#!/bin/sh
set -euf
NL='
'
BN="${0##*/}"

# note: use setsid when calling this with exec
# e.g. if you make this a void user-service, do
# exec setsid twitch-notify <channel list>

errecho() { echo "$*" >&2 ; }
fail() { errecho "error: $BN: $*"; exit 1; }

innerclean() {
	[ -f "${1:-}" ] && rm -f "$1"
	[ -f "${IMG:-}" ] && rm -f "$IMG"
}
clean() {
	trap 'exit' INT HUP TERM EXIT
	[ -f "${HTML:-}" ] && rm -f "$HTML"
	[ -f "${IMG:-}" ] && rm -f "$IMG"
	[ -d "${DIR:-}" ] && rm -rf "$DIR"
	kill 0
}

# with the sleep 0.5, 2 tries gives like 99.9% accuracy
check() {
	tmphtml="$2"
	max_tries=2
	trap 'innerclean "$tmphtml"' INT HUP TERM EXIT
	curl --connect-timeout 10 -s -o "$2" -L "https://twitch.tv/$1"
	if [ -n "$(pup 'script[type="application/ld+json"]' < "$2")" ]; then
		if [ ! -f "$DIR/$1" ]; then
			touch "$DIR/$1"
			IMG="$(mktemp -t "twitch-notify-img.XXXX")"
			curl --connect-timeout 10 -s -o "$IMG" -L "$(pup 'meta[property="og:image"]' 'attr{content}' < "$2")"
			TITLE="$(pup 'script[type="application/ld+json"] text{}' < "$2" | jq -r '.[0].description')"
			CODE="$(notify-send -A "watch" -A "copy" -t 10000 -u normal -i "$IMG" "$1 is online!$NL$NL\"$TITLE\"")"
			case "${CODE:-999}" in
				0) xdg-open "https://twitch.tv/$1" ;;
				1) printf '%s' "https://twitch.tv/$1" | xclip -sel clipboard ;;
				*) : ;;
			esac
			rm -f "$IMG"
		fi
	elif [ "$i" -lt "$max_tries" ]; then
		i=$((i + 1))
		sleep 0.5
		check "$1" "$2"
	else
		[ -f "$DIR/$1" ] && rm "$DIR/$1"
		echo "$1 is most likely offline or doesn't exist."
	fi
	[ -f "$2" ] && rm -f "$2"
}

# janky way to do this but fuck it. easiest one that doesn't get race conditioned
# if a file with their name exists in DIR, they're online
DIR="${XDG_RUNTIME_DIR:-"${TMPDIR:-/tmp}"}/twitch-notify-dir-$USER"

while getopts :t:l OPT; do
	case "$OPT" in
		t) SLEEP_INTERVAL="$OPTARG" ;; # in seconds, default 180
		l) [ -d "$DIR" ] && printf 'ONLINE CHANNELS:\n' && ls -w 1 "$DIR"; exit 0 ;;
		*) fail "unknown option: -$OPTARG" ;;
	esac
done
shift "$((OPTIND - 1))"
# this mkdir should prevent any "someone's trying to override this" type beats
mkdir -m 700 -- "$DIR" || fail "$DIR already exists! remove it if no daemon is running"
trap 'clean' INT HUP TERM EXIT

while
	for name; do
		i=0
		HTML="$(mktemp -t "twitch-notify-html.XXXX")"
		check "$name" "$HTML" &
	done
do
	sleep "${SLEEP_INTERVAL:-60}"
done &
wait