#!/usr/bin/env sh

USAGE="usage: autonginx <URL> <IP> <PORT>

URL:  url à laquelle le service sera accessible (exemple.urlab.be)
IP:   adresse ip locale du service (127.0.0.1 si sur cette machine, 172.23.100.X sinon)
PORT: port utilisé par le service (entre 1 et 65535; certains ports sont déjà utilisés)"

error() {
	echo "$@" >&2
	exit 1
}

sanitize() {
	if ! [ "$PORT" -eq "$PORT" ] 2> /dev/null; then
        error "$USAGE"
	fi
	if [ "$PORT" -lt 1 ] || [ "$PORT" -gt 65535 ]; then
		error "$USAGE"
	fi
	case "$URL" in
		*.urlab.be) SUBDOMAIN=${URL%.urlab.be} ;;
		*) error "$USAGE";;
	esac
	if [ "$SUBDOMAIN" = "" ]; then
		error "$USAGE"
	fi
	if [ "$(expr "$SUBDOMAIN" : '[A-Za-z0-9][A-Za-z0-9\-]\{0,61\}[A-Za-z0-9]\{0,1\}')" != "${#SUBDOMAIN}" ]; then
		error "$USAGE"
	fi
	if [ "$IP" != "127.0.0.1" ]; then
		case "$IP" in
			127.0.0.1) ;;
			172.23.100.[0-9]*) 
				LAST=${IP#172.23.100.}
				if [ "$LAST" -lt 2 ] || [ "$LAST" -gt 254 ]; then
					error "$USAGE"
				fi ;;
			*) error "$USAGE";;
		esac
	fi
}

verify() {
	if ! ping -c 1 -W 1 "$IP" >/dev/null 2>/dev/null ; then
		error "Error : Cannot reach host $IP"
	fi
	if ! timeout 1 sh -c "(echo > /dev/tcp/$IP/$PORT) >/dev/null 2>&1"; then
		error "Error : Port $PORT isn't open"
	fi
}

main() {
	if [ "$(id -u)" -ne 0 ]; then
		error "Please run as root." >&2
	fi
	if [ $# != 3 ]; then
		error "$USAGE"
	fi

	URL="$1"
	IP="$2"
	PORT="$3"
	NGINX="server {
       listen 80;
       listen [::]:80;

       server_name $URL;

       location / {
		   proxy_pass http://$IP:$PORT/;
		   include proxy_params;
       }
}"

	sanitize
	verify
	mkdir -p /etc/nginx/sites-available
	mkdir -p /etc/nginx/sites-enabled
	sh -c 'echo "${0}" > /etc/nginx/sites-available/${1}' "$NGINX" "$URL"
	ln -s "/etc/nginx/sites-available/$URL" "/etc/nginx/sites-enabled/$URL"
	if nginx -t >/dev/null 2>/dev/null; then
		rm -f "/etc/nginx/sites-available/$URL" "/etc/nginx/sites-enabled/$URL"
		error "Error : Nginx config failed"
	fi
	if certbot run --nginx -d "$URL"; then
		rm -f "/etc/letsencrypt/live/$URL" "/etc/letsencrypt/archive/$URL"
		error "Error : certbot failure"
	fi
}

main "$@"