def to_pretty(t)
  a = (Time.now - t).to_i

  case a
  when 0               then "just now"
  when 1               then "a second ago"
  when 2..59           then a.to_s + " seconds ago"
  when 60..119         then "a minute ago" # 120 = 2 minutes
  when 120..3540       then (a/60).to_i.to_s + " minutes ago"
  when 3541..7100      then "an hour ago" # 3600 = 1 hour
  when 7101..82800     then ((a + 99)/3600).to_i.to_s + " hours ago"
  when 82801..172000   then "a day ago" # 86400 = 1 day
  when 172001..518400  then ((a + 800)/(60*60*24)).to_i.to_s + " days ago"
  when 518400..1036800 then "a week ago"
  else                      ((a + 180000)/(60*60*24*7)).to_i.to_s + " weeks ago"
  end
end