#!/bin/bash

# Avoid unnecessary reboots: don't notify if an updated package is
# - not currently running (e.g. alternative kernel)
# - not in use (e.g. alternative driver)

## Colors ----------------------------

# Reset
Color_Off='\033[0m'       # Text Reset

# Regular Colors
Black='\033[0;30m'  Red='\033[0;31m'     Green='\033[0;32m'  Yellow='\033[0;33m'
Blue='\033[0;34m'   Purple='\033[0;35m'  Cyan='\033[0;36m'   White='\033[0;37m'

# Bold
BBlack='\033[1;30m' BRed='\033[1;31m'    BGreen='\033[1;32m' BYellow='\033[1;33m'
BBlue='\033[1;34m'  BPurple='\033[1;35m' BCyan='\033[1;36m'  BWhite='\033[1;37m'

## -----------------------------------

_notify_reboot_required() {
    local xx

    for xx in "$DESKTOP_SESSION" "$XDG_CURRENT_DESKTOP"; do
      if [[ -n "$xx" ]]; then
        break
      fi
    done

    if [[ -n "$xx" ]]; then
      local user userid cmd
      for user in $(/usr/bin/users); do
        userid=$(/usr/bin/id -u $user)
        cmd=(DISPLAY=:0 DBUS_SESSION_ADDRESS=unix:path=/run/user/$userid/bus /usr/bin/notify-send)
        cmd+=(--icon=system-reboot --urgency=critical)
        cmd+=("\"Core system package upgraded, You need to reboot the machine.\"")
        /usr/bin/su $user -c "${cmd[*]}"
      done
    else
      # at TTY
      echo -e ${BRed}"\n[*] Core system package upgraded, You need to reboot the machine.\n"${Color_Off} >&2
    fi

}

RunningKernel() {
  cat /proc/cmdline | sed 's|.*/vmlinuz-\(linux[a-z0-9-]*\) .*|\1|'
}

main() {
  # targets from the hook (stdin) #
  local targets=$(tee /dev/null)
  local target
  local notify=no
  local runningKernel="$(RunningKernel)"

  for target in $targets; do
    case "$target" in
        linux | linux-lts | linux-zen | linux-hardened | linux-lts?? | linux-lts???)
          # Note: only official and older LTS kernels are checked.
          if [[ "$target" = "$runningKernel" ]] ; then
            notify=yes
            break
          fi
          ;;
        btrfs-progs)
          if [[ -n "$(/usr/bin/df -hT | awk '{print $2}' | grep -w btrfs)" ]] ; then
            notify=yes
            break
          fi
          ;;
        *)
          notify=yes
          break
          ;;
    esac
  done

  if [[ "$notify" = "yes" ]]; then
    _notify_reboot_required
    unset -f _notify_reboot_required
  fi
}

main "$@"