{
  config,
  inputs,
  lib,
  pkgs,
  ...
}:
with lib; let
  cfg = config.custom.services.flatpak;
in {
  options.custom.services.flatpak.enable = mkOption {default = false;};

  config = mkIf cfg.enable {
    # https://wiki.nixos.org/wiki/Flatpak
    # https://github.com/gmodena/nix-flatpak
    services.flatpak = {
      enable = true;
      uninstallUnmanaged = true; # Immutable flatpaks
      update.auto.enable = true; # Auto update flatpaks weekly

      #!! Installation occurs in background as a oneshot service
      #?? flatpak search NAME
      packages =
        optionals config.custom.default [
          "com.github.tchx84.Flatseal"
        ]
        ++ optionals config.custom.minimal [
          "net.retrodeck.retrodeck"
        ]
        ++ optionals config.custom.full [
          "app.drey.Biblioteca"
        ];
    };

    # Theme packages must be installed system-wide for flatpaks
    environment.systemPackages = with pkgs; [
      adw-gtk3
      google-cursor
      papirus-icon-theme
    ];
  };
}