#!/bin/bash

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