#!/bin/bash

function isRoot() {
	if [ "$EUID" -ne 0 ]; then
		echo "You need to run this script as root"
		exit 1
	fi
}

function checkVirt() {
	if [ "$(systemd-detect-virt)" == "openvz" ]; then
		echo "OpenVZ is not supported"
		exit 1
	fi

	if [ "$(systemd-detect-virt)" == "lxc" ]; then
		echo "LXC is not supported (yet)."
		echo "WireGuard can technically run in an LXC container,"
		echo "but the kernel module has to be installed on the host,"
		echo "the container has to be run with some specific parameters"
		echo "and only the tools need to be installed in the container."
		exit 1
	fi
}

function checkOS() {
	# Check OS version
	if [[ -e /etc/debian_version ]]; then
		source /etc/os-release
		OS=$ID # debian or ubuntu
	elif [[ -e /etc/fedora-release ]]; then
		source /etc/os-release
		OS=$ID
	elif [[ -e /etc/centos-release ]]; then
		OS=centos
	elif [[ -e /etc/arch-release ]]; then
		OS=arch
	else
		echo "Looks like you aren't running this installer on a Debian, Ubuntu, Fedora, CentOS or Arch Linux system"
		exit 1
	fi
}

function initialCheck() {
	isRoot
	checkVirt
	checkOS
}

function installWireGuard() {

	# Detect public IPv4 address and pre-fill for the user
	SERVER_PUB_IPV4=$(ip addr | grep 'inet' | grep -v inet6 | grep -vE '127\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | grep -oE '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}' | head -1)
	read -rp "IPv4 or IPv6 public address: " -e -i "$SERVER_PUB_IPV4" SERVER_PUB_IP

	# Detect public interface and pre-fill for the user
	SERVER_PUB_NIC="$(ip -4 route ls | grep default | grep -Po '(?<=dev )(\S+)' | head -1)"
	read -rp "Public interface: " -e -i "$SERVER_PUB_NIC" SERVER_PUB_NIC

	SERVER_WG_NIC="wg0"
	read -rp "WireGuard interface name: " -e -i "$SERVER_WG_NIC" SERVER_WG_NIC

	SERVER_WG_IPV4="10.66.66.1"
	read -rp "Server's WireGuard IPv4: " -e -i "$SERVER_WG_IPV4" SERVER_WG_IPV4

	SERVER_WG_IPV6="fd42:42:42::1"
	read -rp "Server's WireGuard IPv6: " -e -i "$SERVER_WG_IPV6" SERVER_WG_IPV6

	# Generate random number within private ports range
	SERVER_PORT=$(shuf -i49152-65535 -n1)
	read -rp "Server's WireGuard port: " -e -i "$SERVER_PORT" SERVER_PORT

	# Install WireGuard tools and module
	if [[ $OS == 'ubuntu' ]]; then
		apt-get install -y software-properties-common
		add-apt-repository -y ppa:wireguard/wireguard
		apt-get update
		apt-get install -y "linux-headers-$(uname -r)"
		apt-get install -y wireguard iptables resolvconf qrencode
	elif [[ $OS == 'debian' ]]; then
		echo "deb http://deb.debian.org/debian/ unstable main" >/etc/apt/sources.list.d/unstable.list
		printf 'Package: *\nPin: release a=unstable\nPin-Priority: 90\n' >/etc/apt/preferences.d/limit-unstable
		apt update
		apt-get install -y "linux-headers-$(uname -r)"
		apt-get install -y wireguard iptables resolvconf qrencode
		apt-get install -y bc # mitigate https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=956869
	elif [[ $OS == 'fedora' ]]; then
		if [[ $VERSION_ID -lt 32 ]]; then
			dnf install -y dnf-plugins-core
			dnf copr enable -y jdoss/wireguard
			dnf install -y wireguard-dkms
		fi
		dnf install -y wireguard-tools iptables qrencode
	elif [[ $OS == 'centos' ]]; then
		curl -Lo /etc/yum.repos.d/wireguard.repo https://copr.fedorainfracloud.org/coprs/jdoss/wireguard/repo/epel-7/jdoss-wireguard-epel-7.repo
		yum -y install epel-release
		yum -y install wireguard-dkms wireguard-tools iptables qrencode
	elif [[ $OS == 'arch' ]]; then
		pacman -S --noconfirm linux-headers
		pacman -S --noconfirm wireguard-tools iptables qrencode
	fi

