#!/bin/bash

rm -f variables.txt
echo -e "0\n0\n0\n0" > variables.txt
test -e users.txt || touch users.txt
test -p pipe || mkfifo pipe

port=1337

function setuser() {
	if [[ $(grep -En "^[^\:]*$1" users.txt) ]]; then
		echo "User already exists"
                sed -i "1s/.*/0/" variables.txt #status=0
                sed -i "2s/.*/0/" variables.txt #registerstatus=0
	else
		echo -n $1 >> users.txt
                echo -n ":" >> users.txt
                sed -i "2s/.*/1/" variables.txt #registerstatus=1
	fi
}

function setpassword() {
	hashedpw=$1
	n=$2
	echo -n $n >> users.txt
	echo -n ":" >> users.txt
	echo -n $hashedpw >> users.txt
	echo -n ":" >> users.txt
	echo "0" >> users.txt
}

function checkuser() {
	# check if user exists
	# send c in this function
	if [[ $(grep -En "^[^\:]*$1" users.txt) ]]; then
		LINE=$(grep -En "^[^\:]*$1" users.txt | cut -d ':' -f 1)
		N=$(grep -En "^[^\:]*$1" users.txt | cut -d ':' -f 3)
		sed -i "4s/.*/$LINE/" variables.txt
		sed -i "3s/.*/1/" variables.txt #loginstatus=1
		T=$(grep -En "^[^\:]*$1" users.txt | cut -d ':' -f 5)
		T=$(expr $T + 1)
		sed -i -e "${LINE}s/\:[^\:]*$//" users.txt
		sed -i -e "${LINE}s/$/:$T/" users.txt
		if [[ "$T" == "$N" ]]; then
			echo "USERACCEPTED $T no"
			sed -i "3s/.*/3/" variables.txt #loginstatus=3
		else
			echo "USERACCEPTED $T yes"
		fi
	else
		echo "User does not exist"
		sed -i "1s/.*/0/" variables.txt #status=0
                sed -i "3s/.*/0/" variables.txt #loginstatus=0
	fi
}

function checkpassword() {
	# checks if pw matches for given user
	newpw=$1
	passwd=$(echo $1 | shasum | cut -d ' ' -f 1)
	pwline=$(sed -n 4p variables.txt)
	realpw=$(sed -n ${pwline}p users.txt | cut -d ':' -f 3)
	if [[ "$passwd" == "$realpw" ]]; then
		sed -i "3s/.*/2/" variables.txt #loginstatus=2
		OLDT=$(sed -n ${pwline}p users.txt | cut -d ':' -f 4)
                sed -i -e "${LINE}s/\:[^\:]*$//" users.txt
		sed -i -e "${LINE}s/\:[^\:]*$//" users.txt
                sed -i -e "${LINE}s/$/:$newpw/" users.txt
		sed -i -e "${LINE}s/$/:$OLDT/" users.txt
		echo "PASSWORDACCEPTED yes"
	else
		 sed -i "3s/.*/0/" variables.txt #loginstatus=0
		 sed -i "1s/.*/0/" variables.txt #status=0
		echo "Wrong password!"
	fi
}

function test() {
	read input
	status=$(sed -n 1p variables.txt)
	registerstatus=$(sed -n 2p variables.txt)
	loginstatus=$(sed -n 3p variables.txt)
	if [[ "$status" == "0" ]]; then
		if [[ "$input" == "REGISTER" ]]; then
			sed -i "1s/.*/1/" variables.txt
		elif [[ "$input" == "LOGIN" ]]; then
			sed -i "1s/.*/2/" variables.txt
		else
			sed -i "1s/.*/0/" variables.txt
		fi
	elif [[ "$status" == "1" ]]; then
		if [[ "$registerstatus" == "0" ]]; then
			setuser $input
		elif [[ "$registerstatus" == "1" ]]; then
			setpassword $input
			sed -i "1s/.*/0/" variables.txt #status=0
			sed -i "2s/.*/0/" variables.txt #registerstatus=0
		else
			echo "impossible register else case"
		fi
	elif [[ "$status" == "2" ]]; then
		if [[ "$loginstatus" == "0" ]]; then
			checkuser $input
		elif [[ "$loginstatus" == "1" ]]; then
			checkpassword $input
		elif [[ "$loginstatus" == "2" ]]; then
			if [ ! -f $input ]; then
    				echo "File not found!"
			else
				echo $(cat $input)
			fi
			sed -i "1s/.*/0/" variables.txt #status=0
			sed -i "3s/.*/0/" variables.txt #loginstatus=0
		elif [[ "$loginstatus" == "3" ]]; then
			N=$(echo $input | cut -d ' ' -f 2)
			NEWPW=$(echo $input | cut -d ' ' -f 1)
			LINE=$(sed -n 4p variables.txt)
			sed -i -e "${LINE}s/\:[^\:]*$//" users.txt
                	sed -i -e "${LINE}s/\:[^\:]*$//" users.txt
			sed -i -e "${LINE}s/\:[^\:]*$//" users.txt
			sed -i -e "${LINE}s/$/:$N/" users.txt
                	sed -i -e "${LINE}s/$/:$NEWPW/" users.txt
                	sed -i -e "${LINE}s/$/:0/" users.txt
			sed -i "1s/.*/0/" variables.txt #status=0
                        sed -i "3s/.*/0/" variables.txt #loginstatus=0
		else
			echo "impossible login else case"
		fi
	else
		echo "impossible status else case"
	fi
}

while true;
do
	nc -l -p $port < pipe | test | cat > pipe;
done