fix: handle type string for oauth groups

internal/constants/constants.go

@@ -2,10 +2,10 @@ package constants
 
 // Claims are the OIDC supported claims (prefered username is included for convinience)
 type Claims struct {
-	Name              string   `json:"name"`
+	Name              string `json:"name"`
-	Email             string   `json:"email"`
+	Email             string `json:"email"`
-	PreferredUsername string   `json:"preferred_username"`
+	PreferredUsername string `json:"preferred_username"`
-	Groups            []string `json:"groups"`
+	Groups            any    `json:"groups"`
 }
 
 // Version information

internal/handlers/oauth.go

@@ -189,7 +189,7 @@ func (h *Handlers) OAuthCallbackHandler(c *gin.Context) {
 		Name:        name,
 		Email:       user.Email,
 		Provider:    providerName.Provider,
-		OAuthGroups: strings.Join(user.Groups, ","),
+		OAuthGroups: utils.CoalesceToString(user.Groups),
 	})
 
 	// Check if we have a redirect URI

internal/utils/utils.go

@@ -327,3 +327,15 @@ func DeriveKey(secret string, info string) (string, error) {
 	encodedKey := base64.StdEncoding.EncodeToString(key)
 	return encodedKey, nil
 }
+
+func CoalesceToString(value any) string {
+	switch v := value.(type) {
+	case []string:
+		return strings.Join(v, ",")
+	case string:
+		return v
+	default:
+		log.Warn().Interface("value", value).Msg("Unsupported type, returning empty string")
+		return ""
+	}
+}

internal/utils/utils_test.go

@@ -511,3 +511,38 @@ func TestDeriveKey(t *testing.T) {
 		t.Fatalf("Expected %v, got %v", expected, result)
 	}
 }
+
+func TestCoalesceToString(t *testing.T) {
+	t.Log("Testing coalesce to string with a string")
+
+	value := "test"
+	expected := "test"
+
+	result := utils.CoalesceToString(value)
+
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+
+	t.Log("Testing coalesce to string with a slice of strings")
+
+	valueSlice := []string{"test1", "test2"}
+	expected = "test1,test2"
+
+	result = utils.CoalesceToString(valueSlice)
+
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+
+	t.Log("Testing coalesce to string with an unsupported type")
+
+	valueUnsupported := 12345
+	expected = ""
+
+	result = utils.CoalesceToString(valueUnsupported)
+
+	if result != expected {
+		t.Fatalf("Expected %v, got %v", expected, result)
+	}
+}