# NixOps configuration for the hosts using Yubikeys

{ config, pkgs, lib, ... }:

{

  services = {
    udev = {
      packages = [
        pkgs.yubikey-personalization   # A library and command line tool to personalize YubiKeys
        pkgs.libu2f-host               # A C library and command-line tool that implements the host-side of the U2F protocol
      ];
      extraRules = let
        dependencies = with pkgs; [ coreutils gnupg gawk gnugrep ];
        clearYubikey = pkgs.writeScript "clear-yubikey" ''
          #!${pkgs.stdenv.shell}
          export PATH=${pkgs.lib.makeBinPath dependencies};
          keygrips=$(
            gpg-connect-agent 'keyinfo --list' /bye 2>/dev/null \
              | grep -v OK \
              | awk '{if ($4 == "T") { print $3 ".key" }}')
          for f in $keygrips; do
            rm -v ~/.gnupg/private-keys-v1.d/$f
          done
          gpg --card-status 2>/dev/null 1>/dev/null || true
        '';
        clearYubikeyUser = pkgs.writeScript "clear-yubikey-user" ''
          #!${pkgs.stdenv.shell}
          ${pkgs.sudo}/bin/sudo -u craige ${clearYubikey}
        '';
      in ''
        ACTION=="add|change", SUBSYSTEM=="usb", ATTRS{idVendor}=="1050", ATTRS{idProduct}=="0407", RUN+="${clearYubikeyUser}"
      '';
    };
    pcscd.enable = true;             # Enable PCSC-Lite daemon
  };

  # Additional packages used with the Yubikey
  environment = {
    systemPackages = with pkgs; [
      paperkey                      # Store OpenPGP or GnuPG on paper
      yubikey-manager               # CLI tool for configuring any YubiKey over USB
      yubikey-manager-qt            # Configure any YubiKey over USB interfaces
      yubikey-personalization       # Lib & CLI tool to personalize YubiKeys
      yubikey-personalization-gui   # QT based utility to facilitate Yubikey reconfiguration
      yubioath-desktop              # Yubikey Desktop Authenticator
    ];
    shellInit = ''
      export GPG_TTY="$(tty)"
      gpg-connect-agent /bye
      export SSH_AUTH_SOCK="/run/user/$UID/gnupg/S.gpg-agent.ssh"
    '';
  };

  programs = {
    ssh.startAgent = false;      # Disable the SSH Agent
    gnupg.agent = {
      enable = true;             # Enable GPG Agent
      enableSSHSupport = true;   # Enable SSH agent support in GnuPG agent
    };
  };

}