#!/bin/sh

. /lib/functions.sh
. /lib/mwan3/common.sh

INTERFACE=""
DEVICE=""
PING="/bin/ping"

IFDOWN_EVENT=0
IFUP_EVENT=0

clean_up() {
	LOG notice "Stopping mwan3track for interface \"${INTERFACE}\""
	exit 0
}

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

if_up() {
	LOG info "Detect ifup event on interface ${INTERFACE} (${DEVICE})"
	IFUP_EVENT=1
}

validate_track_method() {
	case "$1" in
		ping)
			[ -x "$PING" ] || {
				LOG warn "Missing ping. Please enable ping util and recompile busybox."
				return 1
			}
			;;
		arping)
			command -v arping 1>/dev/null 2>&1 || {
				LOG warn "Missing arping. Please install iputils-arping package."
				return 1
			}
			;;
		httping)
			command -v httping 1>/dev/null 2>&1 || {
				LOG warn "Missing httping. Please install httping package."
				return 1
			}
			[ -n "$2" -a "$2" != "0.0.0.0" -a "$2" != "::" ] || {
				LOG warn "Cannot determine source IP for the interface which is required by httping."
				return 1
			}
			;;
		nping-*)
			command -v nping 1>/dev/null 2>&1 || {
				LOG warn "Missing nping. Please install nping package."
				return 1
			}
			;;
		*)
			LOG warn "Unsupported tracking method: $track_method"
			return 2
			;;
	esac
}

disconnected() {
	echo "offline" > /var/run/mwan3track/$INTERFACE/STATUS
	echo "$(get_uptime)" > /var/run/mwan3track/$INTERFACE/OFFLINE
	echo "0" > /var/run/mwan3track/$INTERFACE/ONLINE
	score=0
	[ "$1" == 1 ] && return
	LOG notice "Interface $INTERFACE ($DEVICE) is offline"
	env -i ACTION="disconnected" INTERFACE="$INTERFACE" DEVICE="$DEVICE" /sbin/hotplug-call iface
}

connected() {
	echo "online" > /var/run/mwan3track/$INTERFACE/STATUS
	echo "0" > /var/run/mwan3track/$INTERFACE/OFFLINE
	echo "$(get_uptime)" > /var/run/mwan3track/$INTERFACE/ONLINE
	host_up_count=0
	lost=0
	turn=0
	loss=0
	[ "$1" == 1 ] && return
	LOG notice "Interface $INTERFACE ($DEVICE) is online"
	env -i ACTION="connected" INTERFACE="$INTERFACE" DEVICE="$DEVICE" /sbin/hotplug-call iface
}

firstconnect() {
	if [ "$STATUS" = "offline" ]; then
		disconnected 1
	else
		connected 1
	fi
}

update_status() {
	local status track_ip
	track_ip=$1
	status=$2

	echo "$1" > /var/run/mwan3track/$INTERFACE/TRACK_${track_ip}
	[ -z "$3" ] && return
	echo "$3" > /var/run/mwan3track/$INTERFACE/LATENCY_${track_ip}
	echo "$4" > /var/run/mwan3track/$INTERFACE/LOSS_${track_ip}
}

main() {
	local reliability count timeout interval failure_interval
	local recovery_interval down up size
	local keep_failure_interval check_quality failure_latency
	local recovery_latency failure_loss recovery_loss
	local max_ttl httping_ssl

	[ -z "$5" ] && echo "Error: should not be started manually" && exit 0

	INTERFACE=$1
	DEVICE=$2
	STATUS=$3
	SRC_IP=$4
	mkdir -p /var/run/mwan3track/$INTERFACE
	trap clean_up TERM
	trap if_down USR1
	trap if_up USR2

	config_load mwan3
	config_get track_method $INTERFACE track_method ping
	config_get_bool httping_ssl $INTERFACE httping_ssl 0
	validate_track_method $track_method $SRC_IP || {
		track_method=ping
		if validate_track_method $track_method; then
			LOG warn "Using ping to track interface $INTERFACE avaliability"
		else
			LOG err "No track method avaliable"
			exit 1
		fi
	}
	config_get reliability $INTERFACE reliability 1
	config_get count $INTERFACE count 1
	config_get timeout $INTERFACE timeout 4
	config_get interval $INTERFACE interval 10
	config_get down $INTERFACE down 5
	config_get up $INTERFACE up 5
	config_get size $INTERFACE size 56
	config_get max_ttl $INTERFACE max_ttl 60
	config_get failure_interval $INTERFACE failure_interval $interval
	config_get_bool keep_failure_interval $INTERFACE keep_failure_interval 0
	config_get recovery_interval $INTERFACE recovery_interval $interval
	config_get_bool check_quality $INTERFACE check_quality 0
	config_get failure_latency $INTERFACE failure_latency 1000
	config_get recovery_latency $INTERFACE recovery_latency 500
	config_get failure_loss $INTERFACE failure_loss 40
	config_get recovery_loss $INTERFACE recovery_loss 10

	local score=$(($down+$up))
	local track_ips=$(echo $* | cut -d ' ' -f 5-99)
	local host_up_count=0
	local lost=0
	local turn=0
	local ping_protocol=4
	local sleep_time result ping_result ping_result_raw  ping_status loss latency

