#!/usr/bin/env bash
delay=0.2
fixed=0
l=0 l2=0 w2=0
while getopts 'fw:d:h' o; do

	case $o in
	d) delay="$OPTARG" ;;
	f) fixed=1 ;;
	w) w="$((OPTARG))" ;;
	h) nr=1 ;&
	*)
		cat >&2 <<EOF
Usage: $0 [ -h | [ [opts] [text ...] ]

Prints [text ...] as a scrolling marquee

Options:
	-f     fix width: do not change on SIGWINCH
	-w n   set width: do not detect (implies -f)
	-d n   set delay: see documentation on Bash's \`sleep\`
	-h     see this help
EOF
		exit $((1 - nr))
		;;
	esac

done
shift "$((OPTIND - 1))"
pre="$*"

if ((w == 0)); then
	winch_handler() {
		w="$(tput cols)"
		s="$(printf "%${w}s" "$pre")"
	}
	winch_handler
	((fixed != 1)) && trap "winch_handler" SIGWINCH
else
	s="$(printf "%${w}s" "$pre")"
fi

while sleep "$delay"; do
	printf '%s\r' "${s:$l:$w}${s:$l2:$w2}"
	((l = (l + 1) % ${#s}))
	((l2 = (l - ${#s}) > 0 ? (l - ${#s}) : 0))
	((w2 = (l + w - ${#s}) > 0 ? (l + w - ${#s}) : 0))
done