#!/bin/bash

if [ "$EUID" -ne 0 ]; then
    echo "You need to run this script as root"
    exit 1
fi

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

# 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

SERVER_PORT=1194
read -rp "Server's WireGuard port " -e -i "$SERVER_PORT" SERVER_PORT

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

# Install WireGuard on Ubuntu
add-apt-repository -y ppa:wireguard/wireguard
apt-get install -y wireguard

# Generate key pair for the server
SERVER_PRIV_KEY=$(wg genkey)
SERVER_PUB_KEY=$(echo "$SERVER_PRIV_KEY" | wg pubkey)

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

# Add server interface
echo "[Interface]
Address = $SERVER_WG_IPV4/24,$SERVER_WG_IPV6/64
ListenPort = $SERVER_PORT
PrivateKey = $SERVER_PRIV_KEY
PostUp = iptables -t nat -A POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE; ip6tables -t nat -A POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE
PostDown = iptables -t nat -D POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE; ip6tables -t nat -D POSTROUTING -o $SERVER_PUB_NIC -j MASQUERADE" > "/etc/wireguard/$SERVER_WG_NIC.conf"

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

# Create client file with interface
echo "[Interface]
PrivateKey = $CLIENT_PRIV_KEY
Address = $CLIENT_IPV4/24,$CLIENT_IPV6/64
DNS = $CLIENT_DNS_1,$CLIENT_DNS_2" > "$HOME/$SERVER_WG_NIC-client.conf"

# Add the server as a peer to the client
echo "[Peer]
PublicKey = $SERVER_PUB_KEY
Endpoint = $SERVER_PUB_IP:1194
AllowedIPs = 0.0.0.0/0,::/0" >> "$HOME/$SERVER_WG_NIC-client.conf"

# 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"