#!/bin/bash
scriptName=$(basename $0)
version=0.1
idx=0
killFlag=0
localServiceIp="192.168.105.100"
remoteIp="172.26.123.156"
endpoint="192.168.105.100"
user="$USER"
cacheFile=.tunLast
privateKeyLoc="~/.ssh/id_ed25519"
override=0
debug=0
local="R"

fromPort=0
toPort=0
function killTunnel {
	if [[ debug -eq 1 ]]; then 
		printf "killTunnel %d\n" $toPort
	fi
	pkill -f "ssh -i ${privateKeyLoc} -fN${local} $toPort:"
}

function openTunnel {
	ssh -i ${privateKeyLoc} -fN${local} $toPort:${endpoint}:$fromPort ${user}@${remoteIp}
}

function parsePort {
	local delimiter=":"
	str=$1
	fromPort=${str%%${delimiter}*}
	toPort=${str#*${delimiter}}
	if [[ ${#toPort} -eq 0 ]]; then
		toPort=$fromPort
	fi
}

function usage {
	echo "
	Usage: $scriptName [OPTIONS]
	Options: 
	  -k | --kill		Try to kill defined tunnels, if missing will try to create them
	  -p | --port FROM:TO	Define new port forwarding rule, if in format FROM:TO - will create
	  			tunnel from port FROM on defined endpoint to port TO on local
	  -u | --user USERNAME  Define the user name on behalf of who will try to connect to remote target
	"
}

function about {
	echo "
	${scriptName} ver.${version} 
	Setup with next settings:
		started up under user: ${user}
		endpoint: ${endpoint}
		cacheFile: ${cacheFile}
	"
}

while [[ "$1" =~ ^- && ! "$1" == "--" ]]; do case $1 in
  -a | --about )
    about
    exit
    ;;
  -u | --user )
    shift;
    user=$1
    ;;
  -l | --local )
	local="L"
	remoteIp="localhost"
	;;
  -k | --kill )
    killFlag=1
    ;;
  -p | --port )
    shift;
    port[$idx]=$1
    idx=$(($idx+1))
    override=1
    ;;
  -d | --debug )
    debug=1
    ;;
  -h | --help )
    usage
    exit
    ;;
esac; shift; done
if [[ "$1" == '--' ]]; then shift; fi

if [[ ${debug} -eq 1 ]]; then
	about
fi

if [[ ${#port[@]} -gt 0 ]]; then
	printf "PORT TO OPEN: %s\n" ${port[@]}
fi

if [[ ${override} -eq 0 && -r ${cacheFile} ]]; then
	while IFS= read -r line; do
    	port[$idx]=$line
	idx=$(($idx+1))
	done < ${cacheFile}
fi

for i in "${port[@]}"; do
	parsePort $i
	if [[ ${killFlag} -eq 1 ]]; then
		killTunnel 
	else
		openTunnel 
	fi
done

printf "%s\\n" "${port[@]}" > ${cacheFile}

if [[ ${debug} -eq 1 ]]; then
	ps aux | grep "ssh -i ${privateKeyLoc}" | grep -v grep
fi