nixcfg/packages/nixos-revision/default.nix

{
  pkgs,
  lib,
  gitHostCommitUrl ? "https://git.hoyer.xyz/harald/nixcfg/commit",
  ...
}:

let
  inherit (lib.metacfg) override-meta;

  new-meta = with lib; {
    description = "A helper show the current git revision of the system configuration.";
    license = licenses.asl20;
    maintainers = with maintainers; [ jakehamilton ];
  };

  package = pkgs.writeShellScriptBin "nixos-revision" ''
    HAS_HELP=false
    HAS_OPEN=false

    while [[ $# -gt 0 ]]; do
    	case $1 in
    		-h|--help)
    			HAS_HELP=true
    			shift
    			;;
    		-o|--open)
    			HAS_OPEN=true
    			shift
    			;;
    		*)
    			shift
    			;;
    	esac
    done

    if [ $HAS_HELP == true ]; then
    	HELP_MSG="
    nixos-revision

    USAGE

      nixos-revision [options]

    OPTIONS

      -h, --help              Show this help message
      -o, --open              Open the revision on GitHub

    EXAMPLES

      $ # Print the current revision
      $ nixos-revision

      $ # Open the current revision on GitHub
      $ nixos-revision --open
    "
    	echo "$HELP_MSG"
      exit 0
    fi

    REVISION=$(nixos-version --json | ${pkgs.jq}/bin/jq -r .configurationRevision)

    if [ $HAS_OPEN == true ]; then
      GITHUB_URL="${gitHostCommitUrl}/$REVISION"
      echo "Opening URL: $GITHUB_URL"
      ${pkgs.xdg-utils}/bin/xdg-open $GITHUB_URL
    else
      echo $REVISION
    fi
  '';
in
override-meta new-meta package