#!/usr/bin/env bash

timestamp() {
	date '+%Y-%m-%d %H:%M:%S'
}

getpublicip() {
	# shellcheck disable=SC2086
	natpmpc -g ${VPN_GATEWAY} | grep -oP '(?<=Public.IP.address.:.).*'
}

findconfiguredport() {
	curl -s -i --header "Referer: http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}" --cookie "$1" "http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}/api/v2/app/preferences" | grep -oP '(?<=\"listen_port\"\:)(\d{1,5})'
}

findactiveport() {
	# shellcheck disable=SC2086
	natpmpc -g ${VPN_GATEWAY} -a 0 0 udp ${NAT_LEASE_LIFETIME} >/dev/null 2>&1
	# shellcheck disable=SC2086
	natpmpc -g ${VPN_GATEWAY} -a 0 0 tcp ${NAT_LEASE_LIFETIME} | grep -oP '(?<=Mapped public port.).*(?=.protocol.*)'
}

qbt_login() {
	qbt_sid=$(curl -s -i --header "Referer: http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}" --data "username=${QBITTORRENT_USER}" --data-urlencode "password=${QBITTORRENT_PASS}" "http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}/api/v2/auth/login" | grep -oP '(?!set-cookie:.)SID=.*(?=\;.HttpOnly\;)')
	return $?
}

qbt_changeport() {
	curl -s -i --header "Referer: http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}" --cookie "$1" --data-urlencode "json={\"listen_port\":$2,\"random_port\":false,\"upnp\":false}" "http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}/api/v2/app/setPreferences" >/dev/null 2>&1
	return $?
}

qbt_checksid() {
	if curl -s --header "Referer: http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}" --cookie "${qbt_sid}" "http://${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}/api/v2/app/version" | grep -qi forbidden; then
		return 1
	else
		return 0
	fi
}

qbt_isreachable() {
	# shellcheck disable=SC2086
	nc -4 -vw 5 ${QBITTORRENT_SERVER} ${QBITTORRENT_PORT} &>/dev/null 2>&1
}

fw_delrule() {
	if (docker exec "${VPN_CT_NAME}" /sbin/iptables -L INPUT -n | grep -qP "^ACCEPT.*${configured_port}.*"); then
		# shellcheck disable=SC2086
		docker exec "${VPN_CT_NAME}" /sbin/iptables -D INPUT -i "${VPN_IF_NAME}" -p tcp --dport ${configured_port} -j ACCEPT
		# shellcheck disable=SC2086
		docker exec "${VPN_CT_NAME}" /sbin/iptables -D INPUT -i "${VPN_IF_NAME}" -p udp --dport ${configured_port} -j ACCEPT
	fi
}

fw_addrule() {
	if ! (docker exec "${VPN_CT_NAME}" /sbin/iptables -L INPUT -n | grep -qP "^ACCEPT.*${active_port}.*"); then
		# shellcheck disable=SC2086
		docker exec "${VPN_CT_NAME}" /sbin/iptables -A INPUT -i "${VPN_IF_NAME}" -p tcp --dport ${active_port} -j ACCEPT
		# shellcheck disable=SC2086
		docker exec "${VPN_CT_NAME}" /sbin/iptables -A INPUT -i "${VPN_IF_NAME}" -p udp --dport ${active_port} -j ACCEPT
		return 0
	else
		return 1
	fi
}

get_portmap() {
	res=0
	public_ip=$(getpublicip)

	if ! qbt_checksid; then
		echo "$(timestamp) | qBittorrent Cookie invalid, getting new SessionID"
		if ! qbt_login; then
			echo "$(timestamp) | Failed getting new SessionID from qBittorrent"
			return 1
		fi
	else
		echo "$(timestamp) | qBittorrent SessionID Ok!"
	fi

	configured_port=$(findconfiguredport "${qbt_sid}")
	active_port=$(findactiveport)

	echo "$(timestamp) | Public IP: ${public_ip}"
	echo "$(timestamp) | Configured Port: ${configured_port}"
	echo "$(timestamp) | Active Port: ${active_port}"

	# shellcheck disable=SC2086
	if [ ${configured_port} != ${active_port} ]; then
		if qbt_changeport "${qbt_sid}" ${active_port}; then
			if fw_delrule; then
				echo "$(timestamp) | IPTables rule deleted for port ${configured_port} on ${VPN_CT_NAME} container"
			fi
			echo "$(timestamp) | Port Changed to: $(findconfiguredport ${qbt_sid})"
		else
			echo "$(timestamp) | Port Change failed."
			res=1
		fi
	else
		echo "$(timestamp) | Port OK (Act: ${active_port} Cfg: ${configured_port})"
	fi

	if fw_addrule; then
		echo "$(timestamp) | IPTables rule added for port ${active_port} on ${VPN_CT_NAME} container"
	fi

	return $res
}

pre_reqs() {
	while read -r var; do
		if [ -z "${!var}" ]; then
			echo "$(timestamp) | ${var} is empty or not set."
			[ "$var" != "QBITTORRENT_USER" ] && [ "$var" != "QBITTORRENT_PASS" ] && exit 1
		fi
	done <<EOF
QBITTORRENT_SERVER
QBITTORRENT_PORT
QBITTORRENT_USER
QBITTORRENT_PASS
VPN_GATEWAY
CHECK_INTERVAL
NAT_LEASE_LIFETIME
EOF

	[ ! -S /var/run/docker.sock ] && {
		echo "$(timestamp) | Docker socket doesn't exist or is inaccessible"
		exit 2
	}

	return 0
}

load_vals() {
	public_ip=$(getpublicip)
	if qbt_isreachable; then
		if qbt_login; then
			configured_port=$(findconfiguredport "${qbt_sid}")
		else
			echo "$(timestamp) | Unable to login to qBittorrent at ${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}"
			exit 7
		fi
	else
		echo "$(timestamp) | Unable to reach qBittorrent at ${QBITTORRENT_SERVER}:${QBITTORRENT_PORT}"
		exit 6
	fi
	active_port=''
}

public_ip=
configured_port=
active_port=
qbt_sid=

pre_reqs && load_vals

# shellcheck disable=SC2086
[ -z ${public_ip} ] && {
	echo "$(timestamp) | Unable to grab VPN Public IP. Please check configuration"
	exit 3
}
# shellcheck disable=SC2086
[ -z ${configured_port} ] && {
	echo "$(timestamp) | qBittorrent configured port value is empty(?). Please check configuration"
	exit 4
}
[ -z "${qbt_sid}" ] && {
	echo "$(timestamp) | Unable to grab qBittorrent SessionID. Please check configuration"
	exit 5
}

while true; do
	if get_portmap; then
		echo "$(timestamp) | NAT-PMP/UPnP Ok!"
	else
		echo "$(timestamp) | NAT-PMP/UPnP Failed"
	fi
	# shellcheck disable=SC2086
	echo "$(timestamp) | Sleeping for $(echo ${CHECK_INTERVAL}/60 | bc) minutes"
	# shellcheck disable=SC2086
	sleep ${CHECK_INTERVAL}
done

exit $?