Add comment for shortenHostname function

Signed-off-by: Rizwana777 <rizwananaaz177@gmail.com>

controllers/argocd/route.go

@@ -31,6 +31,12 @@ import (
 
 var routeAPIFound = false
 
+const (
+	maxLabelLength     = 63
+	maxHostnameLength  = 253
+	minFirstLabelSize1 = 20
+)
+
 // IsRouteAPIAvailable returns true if the Route API is present.
 func IsRouteAPIAvailable() bool {
 	return routeAPIFound
@@ -382,6 +388,12 @@ func (r *ReconcileArgoCD) reconcileApplicationSetControllerWebhookRoute(cr *argo
 	return r.Client.Update(context.TODO(), route)
 }
 
+// The algorithm used by this function is:
+// - If the FIRST label ("console-openshift-console" in the above case) is longer than 63 characters, shorten (truncate the end) it to 63.
+// - If any other label is longer than 63 characters, return an error
+// - After all the labels are 63 characters or less, check the length of the overall hostname:
+//   - If the overall hostname is > 255, then shorten the FIRST label until the host name is < 255
+//   - After the FIRST label has been shortened, if it is < 20, then return an error (this is a sanity test to ensure the label is likely to be unique)
 func shortenHostname(hostname string) (string, error) {
 	if hostname == "" {
 		return "", nil
@@ -391,13 +403,13 @@ func shortenHostname(hostname string) (string, error) {
 	labels := strings.Split(hostname, ".")
 
 	// Check and truncate the FIRST label if longer than 63 characters
-	if len(labels[0]) > 63 {
-		labels[0] = labels[0][:63]
+	if len(labels[0]) > maxLabelLength {
+		labels[0] = labels[0][:maxLabelLength]
 	}
 
 	// Check other labels and return an error if any is longer than 63 characters
 	for _, label := range labels[1:] {
-		if len(label) > 63 {
+		if len(label) > maxLabelLength {
 			return "", fmt.Errorf("label length exceeds 63 characters")
 		}
 	}
@@ -406,15 +418,15 @@ func shortenHostname(hostname string) (string, error) {
 	resultHostname := strings.Join(labels, ".")
 
 	// Check and shorten the overall hostname
-	if len(resultHostname) > 253 {
-		// Shorten the first label until the length is less than 255
-		for len(resultHostname) > 253 && len(labels[0]) > 20 {
+	if len(resultHostname) > maxHostnameLength {
+		// Shorten the first label until the length is less than 253
+		for len(resultHostname) > maxHostnameLength && len(labels[0]) > 20 {
 			labels[0] = labels[0][:len(labels[0])-1]
 			resultHostname = strings.Join(labels, ".")
 		}
 
 		// Check if the first label is still less than 20 characters
-		if len(labels[0]) < 20 {
+		if len(labels[0]) < minFirstLabelSize1 {
 			return "", fmt.Errorf("shortened first label is less than 20 characters")
 		}
 	}