#!/usr/bin/env bash
# Dynamic login banner. Installed to /etc/update-motd.d/ (executable) or
# rendered once into /etc/motd as a fallback. Keep it fast & dependency-free.

# --- colors (only if stdout is a tty; motd.d output is captured, so keep plain)
B=$'\e[1m'; D=$'\e[2m'; G=$'\e[32m'; Y=$'\e[33m'; R=$'\e[31m'; C=$'\e[36m'; N=$'\e[0m'

host="$(hostname -f 2>/dev/null || hostname)"
os="$(. /etc/os-release 2>/dev/null && echo "${PRETTY_NAME:-Linux}")"
kern="$(uname -r)"
up="$(uptime -p 2>/dev/null | sed 's/^up //')"
load="$(cut -d' ' -f1-3 /proc/loadavg 2>/dev/null)"
ipaddr="$(ip -4 route get 1.1.1.1 2>/dev/null | awk '{print $7; exit}')"
[ -z "$ipaddr" ] && ipaddr="n/a"

# memory + disk (root fs)
mem="$(free -h 2>/dev/null | awk '/^Mem:/ {print $3 "/" $2}')"
disk="$(df -h / 2>/dev/null | awk 'NR==2 {print $3 "/" $2 " (" $5 ")"}')"

# pending updates (apt) + reboot flag - cheap checks, ignore errors
updates=""
if [ -r /var/lib/update-notifier/updates-available ]; then
  updates="$(awk 'NR==1{print}' /var/lib/update-notifier/updates-available 2>/dev/null)"
fi
reboot_flag=""
[ -f /var/run/reboot-required ] && reboot_flag="${R}  reboot required${N}"

# load colorization
load1="${load%% *}"
lc="$G"
awk "BEGIN{exit !($load1 > 2.0)}" && lc="$Y"
awk "BEGIN{exit !($load1 > 4.0)}" && lc="$R"

printf '\n'
printf '  %s%s%s\n' "$B$C" "$host" "$N"
printf '  %s%s%s\n' "$D" "$os · kernel $kern" "$N"
printf '\n'
printf '   %sIP%s     %s\n'      "$D" "$N" "$ipaddr"
printf '   %sUptime%s %s   %sload%s %s%s%s\n' "$D" "$N" "${up:-n/a}" "$D" "$N" "$lc" "$load" "$N"
printf '   %sMem%s    %s   %sdisk /%s %s\n'   "$D" "$N" "${mem:-n/a}" "$D" "$N" "${disk:-n/a}"
[ -n "$updates" ]     && printf '   %sUpdates%s %s\n' "$D" "$N" "$updates"
[ -n "$reboot_flag" ] && printf '  %s\n' "$reboot_flag"
printf '\n'