#!/bin/bash

# Usage : parseConf $fileContent $propertyName
# Retrieves the value of propertyName from fileContent
# And echoes it back
function parseConf() {
	result=$(echo "$1" | grep $2 | cut -f2 -d'=')
	echo $result
}


if [ $EUID -ne 0 ]; then
	echo "This script can only be run as root"
	exit -1
fi

if [ "$1" = "--help" ] || [ "$1" = "-h" ]; then
	cat <<EOF 
This script adds a peer to a Wireguard configuration and
outputs the corresponding configuration file.

Usage : 
$0 [ PATH_TO_WIREGUARD_CONFIGURATIONS ]

EOF

	exit 0
fi

configurationsPath="/etc/wireguard"
if [ -d "$1" ]; then
	configurationsPath="$1"
fi

# Retrieve every configuration file using a glob.
# Don't add anything to the array if nothing is present
shopt -s nullglob
wireguardConfigs=(/etc/wireguard/*)
shopt -u nullglob

configCount=${#wireguardConfigs[@]}

if [ $configCount -eq 0 ]; then
	echo "There are no wireguard configs availabe !"
	exit -1
fi

count=0
echo "Available configurations :"
for configuration in ${wireguardConfigs[@]}; do
	echo -e "\t"$count. "$configuration"
	count=$(($count+1))
done

invalid=true
while $invalid; do
	echo -n "Please choose a configuration: "
	read choice
	echo ""

	case $choice in
		[0-$(($configCount-1))])
			invalid=false
		;;
		'')
			echo "Exiting"
			exit 0
		;;
		*)
			echo "Invalid argument, please use the numbers printed before the configurations"
		;;
	esac
done


confFile=${wireguardConfigs[$choice]}
echo "Using $confFile"


fileContent="$(cat $confFile)"

listenPort=$(parseConf "$fileContent" ListenPort)
address=$(parseConf "$fileContent" Address)
targetDomain=$(echo $(ip -4 -resolve -brief addr show | grep UP) | cut -f3 -d' ' | cut -f1 -d'/')
# Manually add '=' as we cut with delimiter '='
pubKey=$(echo $(parseConf "$fileContent" PrivateKey)= | wg pubkey)


echo -n "Server address is $address, please enter peer address: "
read peerAddress

echo -n "Please enter allowed IPs range for peer: "
read peerAllowedIPs

peerKey=$(wg genkey)
peerPubKey=$(echo $peerKey | wg pubkey)

cat <<EOF >> $confFile

[Peer]
PublicKey = $peerPubKey
AllowedIPs = $peerAddress/32

EOF

cat <<EOF
[Interface]
Address = $peerAddress/$(echo $address | cut -f2 -d'/')
PrivateKey = $peerKey

[Peer]
PublicKey = $pubKey
AllowedIPs = $peerAllowedIPs
Endpoint = $targetDomain:$listenPort


EOF