Do not export func MakeSendEndpoint.

fcm.go

@@ -27,6 +27,7 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
 )
 
 const tracerName = "git.bit5.ru/backend/fcm"
@@ -46,7 +47,7 @@ var (
 	AuthScopes = []string{"https://www.googleapis.com/auth/firebase.messaging"}
 )
 
-func MakeSendEndpoint(projectId string) string {
+func makeSendEndpoint(projectId string) string {
 	return fmt.Sprintf("https://fcm.googleapis.com/v1/projects/%s/messages:send", projectId)
 }
 
@@ -78,23 +79,19 @@ func ReadCredentialsFromFile(filename string) (Credentials, error) {
 	return c, nil
 }
 
-type ClientConfig struct {
-	SendEndpoint string
-}
-
 type Client struct {
-	cfg    ClientConfig
-	ts     oauth2.TokenSource
-	hc     *http.Client
-	logger logr.Logger
+	sendEndpoint string
+	ts           oauth2.TokenSource
+	hc           *http.Client
+	logger       logr.Logger
 }
 
-func NewClient(cfg ClientConfig, ts oauth2.TokenSource, hc *http.Client, logger logr.Logger) *Client {
+func NewClient(projectId string, ts oauth2.TokenSource, hc *http.Client, logger logr.Logger) *Client {
 	return &Client{
-		cfg:    cfg,
-		ts:     ts,
-		hc:     hc,
-		logger: logger,
+		sendEndpoint: makeSendEndpoint(projectId),
+		ts:           ts,
+		hc:           hc,
+		logger:       logger,
 	}
 }
 
@@ -166,7 +163,11 @@ func (c *Client) Validate(ctx context.Context, message Message) (string, error)
 
 func (c *Client) doSendRequest(ctx context.Context, req SendRequest, loggerEnabled bool) (SendResponse, error) {
 
-	_, span := tracer.Start(ctx, "Client.doSendRequest")
+	spanAttrs := trace.WithAttributes(
+		attribute.String("token", req.Message.Token),
+	)
+
+	_, span := tracer.Start(ctx, "Client.doSendRequest", spanAttrs)
 	defer span.End()
 
 	accessToken, err := c.ts.Token()
@@ -189,7 +190,7 @@ func (c *Client) doSendRequest(ctx context.Context, req SendRequest, loggerEnabl
 		c.logger.Info("sending", "message", data)
 	}
 
-	request, err := http.NewRequest(http.MethodPost, c.cfg.SendEndpoint, bytes.NewReader(data))
+	request, err := http.NewRequest(http.MethodPost, c.sendEndpoint, bytes.NewReader(data))
 	if err != nil {
 		span.SetStatus(codes.Error, err.Error())
 		span.RecordError(err)

message.go

@@ -1,5 +1,7 @@
 package fcm
 
+// Message to send by Firebase Cloud Messaging Service.
+// https://firebase.google.com/docs/reference/fcm/rest/v1/projects.messages#resource:-message
 type Message struct {
 	// Union field target can be only one of the following:
 	Token     string `json:"token,omitempty"`
@@ -16,6 +18,7 @@ type Message struct {
 }
 
 // Basic notification template to use across all platforms.
+// https://firebase.google.com/docs/reference/fcm/rest/v1/projects.messages#notification
 type Notification struct {
 	Title string `json:"title,omitempty"`
 	Body  string `json:"body,omitempty"`
@@ -173,8 +176,8 @@ type ApnsPayload struct {
 	Aps ApnsPayloadKeys `json:"aps"`
 
 	// TODO: add support for custom keys
-	// https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/generating_a_remote_notification
-	customKeys map[string]interface{}
+	// https://developer.apple.com/documentation/usernotifications/generating-a-remote-notification
+	customKeys map[string]any
 }
 
 type ApnsPayloadKeys struct {