	# Make sure the directory exists (this does not seem the be the case on fedora)
	mkdir /etc/wireguard >/dev/null 2>&1

	chmod 600 -R /etc/wireguard/

	SERVER_PRIV_KEY=$(wg genkey)
	SERVER_PUB_KEY=$(echo "$SERVER_PRIV_KEY" | wg pubkey)

	# Save WireGuard settings
	echo "SERVER_PUB_IP=$SERVER_PUB_IP
SERVER_PUB_NIC=$SERVER_PUB_NIC
SERVER_WG_NIC=$SERVER_WG_NIC
SERVER_WG_IPV4=$SERVER_WG_IPV4
SERVER_WG_IPV6=$SERVER_WG_IPV6
SERVER_PORT=$SERVER_PORT
SERVER_PRIV_KEY=$SERVER_PRIV_KEY
SERVER_PUB_KEY=$SERVER_PUB_KEY" >/etc/wireguard/params

	# Add server interface
	echo "[Interface]
Address = $SERVER_WG_IPV4/24,$SERVER_WG_IPV6/64
ListenPort = $SERVER_PORT
PrivateKey = $SERVER_PRIV_KEY" >"/etc/wireguard/$SERVER_WG_NIC.conf"

	if [ -x "$(command -v firewall-cmd)" ]; then
		FIREWALLD_IPV4_ADDRESS=$(echo "$SERVER_WG_IPV4" | cut -d"." -f1-3)".0"
		FIREWALLD_IPV6_ADDRESS=$(echo "$SERVER_WG_IPV6" | sed 's/:[^:]*$/:0/')
		echo "PostUp = firewall-cmd --add-port $SERVER_PORT/udp && firewall-cmd --add-rich-rule='rule family=ipv4 source address=$FIREWALLD_IPV4_ADDRESS/24 masquerade' && firewall-cmd --add-rich-rule='rule family=ipv6 source address=$FIREWALLD_IPV6_ADDRESS/24 masquerade'
PostDown = firewall-cmd --remove-port $SERVER_PORT/udp && firewall-cmd --remove-rich-rule='rule family=ipv4 source address=$FIREWALLD_IPV4_ADDRESS/24 masquerade' && firewall-cmd --remove-rich-rule='rule family=ipv6 source address=$FIREWALLD_IPV6_ADDRESS/24 masquerade'" >>"/etc/wireguard/$SERVER_WG_NIC.conf"
	else
		echo "PostUp = iptables -A FORWARD -i $SERVER_WG_NIC -j ACCEPT; iptables -t nat -A POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE; ip6tables -A FORWARD -i $SERVER_WG_NIC -j ACCEPT; ip6tables -t nat -A POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE
PostDown = iptables -D FORWARD -i $SERVER_WG_NIC -j ACCEPT; iptables -t nat -D POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE; ip6tables -D FORWARD -i $SERVER_WG_NIC -j ACCEPT; ip6tables -t nat -D POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE" >>"/etc/wireguard/$SERVER_WG_NIC.conf"
	fi

	# Enable routing on the server
	echo "net.ipv4.ip_forward = 1
net.ipv6.conf.all.forwarding = 1" >/etc/sysctl.d/wg.conf

	sysctl --system

	systemctl start "wg-quick@$SERVER_WG_NIC"
	systemctl enable "wg-quick@$SERVER_WG_NIC"

