#!/bin/sh

usage() {
    echo "Usage: vpn-client.sh <hostname>"
    echo "hostname: Name of the new host"
    exit 1
}

get_last_ip() {
    last_ocurrence=$(grep '10.9.0' "$networking_file" | tail -1)
    last_digit=$(echo "$last_ocurrence" | cut -d . -f 4 | cut -c 1)
}

generate_certificates() {
    mkdir "$certificates_directory/$hostname"
    cd "$certificates_directory/$hostname" || exit
    wg genkey | tee "$hostname".key | wg pubkey >"$hostname".pub
}

generate_config() {
    private_key=$(cat "$hostname.key")
    get_last_ip
    last_ip=$((last_digit + 1))
    cd "$config_directory" || exit
    sed -e "s/private_key_placeholder/$private_key/g" -e "s/ip_placeholder/$last_ip/g" "$config_file" >"$hostname".conf
}

if [ $# != 1 ]; then
    usage
fi

hostname=$1
networking_file="/etc/nixos/modules/networking.nix"
certificates_directory="/home/coace/.wg"
config_directory="/vault/config/wireguard"
config_file="$config_directory/placeholder.conf"

generate_certificates
generate_config