#!/bin/sh /etc/rc.common
#
# Copyright (C) 2017 openwrt-ssr
# Copyright (C) 2017 yushi studio <ywb94@qq.com>
#
# This is free software, licensed under the GNU General Public License v3.
# See /LICENSE for more information.
#

LOCK_FILE="/var/lock/ssr-switch.lock"
[ -f "$LOCK_FILE" ] && exit 2
touch "$LOCK_FILE"
cycle_time=60
switch_time=3
normal_flag=0
server_locate=0
server_count=0
NAME=shadowsocksr
ENABLE_SERVER=nil
CONFIG_SWTICH_FILE=/var/etc/${NAME}_t.json

[ -n "$1" ] && cycle_time=$1
[ -n "$2" ] && switch_time=$2

uci_get_by_name() {
	local ret=$(uci get $NAME.$1.$2 2>/dev/null)
	echo ${ret:=$3}
}

uci_get_by_type() {
	local ret=$(uci get $NAME.@$1[0].$2 2>/dev/null)
	echo ${ret:=$3}
}

DEFAULT_SERVER=$(uci_get_by_type global global_server)
CURRENT_SERVER=$DEFAULT_SERVER

#解析ip
get_host_ip() {
	local host=$1
	local isip=""
	local ip=$host
	isip=$(echo $host | grep -E "([0-9]{1,3}[\.]){3}[0-9]{1,3}")
	if [ -z "$isip" ]; then
		if [ "$host" != "${host#*:[0-9a-fA-F]}" ]; then
			ip=$host
		else
			local ip=$(resolveip -4 -t 3 $host | awk 'NR==1{print}')
			[ -z "$ip" ] && ip=$(wget -q -O- http://119.29.29.29/d?dn=$1 | awk -F ';' '{print $1}')
		fi
	fi
	echo ${ip:="ERROR"}
}

#判断代理是否正常
check_proxy() {
	local result=0
	local try_count=$(uci_get_by_type global switch_try_count 3)
	for i in $(seq 1 $try_count); do
		/usr/bin/ssr-check www.google.com 80 $switch_time 1
		if [ "$?" == "0" ]; then
			# echo "$(date "+%Y-%m-%d %H:%M:%S") Check Google Proxy Success, count=$i" >> /tmp/ssrplus.log
			result=0
			break
		else
			# echo "$(date "+%Y-%m-%d %H:%M:%S") Check Google Proxy Fail, count=$i" >> /tmp/ssrplus.log
			/usr/bin/ssr-check www.baidu.com 80 $switch_time 1
			if [ "$?" == "0" ]; then
				result=1
			else
				result=2
			fi
		fi
		sleep 1
	done
	return $result
}

test_proxy() {
	local servername=$(get_host_ip $(uci_get_by_name $1 server))
	local serverport=$(uci_get_by_name $1 server_port)
	ipset add ss_spec_wan_ac $servername 2>/dev/null
	ret1=$?
	ret=$(tcpping -c 3 -p $serverport $servername | grep 'loss' | awk -F ',' '{ print $3 }' | awk -F "%" '{ print $1 }' | awk -F "." '{ print $1 }')
	#echo "$(date "+%Y-%m-%d %H:%M:%S") test_proxy> name: $servername, ret1: $ret1, ret: $ret" >> /tmp/ssrplus.log
	if [ -z "$ret" ] || [ "$ret" -gt "50" ]; then
		[ "$ret1" == "0" ] && ipset del ss_spec_wan_ac $servername 2>/dev/null
		return 1
	fi
	/usr/bin/ssr-check $servername $serverport $switch_time
	local ret2=$?
	[ "$ret1" == "0" ] && ipset del ss_spec_wan_ac $servername 2>/dev/null
	if [ "$ret2" == "0" ]; then
		return 0
	else
		return 1
	fi
}

