#!/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 "Host identity"
if command -v hostnamectl >/dev/null 2>&1; then
  run_optional "hostnamectl" hostnamectl
else
  run_optional "hostname" hostname
fi
run_optional "kernel information" uname -a
run_optional "uptime" uptime

section "Memory"
if command -v free >/dev/null 2>&1; then
  run_optional "memory report" free -h
else
  printf 'WARNING: free is not available\n'
fi

section "Filesystems"
if command -v df >/dev/null 2>&1; then
  run_optional "filesystem report" df -hT
  printf '\nKey mountpoints present:\n'
  for mountpoint in / /boot /var /srv /opt /home; do
    if findmnt -rn --target "$mountpoint" >/dev/null 2>&1; then
      run_optional "filesystem report for $mountpoint" df -hT "$mountpoint"
    fi
  done
else
  printf 'WARNING: df is not available\n'
fi

section "Journal usage"
if command -v journalctl >/dev/null 2>&1; then
  run_optional "journal disk usage" journalctl --disk-usage
else
  printf 'WARNING: journalctl is not available\n'
fi

section "Docker"
if command -v docker >/dev/null 2>&1; then
  if command -v systemctl >/dev/null 2>&1; then
    run_optional "Docker service state" systemctl is-active docker
  fi
  run_optional "Docker container list" docker ps --format 'table {{.Names}}\t{{.Image}}\t{{.Status}}\t{{.Ports}}'
  run_optional "Docker disk usage" docker system df
else
  printf 'INFO: Docker is not installed\n'
fi

section "Libvirt"
if command -v virsh >/dev/null 2>&1; then
  if command -v systemctl >/dev/null 2>&1; then
    run_optional "libvirtd service state" systemctl is-active libvirtd
  fi
  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 "Failed systemd units"
if command -v systemctl >/dev/null 2>&1; then
  run_optional "failed systemd unit report" systemctl --failed --no-pager
else
  printf 'WARNING: systemctl is not available\n'
fi

section "SMART quick health"
if command -v smartctl >/dev/null 2>&1; then
  shopt -s nullglob
  devices=(/dev/sd? /dev/nvme?n?)
  shopt -u nullglob

  if ((${#devices[@]} == 0)); then
    printf 'INFO: no matching SATA/SCSI or NVMe devices found\n'
  else
    for device in "${devices[@]}"; do
      printf '\n-- %s --\n' "$device"
      run_optional "SMART health check for $device" smartctl -H "$device"
    done
  fi
else
  printf 'INFO: smartctl is not installed\n'
fi

exit 0