{
  config,
  lib,
  ...
}:
with lib; {
  options.constants = {
    domain = mkOption {
      type = types.str;
      default = "invariantspace.com";
      description = ''
        The domain for all devices.
      '';
    };
    homeDir = mkOption {
      type = types.str;
      default = "/home/${config.constants.userName}";
      description = ''
        The home directory for the default user.
      '';
    };
    localhost = mkOption {
      type = types.str;
      default = "127.0.0.1";
      description = ''
        The localhost address.
      '';
    };
    port = mkOption {
      type = types.attrsOf types.port;
      default = {
        aria2 = 30206;
        conduit = 29800;
        forgejo = 47674;
        headscale = 27327;
        http = 80;
        https = 443;
        jellyfin = 8096;
        jellyseerr = 52660;
        prowlarr = 30784;
        radarr = 37196;
        sonarr = 32438;
        vault = 25487;
      };
      description = ''
        The mapping from service to ports.
      '';
    };
    postMaster = mkOption {
      type = types.str;
      default = "${config.constants.userName}@${config.constants.domain}";
      description = ''
        The post master email address.
      '';
    };
    privateKeyFiles = mkOption {
      type = types.listOf types.str;
      default =
        if config.services.openssh.enable
        then map (key: key.path) config.services.openssh.hostKeys
        else ["/root/.ssh/${config.networking.hostName}"];
      description = ''
        The private key files for sops.
      '';
    };
    publicKeys = mkOption {
      type = types.listOf types.str;
      default = [
        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHPT/zRq5fffcUmjxcwG2cTr09fOa9O4rBUb6ob2CyNy macronova"
      ];
      description = ''
        The public keys for SSH authentication.
      '';
    };
    sopsFile = mkOption {
      type = types.path;
      default = ./secrets.yaml;
      description = ''
        The secrets file for device.
      '';
    };
    syncthingDevices = mkOption {
      type = types.attrsOf (types.attrsOf types.str);
      default = {
        nebula.id = "NJXA5XS-2PSWECD-UHBV7JH-IR2RSWY-PRUPFTZ-AHL7IN6-RXSLZKB-2FUNRQH";
        protostar.id = "TD6OQ6N-5UT7CQK-BSRRDEL-WEZI6QX-SFN7EQN-GWJH3TB-YLPKCM7-66FGOAP";
        quasar.id = "4IZ2RNQ-YTRM4C5-54X2MBV-ZL6Q6FO-TDETMJD-LBV3GV5-CO25QQU-2MG4PQR";
      };
      description = ''
        The device information for syncthing
      '';
    };
    userName = mkOption {
      type = types.str;
      default = "macronova";
      description = ''
        The username across all devices.
      '';
    };
    wildcard = mkOption {
      type = types.str;
      default = "0.0.0.0";
      description = ''
        The localhost address.
      '';
    };
  };
}