	# Check if WireGuard is running
	systemctl is-active --quiet "wg-quick@$SERVER_WG_NIC"
	WG_RUNNING=$?

	# Warn user about kernel version mismatch with headers
	if [[ $OS =~ (fedora|centos) ]] && [[ $WG_RUNNING -ne 0 ]]; then
		echo -e "\nWARNING: WireGuard does not seem to be running."
		echo "Due to kernel mismatch issues on $OS, WireGuard might work if your system is out of date."
		echo "You can check if WireGuard is running with: systemctl status wg-quick@$SERVER_WG_NIC"
		echo 'If you get something like "Cannot find device wg0", please run:'
		if [[ $OS == 'fedora' ]]; then
			echo "dnf update -y && reboot"
		elif [[ $OS == 'centos' ]]; then
			echo "yum update -y && reboot"
		fi
	fi

	addClient
	echo "If you want to add more clients, you simply need to run this script another time!"
}

function addClient() {
	# Load params
	source /etc/wireguard/params

	if [[ $SERVER_PUB_IP =~ .*:.* ]]; then
		echo "IPv6 Detected"
		ENDPOINT="[$SERVER_PUB_IP]:$SERVER_PORT"
	else
		echo "IPv4 Detected"
		ENDPOINT="$SERVER_PUB_IP:$SERVER_PORT"
	fi

	CLIENT_WG_IPV4="10.66.66.2"
	read -rp "Client's WireGuard IPv4 " -e -i "$CLIENT_WG_IPV4" CLIENT_WG_IPV4

	CLIENT_WG_IPV6="fd42:42:42::2"
	read -rp "Client's WireGuard IPv6 " -e -i "$CLIENT_WG_IPV6" CLIENT_WG_IPV6

	# Adguard DNS by default
	CLIENT_DNS_1="176.103.130.130"
	read -rp "First DNS resolver to use for the client: " -e -i "$CLIENT_DNS_1" CLIENT_DNS_1

	CLIENT_DNS_2="176.103.130.131"
	read -rp "Second DNS resolver to use for the client: " -e -i "$CLIENT_DNS_2" CLIENT_DNS_2

	CLIENT_NAME=$(
		head /dev/urandom | tr -dc A-Za-z0-9 | head -c 10
		echo ''
	)

	# Generate key pair for the client
	CLIENT_PRIV_KEY=$(wg genkey)
	CLIENT_PUB_KEY=$(echo "$CLIENT_PRIV_KEY" | wg pubkey)
	CLIENT_PRE_SHARED_KEY=$(wg genpsk)

	# Create client file and add the server as a peer
	echo "[Interface]
PrivateKey = $CLIENT_PRIV_KEY
Address = $CLIENT_WG_IPV4/24,$CLIENT_WG_IPV6/64
DNS = $CLIENT_DNS_1,$CLIENT_DNS_2

[Peer]
PublicKey = $SERVER_PUB_KEY
PresharedKey = $CLIENT_PRE_SHARED_KEY
Endpoint = $ENDPOINT
AllowedIPs = 0.0.0.0/0,::/0" >>"$HOME/$SERVER_WG_NIC-client-$CLIENT_NAME.conf"

	# Add the client as a peer to the server
	echo -e "\n[Peer]
PublicKey = $CLIENT_PUB_KEY
PresharedKey = $CLIENT_PRE_SHARED_KEY
AllowedIPs = $CLIENT_WG_IPV4/32,$CLIENT_WG_IPV6/128" >>"/etc/wireguard/$SERVER_WG_NIC.conf"

	systemctl restart "wg-quick@$SERVER_WG_NIC"

	echo -e "\nHere is your client config file as a QR Code:"

	qrencode -t ansiutf8 -l L <"$HOME/$SERVER_WG_NIC-client-$CLIENT_NAME.conf"

	echo "It is also available in $HOME/$SERVER_WG_NIC-client-$CLIENT_NAME.conf"
}

function manageMenu() {
	echo "Welcome to WireGuard-install!"
	echo "The git repository is available at: https://github.com/angristan/wireguard-install"
	echo ""
	echo "It looks like WireGuard is already installed."
	echo ""
	echo "What do you want to do?"
	echo "   1) Add a new user"
	echo "   2) Exit"
	until [[ $MENU_OPTION =~ ^[1-2]$ ]]; do
		read -rp "Select an option [1-2]: " MENU_OPTION
	done
	case $MENU_OPTION in
	1)
		addClient
		;;
	2)
		exit 0
		;;
	esac
}

# Check for root, virt, OS...
initialCheck

# Check if WireGuard is already installed
if [[ -e /etc/wireguard/params ]]; then
	manageMenu
else
	installWireGuard
fi