zones: reduce writeEnvZone() complexity

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

pkg/zones/env.go

@@ -31,25 +31,7 @@ func (m *Zones) writeEnvZone(w io.Writer, z *Zone) {
 	m.writeEnvVar(w, z.Name, "ZONE%v_%s", zoneID, "NAME")
 
 	// ZONE{zoneID}_GW
-	firstNodeID := 0
-	gatewayID := 0
-	z.ForEachMachine(func(p *Machine) bool {
-		nodeID := p.ID()
-
-		if firstNodeID == 0 {
-			firstNodeID = nodeID
-		}
-
-		if _, found := p.getRingInfo(0); found {
-			gatewayID = nodeID
-		}
-
-		return gatewayID != 0
-	})
-
-	if gatewayID == 0 {
-		gatewayID = firstNodeID
-	}
+	gatewayID := getRingZeroGatewayID(z)
 	m.writeEnvVar(w, fmt.Sprintf("%v", gatewayID), "ZONE%v_%s", zoneID, "GW")
 
 	// ZONE{zoneID}_IP
@@ -95,3 +77,28 @@ func genEnvZoneNodes(z *Zone) string {
 	}
 	return strings.Join(s, " ")
 }
+
+func getRingZeroGatewayID(z *Zone) int {
+	var firstNodeID, gatewayID int
+
+	z.ForEachMachine(func(p *Machine) bool {
+		nodeID := p.ID()
+
+		if firstNodeID == 0 {
+			firstNodeID = nodeID
+		}
+
+		if _, found := p.getRingInfo(0); found {
+			gatewayID = nodeID
+		}
+
+		return gatewayID != 0
+	})
+
+	switch {
+	case gatewayID == 0:
+		return firstNodeID
+	default:
+		return gatewayID
+	}
+}