {
      throw std::runtime_error{std::format(
          "database migration version ({}) does not match expected "
          "version ({}), consider running migrations",
          *version, expected_database_version)};
    }
  }
  catch (std::exception const& e)
  {
    throw std::runtime_error{std::format(
        "failed to query database version: {}", e.what())};
  }
  return std::shared_ptr<connection>{new connection{std::move(dbc)}};
}

} // namespace routemon::database