Some code improvements

* Remove shadowing of predeclared identifier: new.
* strings.ReplaceAll instead of strings.Replace with -1.
* Change strings.ToLower comparison to strings.EqualFold.
* Rewrite if-else-if-else chain as a switch.

providers/google.go

@@ -195,9 +195,10 @@ func userInGroup(service *admin.Service, groups []string, email string) bool {
 		r, err := req.Do()
 		if err != nil {
 			err, ok := err.(*googleapi.Error)
-			if ok && err.Code == 404 {
+			switch {
+			case ok && err.Code == 404:
 				logger.Printf("error checking membership in group %s: group does not exist", group)
-			} else if ok && err.Code == 400 {
+			case ok && err.Code == 400:
 				// It is possible for Members.HasMember to return false even if the email is a group member.
 				// One case that can cause this is if the user email is from a different domain than the group,
 				// e.g. "member@otherdomain.com" in the group "group@mydomain.com" will result in a 400 error
@@ -215,7 +216,7 @@ func userInGroup(service *admin.Service, groups []string, email string) bool {
 				if r.Status == "ACTIVE" {
 					return true
 				}
-			} else {
+			default:
 				logger.Printf("error checking group membership: %v", err)
 			}
 			continue