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

help() {
    cat << EOF
    This is an Nixos flake update manager.

    Usage:
        "$name" [--branch <branchname>] [--help]

    Options:
        --branch | -b  [branchname]     select a branch to update from.
        --help   | -h                   output this help.
EOF
    exit "$1";
}
name="$0";
[ "$name" = "" ] && name=update;
tmp=$(mktmp);
git remote show origin | grep 'HEAD' | cut -d':' -f2 | sed -e 's/^ *//g' -e 's/ *$//g' > $tmp &
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"
git pull --rebase
[ "$BRANCH" = "" ] || git switch "$BRANCH";
nixos-rebuild switch
git switch "$(cat $tmp)";

# vim: ft=sh