{ pkgs, lib, config, ... }:
let inherit (lib) types;
    inherit (config.networking) hostName domain;
in
{
imports = [
  ./modules.nix
  defaults/predictable-interface-names.nix
];
nix = {
  #binaryCaches = lib.mkForce [];
  extraOptions = ''
  '';
  # Use gc.automatic to keep disk space under control.
  gc = {
    automatic = lib.mkDefault true;
    dates = lib.mkDefault "weekly";
    options = lib.mkDefault "--delete-older-than 30d";
  };
  nixPath = [
    # WARNING: this is a hack to avoid copying Nixpkgs
    # a second time into the Nix store.
    # It makes only sense when Nixpkgs is already in the Nix store,
    # and is registered.
    "nixpkgs=${toString pkgs.path}:nixpkgs-overlays=${../nixpkgs}/overlays.nix"
  ];
};

nixpkgs = {
  config = {
    allowUnfree = false;
    /*
    packageOverrides = pkgs: {
      postfix = pkgs.postfix.override {
        withLDAP = true;
      };
    };
    */
  };
  overlays = import ../nixpkgs/overlays.nix;
};

documentation.nixos = {
  enable = false; # NOTE: useless on a server, and CPU intensive.
};

time = {
  timeZone = "Europe/Paris";
};

i18n = {
  defaultLocale = "fr_FR.UTF-8";
};

console = {
  font   = "Lat2-Terminus16";
  keyMap = "fr";
};

# Always try to start all the units (default.target)
# because systemd's emergency shell does not try to start sshd.
# https://wiki.archlinux.org/index.php/systemd#Disable_emergency_mode_on_remote_machine
systemd.enableEmergencyMode = false;

# This is a remote headless server: always reboot on a kernel panic,
# to not have to physically go power cycle the apu2e4.
# Which happens if the wrong ZFS password is used
# but the boot is manually forced to continue.
# Using kernelParams instead of kernel.sysctl
# sets this up as soon as the initrd.
boot.kernelParams = [ "panic=10" ];

boot.cleanTmpDir = true;
boot.tmpOnTmpfs = true;

networking = {
  # Fix hostname --fqdn
  # See: https://github.com/NixOS/nixpkgs/issues/10183#issuecomment-537629621
  hosts = {
    "127.0.1.1" = lib.mkForce [ "${hostName}.${domain}" hostName ];
    "::1"       = lib.mkForce [ "${hostName}.${domain}" hostName "localhost" ];
  };
  search = [ domain ];
};

services = {
  openssh = {
    enable = true;
    passwordAuthentication = false;
    extraConfig = ''
    '';
  };
  journald = {
    extraConfig = ''
      Compress=true
      MaxRetentionSec=3month
      Storage=persistent
      SystemMaxUse=500M
    '';
  };
};

environment = {
  #checkConfigurationOptions = false;
  #etc.nixpkgs.source = (pkgs.runCommandLocal "pkgs.path" {propagatedBuildInputs=[pkgs.path]; buildInputs=[pkgs.path];} "mkdir $out");
  systemPackages = with pkgs; [
    pkgs.path # WARNING: this is a hack to register the path to Nixpkgs. See nix.nixPath.
    binutils
    conntrack-tools
    #dnsutils
    dstat
    gnupg
    htop
    inetutils
    iotop
    linuxPackages.cpupower
    lsof
    mailutils
    multitail
    ncdu
    nmon
    pv
    swaplist
    tcpdump
    tmux
    tree
    vim
    which
  ];

  etc."inputrc".text = lib.readFile defaults/readline/inputrc;

  variables.SYSTEMD_LESS = "FKMRX";
};

programs = {
  bash = {
    interactiveShellInit = ''
      bind '"\e[A":history-search-backward'
      bind '"\e[B":history-search-forward'

      # Ignore duplicate commands, ignore commands starting with a space
      export HISTCONTROL=erasedups:ignorespace
      export HISTSIZE=42000

      # Append to the history instead of overwriting (good for multiple connections)
      shopt -s histappend

      # Enable ** file pattern
      shopt -s globstar

      # Convenient mkdir wrapper
      mkcd() { mkdir -p "$1" && cd "$1"; }
    '';
    shellAliases = {
      cl = "clear";
      l  = "ls -alh";
      ll = "ls -al";
      ls = "ls --color=tty";
      mem = "ps -e -orss=,user=,args= | sort -b -k1,1n";

      s="sudo systemctl";
      st="sudo systemctl status";
      s-u="systemctl --user";
      j="sudo journalctl -u";

      nixos-clean="sudo nix-collect-garbage -d";
      nixos-history="sudo nix-env --list-generations --profile /nix/var/nix/profiles/system";
      nixos-rollback="sudo nixos-rebuild switch --rollback";
      nixos-update="sudo nix-channel --update";
      nixos-upgrade="sudo nixos-rebuild switch";
      nixos-upstream="sudo nix-channel --list";
    };
  };
  gnupg = {
    agent = {
      pinentryFlavor = "curses";
    };
  };
  mosh.enable = true;
  mtr.enable = true;
};
}