#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  muffle [--] COMMAND...
		  muffle -h
	EOF
}

help() {
	cat <<-'EOF'


		Options:
		  -h, --help    show this message

		  COMMAND       the COMMAND to be muffled


		Conditionally omit STDOUT and STDERR of COMMAND:
		if command exits with an error, print its original output to the
		corresponding streams, but when there is no error, throw the
		output away, "muffling" the COMMAND.


		Examples:

		  Only print anything if the test fails:

		    $ muffle sh tests/assert-makefile.sh
	EOF
}


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))


OUT="$(mkstemp)"
ERR="$(mkstemp)"
trap 'rm -f "$OUT" "$ERR"' EXIT

STATUS=0
"$@" 1>"$OUT" 2>"$ERR" || STATUS=$?

if [ "$STATUS" != 0 ]; then
	cat "$OUT"
	cat "$ERR" >&2
	exit "$STATUS"
fi