search_proxy() {
	let server_count=server_count+1
	[ "$normal_flag" == "1" -a "$server_count" -le "$server_locate" ] && return 0
	[ "$(uci_get_by_name $1 switch_enable 0)" != "1" ] && return 1
	[ $ENABLE_SERVER != nil ] && return 0
	[ "$1" == "$CURRENT_SERVER" ] && return 0
	local servername=$(get_host_ip $(uci_get_by_name $1 server))
	local serverport=$(uci_get_by_name $1 server_port)
	ipset add ss_spec_wan_ac $servername 2>/dev/null
	ret=$?
	/usr/bin/ssr-check $servername $serverport $switch_time
	local ret2=$?
	[ "$ret" == "0" ] && ipset del ss_spec_wan_ac $servername 2>/dev/null
	if [ "$ret2" == "0" ]; then
		server_locate=$server_count
		ENABLE_SERVER=$1
		return 0
	else
		return 1
	fi
}

#选择可用的代理
select_proxy() {
	config_load $NAME
	ENABLE_SERVER=nil
	mkdir -p /var/run /var/etc
	server_count=0
	config_foreach search_proxy servers
}

#切换代理
switch_proxy() {
	/etc/init.d/shadowsocksr restart $1
	return 0
}

start() {
	#不支持kcptun启用时的切换
	[ $(uci_get_by_name $DEFAULT_SERVER kcp_enable) = "1" ] && return 1
	while [ "1" == "1" ]; do #死循环
		sleep $cycle_time
		LOGTIME=$(date "+%Y-%m-%d %H:%M:%S")
		#判断当前代理是否为缺省服务器
		if [ "$CURRENT_SERVER" != "$DEFAULT_SERVER" ]; then
			#echo "not default proxy"
			echo "$(date "+%Y-%m-%d %H:%M:%S") Current server is not default Main server, try to switch back." >>/tmp/ssrplus.log
			#检查缺省服务器是否正常
			if test_proxy $DEFAULT_SERVER; then
				#echo "switch to default proxy"
				echo "$(date "+%Y-%m-%d %H:%M:%S") Main server is avilable." >>/tmp/ssrplus.log
				#缺省服务器正常，切换回来
				CURRENT_SERVER=$DEFAULT_SERVER
				switch_proxy $CURRENT_SERVER
				echo "$(date "+%Y-%m-%d %H:%M:%S") switch to default "$(uci_get_by_name $CURRENT_SERVER alias)" proxy!" >>/tmp/ssrplus.log
			else
				echo "$(date "+%Y-%m-%d %H:%M:%S") Main server is NOT avilable.Continue using current server." >>/tmp/ssrplus.log
			fi
		fi
		#判断当前代理是否正常
		#echo "$(date "+%Y-%m-%d %H:%M:%S") Start checking if the current server is available." >>/tmp/ssrplus.log
		check_proxy
		current_ret=$?
		if [ "$current_ret" == "1" ]; then
			#当前代理错误，判断有无可用的服务器
			#echo "current error"
			echo "$(date "+%Y-%m-%d %H:%M:%S") Current server error, try to switch another server." >>/tmp/ssrplus.log
			select_proxy
			if [ "$ENABLE_SERVER" != nil ]; then
				#有其他服务器可用，进行切换
				#echo $(uci_get_by_name $new_proxy server)
				echo "$(date "+%Y-%m-%d %H:%M:%S") Another server is avilable, now switching server." >>/tmp/ssrplus.log
				CURRENT_SERVER=$ENABLE_SERVER
				switch_proxy $CURRENT_SERVER
				normal_flag=1
				echo "$(date "+%Y-%m-%d %H:%M:%S") Switch to "$(uci_get_by_name $CURRENT_SERVER alias)" proxy!" >>/tmp/ssrplus.log
			else
				switch_proxy $CURRENT_SERVER
				normal_flag=1
				echo "$(date "+%Y-%m-%d %H:%M:%S") Try restart current server." >>/tmp/ssrplus.log
			fi
		else
			normal_flag=0
			# echo "$(date "+%Y-%m-%d %H:%M:%S") ShadowsocksR No Problem." >>/tmp/ssrplus.log
		fi
	done
}