#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  prompt STRING|-
		  prompt -h
	EOF
}

help() {
	cat <<-'EOF'

		Options:
		  -h, --help    show this message

		  STRING        the text to be displayed in the prompt


		Display a prompt and return a value corresponding to the
		response.
	EOF
}

assert_arg() {
	if [ -z "$1" ]; then
		printf 'Missing %s.\n\n' "$2" >&2
		usage >&2
		exit 2
	fi
}


for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		*)
			;;
	esac
done

while getopts 'h' flag; do
	case "$flag" in
		h)
			usage
			help
			exit
			;;
		*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))

STRING="${1:-}"
assert_arg "$STRING" 'STRING'

printf '%s' "$STRING"
printf ' [Y/n]: '
read -r yesno
if [ "$yesno" != 'n' ] && [ "$yesno" != 'N' ]; then
	exit 0
else
	exit 1
fi