{ config, lib, pkgs, ... }:
with lib;
let cfg = config.kyouma.update-nixfiles;
in {
  options.kyouma.update-nixfiles = {
    enable = mkEnableOption "automatically update nixfiles inputs";
    privateKey = mkOption {
      type = types.str;
      default = "";
      description = "Private key path";
    };
    signingKey = mkOption {
      type = types.str;
      default = "";
      description = "Public Key";
    };
    runFreq = mkOption {
      type = types.str;
      default = "*-*-* 04:20:00";
      description = "How often nixfiles should be updated. See {manpage}`systemd.timer(5)`";
    };
  };
  config = mkIf cfg.enable {
    users.groups.update-nixfiles = {};
    users.users.update-nixfiles = {
      createHome = true;
      group = "update-nixfiles";
      home = "/var/lib/update-nixfiles";
      isSystemUser = true;
      useDefaultShell = true;
    };
    home-manager.users.update-nixfiles = {
      home.stateVersion = "23.11";
      programs.git = {
        enable = true;
        signing.key = builtins.toFile "signingKey" cfg.signingKey;
        signing.signByDefault = true;
        userName = "Update Bot";
        userEmail = "update-nixfiles-bot@kyouma.net";
        extraConfig = {
          gpg.format = "ssh";
        };
      };
      programs.ssh = {
        addKeysToAgent = "yes";
        matchBlocks."git.bsd.gay".indentityFile = cfg.privateKey;
      };
      services.ssh-agent.enable = true;
    };
    programs.ssh = {
      knownHosts."git.bsd.gay".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHd48YPVXBWVdQwVAF16Ihs7FNTPmD1kMUnOfQttc1bA";
    };
    systemd.services.update-nixfiles = {
      requires = [ "network-online.target" ];
      after = [ "network-online.target" ];
      restartIfChanged = false;
      unitConfig.X-StopOnRemoval = false;

      serviceConfig = {
        ExecStart = "${pkgs.update-nixfiles}/bin/update-nixfiles";
        User = "update-nixfiles";
      };
    };
    systemd.timers.update-nixfiles = {
      wantedBy = [ "timers.target" ];
      timerConfig = {
        OnCalendar = cfg.runFreq;
      };
      requires = [ "network-online.target" ];
      after = [ "network-online.target" ];
    };
    environment.systemPackages = [ pkgs.update-nixfiles ];
  };
}