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

with lib;

let

  cfg = config.programs.gnupg;

in

{
  options.programs.gnupg = {
    agent.enable = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Enables GnuPG agent for every user session.
      '';
    };

    agent.enableSSHSupport = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Enable SSH agent support in GnuPG agent. Also sets SSH_AUTH_SOCK
        environment variable correctly.
      '';
    };
  };

  config = mkIf cfg.agent.enable {
    launchd.user.agents.gnupg-agent.serviceConfig = {
      ProgramArguments = [
        "${pkgs.gnupg}/bin/gpg-connect-agent" "/bye"
      ];
      RunAtLoad = cfg.agent.enableSSHSupport;
      KeepAlive = true;
    };

    environment.extraInit = ''
      # Bind gpg-agent to this TTY if gpg commands are used.
      export GPG_TTY=$(tty)
    '' + (optionalString cfg.agent.enableSSHSupport ''
      # SSH agent protocol doesn't support changing TTYs, so bind the agent
      # to every new TTY.
      ${pkgs.gnupg}/bin/gpg-connect-agent --quiet updatestartuptty /bye > /dev/null

      export SSH_AUTH_SOCK=$(${pkgs.gnupg}/bin/gpgconf --list-dirs agent-ssh-socket)
    '');
  };
}