let
  common = import ./common.nix;
in
rec {
  getQbittorrent = serviceData:
    let
      qbt =
        if serviceData ? qbittorrent then
          common.ensureAttrset "config/services.nix qbittorrent" serviceData.qbittorrent
        else
          throw "config/services.nix must define qbittorrent attrset.";

      webPort =
        if qbt ? port then
          common.ensureInt "config/services.nix qbittorrent.port" qbt.port
        else
          throw "config/services.nix qbittorrent.port must exist.";

      rootDir =
        if qbt ? root_dir then
          common.ensureNonEmptyString "config/services.nix qbittorrent.root_dir" qbt.root_dir
        else
          throw "config/services.nix qbittorrent.root_dir must exist.";

      vpn =
        if qbt ? vpn then
          common.ensureAttrset "config/services.nix qbittorrent.vpn" qbt.vpn
        else
          throw "config/services.nix qbittorrent.vpn must exist.";

      usernameFile =
        if vpn ? username_file then
          common.ensureNonEmptyString "config/services.nix qbittorrent.vpn.username_file" vpn.username_file
        else
          throw "config/services.nix qbittorrent.vpn.username_file must exist.";

      passwordFile =
        if vpn ? password_file then
          common.ensureNonEmptyString "config/services.nix qbittorrent.vpn.password_file" vpn.password_file
        else
          throw "config/services.nix qbittorrent.vpn.password_file must exist.";
    in
      {
        port = webPort;
        root_dir = rootDir;
        vpn = {
          username_file = usernameFile;
          password_file = passwordFile;
        };
      };
}