{ config, pkgs, ... }:

{
  # Bootloader.
  boot.loader.systemd-boot.enable = true;
  boot.loader.efi.canTouchEfiVariables = true;

  # Setup keyfile.
  boot.initrd.secrets = {
    "/crypto_keyfile.bin" = null;
  };

  # Enables wireless support via wpa_supplicant.
  # networking.wireless.enable = true;

  # Enable networking.
  networking.networkmanager.enable = true;

  networking.nameservers = [
    # https://www.kuketz-blog.de/empfehlungsecke/#dns
    # dot.ffmuc.net (supports DNSSEC)
   "5.1.66.255" "185.150.99.255"
    # https://www.kuketz-blog.de/empfehlungsecke/#dns
    # unfiltered.adguard-dns.com (supports DNSSEC)
   "94.140.14.140" "94.140.14.141"
  ];

  # Set your time zone.
  time.timeZone = "Europe/Berlin";

  # Select internationalisation properties.
  i18n.defaultLocale = "en_US.UTF-8";

  i18n.extraLocaleSettings = {
    LC_ADDRESS = "de_DE.UTF-8";
    LC_IDENTIFICATION = "de_DE.UTF-8";
    LC_MEASUREMENT = "de_DE.UTF-8";
    LC_MONETARY = "de_DE.UTF-8";
    LC_NAME = "de_DE.UTF-8";
    LC_NUMERIC = "de_DE.UTF-8";
    LC_PAPER = "de_DE.UTF-8";
    LC_TELEPHONE = "de_DE.UTF-8";
    LC_TIME = "de_DE.UTF-8";
  };

  # Configure console keymap.
  console.keyMap = "de-latin1-nodeadkeys";

  # Allow unfree packages.
  nixpkgs.config.allowUnfree = true;

  # Define a user account. Don't forget to set a password with `passwd`.
  users.users.yoda = {
    isNormalUser = true;
    description = "Yoda";
    extraGroups = [ "networkmanager" "wheel" ];
    packages = with pkgs; [
      # Nix dependency management.
      niv
    ];
  };

  # List packages installed in system profile. To search, run:
  # $ nix search wget
  environment.systemPackages = with pkgs; [
  ];

  # SystemMaxFileSize: Defaults to one eighth of the values configured with SystemMaxUse= and RuntimeMaxUse=, so that usually seven rotated journal files are kept as history.
  # MaxFileSec: To ensure that not too much data is lost at once when old journal files are deleted, it might make sense to change this value from the default of one month.
  # https://www.freedesktop.org/software/systemd/man/journald.conf.html
  services.journald.extraConfig = ''
    SystemMaxUse=800M
    MaxFileSec=7day
  '';

  # BTRFS compression.
  #
  # `nixos-generate-config` does not detect mount options, so we add them here.
  # https://nixos.wiki/wiki/Btrfs#Compression
  fileSystems = {
    "/".options = [ "compress=zstd" ];
  };

  # BTRFS scrub.
  #
  # Scrubbing is the process of checking file consistency.
  # Scrubbing may be done "online", meaning you don't need to unmount a subvolume to scrub it.
  # https://nixos.wiki/wiki/Btrfs#Scrubbing
  # Btrfs scrub is "[a]n online filesystem checking tool. Reads all the data and metadata on the filesystem and uses checksums and the duplicate copies from RAID storage to identify and repair any corrupt data."
  # https://wiki.archlinux.org/title/btrfs#Scrub
  # The scrub command operates on a whole filesystem, not just individual subvolumes.
  # https://unix.stackexchange.com/a/724412
  #
  # Manually:
  #   sudo btrfs scrub start /
  #   sudo btrfs scrub status /
  #   #=> UUID:             01f67928-9b35-48b2-aaa6-c58ff6c440a8
  #   #=> Scrub started:    Sat Sep 16 12:54:47 2023
  #   #=> Status:           finished
  #   #=> Duration:         0:00:42
  #   #=> Total to scrub:   64.43GiB
  #   #=> Rate:             1.53GiB/s
  #   #=> Error summary:    no errors found
  services.btrfs.autoScrub = {
    enable = true;
    interval = "monthly";
    fileSystems = [ "/" ];
  };

  nix.settings.auto-optimise-store = true;

  # Firewall
  #
  # Open ports in the firewall.
  #networking.firewall.allowedTCPPorts = [ ... ];
  #networking.firewall.allowedUDPPorts = [ ... ];
  # Or disable the firewall altogether.
  #networking.firewall.enable = false;

  # This value determines the NixOS release from which the default
  # settings for stateful data, like file locations and database versions
  # on your system were taken. It's perfectly fine and recommended to leave
  # this value at the release version of the first install of this system.
  # Before changing this value read the documentation for this option
  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
  system.stateVersion = "23.05"; # Did you read the comment?
}