#!/bin/sh

. /lib/functions.sh

LOG="/usr/bin/logger -t $(basename "$0")[$$] -p"
INTERFACE=""
DEVICE=""

IFDOWN_EVENT=0

clean_up() {
	$LOG notice "Stopping mwan3track for interface \"${INTERFACE}\""
	rm "/var/run/mwan3track-${INTERFACE}.pid" &> /dev/null
	rm -rf "/var/run/mwan3track/${INTERFACE}" &> /dev/null
	if [ -z "$(ls -A "/var/run/mwan3track")" ]; then
		rm -rf "/var/run/mwan3track"
	fi
	exit 0
}

if_down() {
	$LOG info "Detect ifdown event on interface ${INTERFACE} (${DEVICE})"
	IFDOWN_EVENT=1
}

main() {
	local reliability count timeout interval failure_interval
	local recovery_interval down up size

	[ -z "$3" ] && echo "Error: should not be started manually" && exit 0

	INTERFACE=$1
	DEVICE=$2
	echo "$$" > /var/run/mwan3track-$1.pid
	mkdir -p /var/run/mwan3track/$1
	trap clean_up SIGINT SIGTERM
	trap if_down SIGUSR1

	config_load mwan3
	config_get reliability $1 reliability 1
	config_get count $1 count 1
	config_get timeout $1 timeout 4
	config_get interval $1 interval 10
	config_get down $1 down 5
	config_get up $1 up 5
	config_get size $1 size 56
	config_get failure_interval $1 failure_interval $interval
	config_get recovery_interval $1 recovery_interval $interval

	local score=$(($down+$up))
	local track_ips=$(echo $* | cut -d ' ' -f 3-99)
	local host_up_count=0
	local lost=0
	local sleep_time=0
	local turn=0

	echo "offline" > /var/run/mwan3track/$1/STATUS
	while true; do

		sleep_time=$interval

		for track_ip in $track_ips; do
			ping -I $2 -c $count -W $timeout -s $size -q $track_ip &> /dev/null
			if [ $? -eq 0 ]; then
				let host_up_count++
				echo "up" > /var/run/mwan3track/$1/TRACK_${track_ip}
			else
				let lost++
				echo "down" > /var/run/mwan3track/$1/TRACK_${track_ip}
			fi
		done

		if [ $host_up_count -lt $reliability ]; then
			let score--

			if [ $score -lt $up ]; then
				score=0
			else
				sleep_time=$failure_interval
			fi

			if [ $score -eq $up ]; then
				echo "offline" > /var/run/mwan3track/$1/STATUS
				$LOG notice "Interface $1 ($2) is offline"
				env -i ACTION=ifdown INTERFACE=$1 DEVICE=$2 /sbin/hotplug-call iface
				score=0
			fi
		else
			if [ $score -lt $(($down+$up)) ] && [ $lost -gt 0 ]; then
				$LOG info "Lost $(($lost*$count)) ping(s) on interface $1 ($2)"
			fi

			let score++
			lost=0

			if [ $score -gt $up ]; then
				echo "online" > /var/run/mwan3track/$1/STATUS
				score=$(($down+$up))
			elif [ $score -le $up ]; then
				sleep_time=$recovery_interval
			fi

			if [ $score -eq $up ]; then
				$LOG notice "Interface $1 ($2) is online"
				env -i ACTION=ifup INTERFACE=$1 DEVICE=$2 /sbin/hotplug-call iface
				rm /var/run/mwan3track-$1.pid
				rm -rf "/var/run/mwan3track/${1}" &> /dev/null
				exit 0
			fi
		fi

		let turn++
		echo "${lost}" > /var/run/mwan3track/$1/LOST
		echo "${score}" > /var/run/mwan3track/$1/SCORE
		echo "${turn}" > /var/run/mwan3track/$1/TURN

		host_up_count=0
		sleep "${sleep_time}" &
		wait

		if [ "${IFDOWN_EVENT}" -eq 1 ]; then
			score=0
			echo "offline" > /var/run/mwan3track/$1/STATUS
			IFDOWN_EVENT=0
		fi
	done
}

main "$@"