#!/bin/sh
set -eu

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

help() {
	cat <<-'EOF'


		Options:
		  -n            invert when to do the muffling
		  -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

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


export TMPDIR="$XDG_RUNTIME_DIR"
OUT="$(mkstemp)"
ERR="$(mkstemp)"
F="$(mkstemp)"
trap 'rm -f "$OUT" "$ERR" "$F"' EXIT

timed() {
	ts -s -m '%.s'
}

{
	statusf "$F" "$@" | pre -n out | timed > "$OUT"
} 2>&1 | pre -n err | timed > "$ERR"

STATUS="$(cat "$F")"
if [ "$INVERT" = false -a "$STATUS" != 0 ] || [ "$INVERT" = true -a "$STATUS" = 0 ]; then
	sort -m "$OUT" "$ERR" | cut -d' ' -f2- | awk '{
		print substr($0, length($1) + 2) > "/dev/std" $1
	}'
	exit "$STATUS"
fi
