Mercedes: refactor token refresh (#18412)

vehicle/mercedes/identity.go

@@ -7,7 +7,6 @@ import (
 	"net/url"
 	"strings"
 	"sync"
-	"time"
 
 	"github.com/evcc-io/evcc/server/db/settings"
 	"github.com/evcc-io/evcc/util"
@@ -60,27 +59,25 @@ func NewIdentity(log *util.Logger, token *oauth2.Token, account string, region s
 
 	// reuse identity instance
 	if instance := getInstance(account); instance != nil {
-		v.log.DEBUG.Println("identity.NewIdentity - token found in instance store")
 		return instance, nil
 	}
 
+	// config token
 	if !token.Valid() {
-		token.Expiry = time.Now().Add(time.Duration(10) * time.Second)
+		token, _ = v.RefreshToken(token)
 	}
 
 	// database token
 	if !token.Valid() {
-		var tok oauth2.Token
-		if err := settings.Json(v.settingsKey(), &tok); err == nil {
-			v.log.DEBUG.Println("identity.NewIdentity - database token found")
-			token = &tok
+		if err := settings.Json(v.settingsKey(), &token); err != nil {
+			return nil, errors.New("missing token")
 		}
-	}
 
-	if !token.Valid() && token.RefreshToken != "" {
-		v.log.DEBUG.Println("identity.NewIdentity - refreshToken started")
-		if tok, err := v.RefreshToken(token); err == nil {
-			token = tok
+		if !token.Valid() {
+			var err error
+			if token, err = v.RefreshToken(token); err != nil {
+				return nil, err
+			}
 		}
 	}
 
@@ -104,6 +101,10 @@ func (v *Identity) RefreshToken(token *oauth2.Token) (*oauth2.Token, error) {
 	v.mu.Lock()
 	defer v.mu.Unlock()
 
+	if token == nil {
+		return nil, errors.New("token is nil")
+	}
+
 	data := url.Values{
 		"grant_type":    {"refresh_token"},
 		"refresh_token": {token.RefreshToken},