#!/usr/bin/env bash
set -o errexit
set -o nounset
set -o pipefail

section() {
  printf '\n== %s ==\n' "$1"
}

run_optional() {
  local description="$1"
  shift

  if "$@"; then
    return 0
  fi
  printf 'WARNING: %s failed\n' "$description"
  return 0
}

section "Failed systemd units"
if command -v systemctl >/dev/null 2>&1; then
  run_optional "failed systemd unit report" systemctl --failed --no-pager

  section "Selected service status"
  for unit in cockpit.socket docker.service libvirtd.service fail2ban.service; do
    if systemctl cat "$unit" >/dev/null 2>&1; then
      run_optional "$unit status" systemctl status "$unit" --no-pager
    else
      printf 'INFO: %s is not installed\n' "$unit"
    fi
  done
else
  printf 'WARNING: systemctl is unavailable\n'
fi

section "Docker"
if command -v docker >/dev/null 2>&1; then
  run_optional "Docker container list" docker ps
else
  printf 'INFO: Docker is not installed\n'
fi

section "Libvirt"
if command -v virsh >/dev/null 2>&1; then
  run_optional "libvirt guest list" virsh list --all
else
  printf 'INFO: virsh is not installed\n'
fi

section "NVIDIA"
if command -v nvidia-smi >/dev/null 2>&1; then
  run_optional "NVIDIA status" nvidia-smi
else
  printf 'INFO: nvidia-smi is not installed\n'
fi

section "Filesystems"
run_optional "filesystem report" df -hT

section "Listening ports"
if command -v ss >/dev/null 2>&1; then
  run_optional "listening port report" ss -tulpn
else
  printf 'WARNING: ss is unavailable\n'
fi

printf '\nOK: postcheck completed; review warnings above\n'
exit 0