LG ESS: cleanup code and require paramters on all instantiations

meter/lgpcs/lgpcs.go

@@ -47,58 +47,57 @@ type Com struct {
 	cachedData func() (interface{}, error)
 }
 
-var once sync.Once
-var instance *Com
+var (
+	once     sync.Once
+	mu       sync.Mutex
+	instance *Com
+)
 
 // GetInstance implements the singleton pattern to handle the access via the authkey to the PCS of the LG ESS HOME system
 func GetInstance(uri, password string, cache time.Duration) (*Com, error) {
-	const emptyUri = "https:"
 	uri = util.DefaultScheme(strings.TrimSuffix(uri, "/"), "https")
 
+	var err error
 	once.Do(func() {
 		log := util.NewLogger("lgess")
-		instance = &Com{
+		inst := &Com{
 			Helper:   request.NewHelper(log),
 			uri:      uri,
 			password: password,
 		}
 
 		// ignore the self signed certificate
-		instance.Client.Transport = request.NewTripper(log, transport.Insecure())
+		inst.Client.Transport = request.NewTripper(log, transport.Insecure())
 
 		// caches the data access for the "cache" time duration
 		// sends a new request to the pcs if the cache is expired and Data() requested
-		instance.cachedData = provider.NewCached(func() (interface{}, error) {
-			return instance.refreshData()
+		inst.cachedData = provider.NewCached(func() (interface{}, error) {
+			return inst.refreshData()
 		}, cache).InterfaceGetter()
+
+		// do first login if no authKey exists and uri and password exist
+		if inst.authKey == "" && inst.uri != "" && inst.password != "" {
+			err = instance.Login()
+		}
+
+		mu.Lock()
+		instance = inst
+		mu.Unlock()
 	})
 
-	// it is sufficient to provide the uri once ... if not provided yet set uri now
-	if instance.uri == emptyUri {
-		instance.uri = uri
-	}
+	mu.Lock()
+	defer mu.Unlock()
 
 	// check if different uris are provided
-	if uri != emptyUri && instance.uri != uri {
+	if uri != "" && instance.uri != uri {
 		return nil, fmt.Errorf("uri mismatch: %s vs %s", instance.uri, uri)
 	}
 
-	// it is sufficient to provide the password once ... if not provided yet set password now
-	if instance.password == "" {
-		instance.password = password
-	}
-
 	// check if different passwords are provided
 	if password != "" && instance.password != password {
 		return nil, errors.New("password mismatch")
 	}
 
-	// do first login if no authKey exists and uri and password exist
-	var err error
-	if instance.authKey == "" && instance.uri != emptyUri && instance.password != "" {
-		err = instance.Login()
-	}
-
 	return instance, err
 }
 

util/net.go

@@ -28,6 +28,9 @@ func DefaultScheme(uri string, scheme string) string {
 	}
 
 	switch {
+	case u.String() == "":
+		return ""
+
 	case u.Scheme == "":
 		// scheme missing
 		u.Scheme = scheme

util/net_test.go

@@ -38,3 +38,10 @@ func TestDefaultScheme(t *testing.T) {
 		t.Errorf("expected %s, got %s", expect, uri)
 	}
 }
+func TestDefaultSchemeWithEmptyUri(t *testing.T) {
+	expect := ""
+
+	if uri := DefaultScheme("", "http"); uri != expect {
+		t.Errorf("expected %s, got %s", expect, uri)
+	}
+}