{ pkgs
, config
, ...
}:

let
in {
  home.file.".nix-channels".text = ''
    https://nixos.org/channels/nixos-18.09 nixos
    https://nixos.org/channels/nixos-unstable nixos-unstable
  '';

  home.activation.removeExistingNixChannels = config.lib.dag.entryBefore ["checkLinkTargets"] ''
    $DRY_RUN_CMD ${pkgs.writeScript "activation-script" ''
    set -ex
    if test -f $HOME/.nix-channels; then
      echo Moving existing file away...
      touch $HOME/.nix-channels.dummy
      mv --backup=numbered $HOME/.nix-channels.dummy $HOME/.nix-channels
      rm $HOME/.nix-channels
    fi
    ''};
  '';
}