Bash - hack for `getopts` to handle a single short or long option with no args

getopts_single_short_long.sh

#!/usr/bin/env bash

# this is a total hack for `getopts` so it handles a single short or long option
#  - valid options are: -a, -h, --all, --help
#  - no args for options are allowed


die () {
    tput setaf 1; echo -en "\u2717 "; tput sgr0
    tput bold; echo "$*" 1>&2; tput sgr0
    exit 1
}

err_msg="fatal: only valid options are: -a, -h, --all, --help (with no args)"
while getopts ":ah-:" opt; do
    if [[ -n "${!OPTIND+a}" ]]; then die "${err_msg}"; fi
    if [ "${opt}" == "-" ]; then # long option: reformulate opt and OPTARG
        opt="${OPTARG%%=*}" # extract long option name
        OPTARG="${OPTARG#"${opt}"}" # extract long option arg
    fi
    case "${opt}" in
        a | all )
            OPT_ALL="true"
            if [ -n "${OPTARG}" ]; then die "${err_msg}"; fi
            ;;
        h | help )
            OPT_HELP=true
            if [ -n "${OPTARG}" ]; then die "${err_msg}"; fi
            ;;
        \? | * )
            die "${err_msg}"
            ;;
    esac
done

if [ -n "${OPT_ALL}" ]; then
    echo "-a or --all option was provided"
elif [ -n "${OPT_HELP}" ]; then
    echo "-h or --help option was provided"
else
    echo "no option provided"
fi