	firstconnect
	while true; do

		sleep_time=$interval

		for track_ip in $track_ips; do
			if [ $host_up_count -lt $reliability ]; then
				case "$track_method" in
					ping)
						# pinging IPv6 hosts with an interface is troublesome
						# https://bugs.openwrt.org/index.php?do=details&task_id=2897
						# so get the IP address of the interface and use that instead
						if [ -z ${track_ip##*:*} ]; then
							ping_protocol=6
						else
							unset SRC_IP
						fi
						if [ $check_quality -eq 0 ]; then
							$PING -$ping_protocol -I ${SRC_IP:-$DEVICE} -c $count -W $timeout -s $size -t $max_ttl -q $track_ip &> /dev/null
							result=$?
						else
							ping_result_raw="$($PING -$ping_protocol -I ${SRC_IP:-$DEVICE} -c $count -W $timeout -s $size -t $max_ttl -q $track_ip 2>/dev/null)"
							ping_status=$?
							ping_result=$(echo "$ping_result_raw" | tail -n2)
							loss="$(echo "$ping_result" | grep "packet loss" |  cut -d "," -f3 | awk '{print $1}' | sed -e 's/%//')"
							if [ "$ping_status" -ne 0 ] || [ "$loss" -eq 100 ]; then
								latency=999999
								loss=100
							else
								latency="$(echo "$ping_result" | grep -E 'rtt|round-trip' | cut -d "=" -f2 | cut -d "/" -f2 | cut -d "." -f1)"
							fi
						fi
					;;
					arping)
						arping -I $DEVICE -c $count -w $timeout -q $track_ip &> /dev/null
						result=$?
					;;
					httping)
						if [ "$httping_ssl" -eq 1 ]; then
							httping -y $SRC_IP -c $count -t $timeout -q "https://$track_ip" &> /dev/null
						else
							httping -y $SRC_IP -c $count -t $timeout -q "http://$track_ip" &> /dev/null
						fi
						result=$?
					;;
					nping-tcp)
						result=$(nping -e $DEVICE -c $count $track_ip --tcp | grep Lost | awk '{print $12}')
					;;
					nping-udp)
						result=$(nping -e $DEVICE -c $count $track_ip --udp | grep Lost | awk '{print $12}')
					;;
					nping-icmp)
						result=$(nping -e $DEVICE -c $count $track_ip --icmp | grep Lost | awk '{print $12}')
					;;
					nping-arp)
						result=$(nping -e $DEVICE -c $count $track_ip --arp | grep Lost | awk '{print $12}')
					;;
				esac
				if [ $check_quality -eq 0 ]; then
					if [ $result -eq 0 ]; then
						let host_up_count++
						update_status "$track_ip" "up"

						if [ $score -le $up ]; then
							LOG info "Check ($track_method) success for target \"$track_ip\" on interface $INTERFACE ($DEVICE). Current score: $score"
						fi
					else
						let lost++
						update_status "$track_ip" "down"

						if [ $score -gt $up ]; then
							LOG info "Check ($track_method) failed for target \"$track_ip\" on interface $INTERFACE ($DEVICE). Current score: $score"
						fi
					fi
				else
					if [ "$loss" -ge "$failure_loss" -o "$latency" -ge "$failure_latency" ]; then
						let lost++
						update_status "$track_ip" "down" $latency $loss

						if [ $score -gt $up ]; then
							LOG info "Check (${track_method}: latency=${latency}ms loss=${loss}%) failed for target \"$track_ip\" on interface $INTERFACE ($DEVICE). Current score: $score"
						fi
					elif [ "$loss" -le "$recovery_loss" -a "$latency" -le "$recovery_latency" ]; then
						let host_up_count++
						update_status "$track_ip" "up" $latency $loss

						if [ $score -le $up ]; then
							LOG info "Check (${track_method}: latency=${latency}ms loss=${loss}%) success for target \"$track_ip\" on interface $INTERFACE ($DEVICE). Current score: $score"
						fi
					else
						echo "skipped" > /var/run/mwan3track/$INTERFACE/TRACK_${track_ip}
					fi
				fi
			else
				echo "skipped" > /var/run/mwan3track/$INTERFACE/TRACK_${track_ip}
			fi
		done

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

			if [ $score -lt $up ]; then
				score=0
				[ ${keep_failure_interval} -eq 1 ] && {
					sleep_time=$failure_interval
				}
			else
				sleep_time=$failure_interval
			fi

			if [ $score -eq $up ]; then
				disconnected
				score=0
			fi
		else
			if [ $score -lt $(($down+$up)) ] && [ $lost -gt 0 ]; then
				LOG info "Lost $(($lost*$count)) ping(s) on interface $INTERFACE ($DEVICE). Current score: $score"
			fi

			let score++
			lost=0

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

			if [ $score -eq $up ]; then
				connected $INTERFACE $DEVICE
			fi
		fi

		let turn++
		mkdir -p "/var/run/mwan3track/${1}"
		echo "${lost}" > /var/run/mwan3track/$INTERFACE/LOST
		echo "${score}" > /var/run/mwan3track/$INTERFACE/SCORE
		echo "${turn}" > /var/run/mwan3track/$INTERFACE/TURN
		echo "$(get_uptime)" > /var/run/mwan3track/$INTERFACE/TIME

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

		if [ "${IFDOWN_EVENT}" -eq 1 ]; then
			LOG debug "Register ifdown event on interface ${INTERFACE} (${DEVICE})"
			disconnected 1
			IFDOWN_EVENT=0
		fi
		if [ "${IFUP_EVENT}" -eq 1 ]; then
			LOG debug "Register ifup event on interface ${INTERFACE} (${DEVICE})"
			firstconnect
			IFUP_EVENT=0
		fi
	done
}

main "$@"