#!/usr/bin/env dash
# shellcheck disable=SC2086
# shellcheck source=/dev/null
. %SHELL_LIBRARY_PATH

help() {
    cat << EOF
    --branch | -b  [branchname]     select a branch to update from.
    --help   | -h                   output this help.
EOF
    exit "$1";
}

BRANCH="";

while [ "$#" -gt 0 ];do
    case "$1" in
        "--help" | "-h")
            help 0;
            ;;
        "--branch" | "-b")
            if [ -n "$2" ];then
                BRANCH="$2";
            else
                error "$1 requires an argument";
                help 1;
            fi
            shift 2;
            ;;
        *)
            error "the option $1 does not exist!";
            help 1;
            ;;
    esac
done


cd /etc/nixos || die "No /etc/nixos"
[ "$BRANCH" = "" ] || git switch "$BRANCH";
git pull --rebase
nixos-rebuild switch