module Base64Bp

def urlsafe_decode64(str)
  str = str.tr("-_", "+/")
  if !str.end_with?("=") && str.length % 4 != 0
    str = str.ljust((str.length + 3) & ~3, "=")
  end
  strict_decode64(str)
end

def urlsafe_encode64(bin, padding:)
  str = strict_encode64(bin)
  str.tr!("+/", "-_")
  str.delete!("=") unless padding
  str
end