#!/usr/bin/env zsh
  
  ## setup ##
  
  [[ -o interactive ]] || return #interactive only!
  zmodload zsh/datetime || { print "can't load zsh/datetime"; return } # faster than date()
  autoload -Uz add-zsh-hook || { print "can't add zsh hook!"; return }
  
  (( ${+bgnotify_threshold} )) || bgnotify_threshold=5 #default 10 seconds
  
  
  ## definitions ##
  
  if ! (type bgnotify_formatted | grep -q 'function'); then
    function bgnotify_formatted {
      ## exit_status, command, elapsed_time
      [ $1 -eq 0 ] && title="#win (took $3 s)" || title="#fail (took $3 s)"
      bgnotify "$title" "$2"
    }
  fi
  
  currentWindowId () {
    if hash osascript 2>/dev/null; then #osx
      osascript -e 'tell application (path to frontmost application as text) to id of front window' 2&> /dev/null || echo "0"
    elif hash notify-send 2>/dev/null; then #ubuntu!
      xprop -root | awk '/NET_ACTIVE_WINDOW/ { print $5; exit }'
    else
      echo $EPOCHSECONDS #fallback for windows
    fi
  }
  
  bgnotify () {
    if hash terminal-notifier 2>/dev/null; then #osx
      terminal-notifier -message "$2" -title "$1"
    elif hash growlnotify 2>/dev/null; then #osx growl
      growlnotify -m $1 $2
    elif hash notify-send 2>/dev/null; then #ubuntu!
      notify-send $1 $2
    elif hash notifu 2>/dev/null; then #cygwyn support!
      notifu /m "$2" /p "$1"
    fi
  }
  
  
  ## Zsh hooks ##
  
  bgnotify_begin() {
    bgnotify_timestamp=$EPOCHSECONDS
    bgnotify_lastcmd=$1
    bgnotify_windowid=$(currentWindowId)
  }
  
  bgnotify_end() {
    didexit=$?
    elapsed=$(( EPOCHSECONDS - bgnotify_timestamp ))
    past_threshold=$(( elapsed >= bgnotify_threshold ))
    if (( bgnotify_timestamp > 0 )) && (( past_threshold )); then
      if [ $(currentWindowId) != "$bgnotify_windowid" ]; then
        print -n "\a"
        bgnotify_formatted "$didexit" "$bgnotify_lastcmd" "$elapsed"
      fi
    fi
    bgnotify_timestamp=0 #reset it to 0!
  }
  
  add-zsh-hook preexec bgnotify_begin
  add-zsh-hook precmd bgnotify_end