iRule Newbie learning - need validation

when HTTP_REQUEST {

   switch -glob [string tolower [HTTP::host]] {
      "www.*" {
          Host started with "www.".  Allow request without redirecting it?
      }
      "*[a-z]*" {
          Host is not null and not an IP address
         HTTP::redirect https://[getfield [HTTP::host] ":" 1][HTTP::uri]
      }
      default {
          Host is null or an IP address
         HTTP::redirect "https://default.example.com[HTTP::uri]"
      }
   }
}