dns/show: refactor Record formatting

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/dns/show.go

@@ -1,29 +1,53 @@
 package dns
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io"
+	"os"
 	"time"
 
 	"darvaza.org/core"
+	"github.com/libdns/libdns"
 )
 
 // Show shows current DNS entries
 func (mgr *Manager) Show(ctx context.Context, names ...string) error {
+	var buf bytes.Buffer
+
 	recs, err := mgr.GetRecords(ctx, names...)
 	if err != nil {
 		return core.Wrap(err, "GetRecords")
 	}
 
 	for _, rr := range recs {
-		_, _ = fmt.Printf("%s\t%v\tIN\t%s\t%s\t; %s\n",
+		_ = fmtRecord(&buf, rr)
+		_, _ = buf.WriteRune('\n')
+	}
+	_, _ = fmt.Fprintf(&buf, "; %v records\n", len(recs))
+
+	_, err = buf.WriteTo(os.Stdout)
+	return err
+}
+
+func fmtRecord(w io.Writer, rr libdns.Record) error {
+	ttl := int(rr.TTL / time.Second)
+	if ttl < 1 {
+		ttl = 1
+	}
+
+	_, err := fmt.Fprintf(w, "%s\t%v\tIN\t%s\t%s",
 		rr.Name,
-			int(rr.TTL/time.Second),
+		ttl,
 		rr.Type,
-			rr.Value,
-			rr.ID)
+		rr.Value)
+
+	if err == nil {
+		if rr.ID != "" {
+			_, err = fmt.Fprintf(w, "\t; %s", rr.ID)
+		}
 	}
 
-	_, _ = fmt.Printf("; %v records\n", len(recs))
-	return nil
+	return err
 }