qr

#!/bin/bash

set -e

usage() {
	echo >&2 "Usage: ${0##*/} $(gawk -v line_n=100 \
		'/^\s+case\>/ {parse=1; next}
		/^\s+esac\>/ {exit}
		!parse {next}
		match($0, /^\s*([\-|a-z0-9]+)\)/, a) {
			if (ac==0 || ac<2) ac=""; else ac=sprintf(ac==2?" ..":" <%s>", ac-1)
			if (ap) {
				ac=sprintf("[%s%s] ", ap, ac); acn=length(ac)
				if (an && an+acn>line_n) { printf("\n  "); an=acn; } else an+=acn
				printf("%s", ac); }
			ap=a[1]; ac=0 }
		{for (i=1;i<NF;i++) if (match($i, /\<shift\>/)) ac++}' $0)"
	echo >&2
	echo >&2 "Create/decode QR code image."
	echo >&2 " Create: displays it (using feh, default if DISPLAY= is set) or prints path to stdout."
	echo >&2 " Decode: requires image(s), prints decoded contents to stdout."
	echo >&2 "Different parameters determine type of data encoded there."
	echo >&2 "NOTE: anything running on the system can see all passed command-line options!!!"
	echo >&2
	echo >&2 "Examples:"
	echo >&2 "  Create QR from stdin to display: qr <somefile"
	echo >&2 "    From raw string (arg or stdin): qr -r line-of-text"
	echo >&2 "    WiFi AP: qr -v -s myssid -p some-long-passphrase"
	echo >&2 "  Decode QR from image to stdout: qr image.png"
	echo >&2
	exit ${1:-1}
}

display= out= opts= verbose= image=()
raw= wifi= wifi_ssid= wifi_pass=

while [[ -n "$1" ]]; do
	case "$1" in
		-h|--help) usage 0 ;;
		-v) shift; verbose=t ;;
		-x) shift; set -x ;;

		-d|--display) shift; display=t ;;
		-o|--out-file) shift; out=$1; shift ;;
		--opts) shift; opts=$1; shift ;;

		-r|--raw-text) shift; raw=$1; shift || raw=$(</dev/stdin) ;;
		-s|--ssid) shift; wifi=t; wifi_ssid=$1; shift ;;
		-p|--pass) shift; wifi=t; wifi_pass=$1; shift ;;
		-i|--image) shift; image+=( "$1" ); shift ;;

		welp) exit 1 ;;
		*) image+=( "$1" ); shift ;;
	esac
done

[[ "${#image[@]}" -eq 0 ]] || {
	err=0
	for img in "${image[@]}"; do zbarimg -q "$img" || err=1; done
	exit "$err"; }

[[ -n "$display" || -n "$out" || -z "$DISPLAY" ]] || display=t
dst=$out
[[ -n "$dst" ]] || {
	[[ -z "$display" ]] \
		&& { dst="$HOME"/Desktop; [[ -d "$dst" ]] || dst=$HOME; } \
		|| { [[ -n "$XDG_RUNTIME_DIR" ]] && dst=$XDG_RUNTIME_DIR || dst=/tmp; }
	dst="${dst}/qr-$(printf '%(%Y%m%d%H%M%S)T' -1).png"; }
opts=( $opts )

qr=()
[[ -z "$raw" ]] || qr+=( "$raw" )
[[ -z "$wifi" ]] || {
	[[ "${#qr[@]}" -eq 0 ]] || { echo >&2 "ERROR: conflicting output mode opts"; exit 1; }
	qr+=( "WIFI:T:WPA;S:${wifi_ssid};P:${wifi_pass};;" ); }
[[ "${#qr[@]}" -gt 0 ]] || qr+=( -r /dev/stdin )
[[ "${#qr[@]}" -gt 0 ]] || { echo >&2 "ERROR: no parameters to encode specified"; exit 1; }

[[ -z "$verbose" ]] || echo "${qr[@]}"
qrencode -o "$dst" "${opts[@]}" -- "${qr[@]}" \
	|| { err=$?; echo >&2 "ERROR: qrencode operation failed"; exit $err; }
if [[ -z "$display" ]]
then [[ -n "$out" ]] || echo "$dst"
else
	trap 'rm -f "$dst"' EXIT INT
	feh --force-aliasing -FZYxs --image-bg white "$dst" ||:
fi