#!/bin/bash

# Use systemd-networkd instead of dhcpcd as the DHCP client for Raspberry Pi OS
# remember to use wpa_passphrase to add SSID & PW to /etc/wpa_supplicant/wpa_supplicant.conf

# checking sudo privilege

if [[ "$EUID" -ne 0 ]]; then
  echo "This script must be run as root" 1>&2   # redirect stdout to stderr
  exit 1
fi

###systemd-resolved###
mv /etc/resolv.conf /etc/resolv.conf.bak
ln -sf ../run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

mkdir -p /etc/systemd/network

############################
cat << EOF > /etc/systemd/network/20-eth.network
[Match]
Name=eth*

[Network]
DHCP=true
IPv6AcceptRA=true

[DHCPv4]
RouteMetric=20
ClientIdentifier=mac
UseDomains=true

[IPv6AcceptRA]
RouteMetric=20
EOF

##########
cat << EOF > /etc/systemd/network/30-wlan.network
[Match]
Name=wlan*

[Network]
DHCP=true
IPv6AcceptRA=true

[DHCPv4]
RouteMetric=30
ClientIdentifier=mac
UseDomains=true

[IPv6AcceptRA]
RouteMetric=30
EOF
#############################

#cp /lib/systemd/system/systemd-networkd-wait-online.service /lib/systemd/system/systemd-networkd-wait-online.service.bak
#sed -i 's/systemd-networkd-wait-online$/systemd-networkd-wait-online --any/' /lib/systemd/system/systemd-networkd-wait-online.service

####### override systemd-networkd-wait-online to avoid startup delay and retain this config after systemd upgrade
mkdir -p /etc/systemd/system/systemd-networkd-wait-online.service.d

cat << EOF > /etc/systemd/system/systemd-networkd-wait-online.service.d/wait-for-only-one-interface.conf
[Service]
ExecStart=
ExecStart=/usr/lib/systemd/systemd-networkd-wait-online --any
EOF
########

####wireless####
# https://wiki.archlinux.org/title/wpa_supplicant#At_boot_(systemd)
ln -s /etc/wpa_supplicant/wpa_supplicant.conf /etc/wpa_supplicant/wpa_supplicant-wlan0.conf

####sytstem services####
systemctl disable --now dhcpcd
systemctl enable --now systemd-networkd systemd-resolved wpa_supplicant@wlan0