#!/usr/bin/env zsh
#
# find_systems.zsh
# Sweeps a subnet for hosts with SSH open, then queries each as `kiosk`
# for hostname + NixOS configuration revision.
#
# Usage: ./find_systems.zsh [subnet]
#   subnet defaults to 192.168.4.0/24

set -uo pipefail # no -e: we want to keep going past unreachable hosts

SUBNET="${1:-192.168.4.0/24}"
SSH_USER="kiosk"
SSH_OPTS=(-o BatchMode=yes -o ConnectTimeout=5 -o StrictHostKeyChecking=accept-new)

echo "Scanning $SUBNET for open SSH (22)..."
ips=("${(@f)$(nmap -p 22 --open -Pn "$SUBNET" -oG - | awk '/22\/open/ {print $2}')}")

if [[ ${#ips[@]} -eq 0 ]]; then
  echo "No hosts with open SSH found on $SUBNET."
  exit 0
fi

echo "Found ${#ips[@]} host(s). Querying..."
echo

fail_count=0

for ip in "${ips[@]}"; do
  echo "== $ip =="
  if ssh "${SSH_OPTS[@]}" "${SSH_USER}@${ip}" \
    'echo "host: $(hostname)"; echo "rev:  $(nixos-version --configuration-revision)"'; then
    :
  else
    echo "  (unreachable or auth failed)"
    ((fail_count++))
  fi
  echo
done

echo "Done. ${fail_count} of ${#ips[@]} host(s) failed to respond."