Add setting to enable facial recognition for all users by default.

The default philosophy is that users must enable facial recognition
with their personal data, but in certain scenarios you may prefer to
enable it by default, for example to the family.

lib/Service/SettingsService.php

@@ -45,6 +45,10 @@ class SettingsService {
 	const CURRENT_MODEL_KEY = 'model';
 	const FALLBACK_CURRENT_MODEL = -1;
 
+	/* Enabling facial recognition for users */
+	const DEFAULT_USER_ENABLED_KEY = 'default_enabled';
+	const DEFAULT_USER_ENABLED = 'false';
+
 	/* Assigned memory for image processing */
 	const ASSIGNED_MEMORY_KEY = 'assigned_memory';
 	const MINIMUM_ASSIGNED_MEMORY = (1 * 1024 * 1024 * 1024) * 2.0 / 3.0;
@@ -83,7 +87,7 @@ class SettingsService {
 
 	/** User setting what indicates if has the analysis enabled */
 	const USER_ENABLED_KEY = 'enabled';
-	const DEFAULT_USER_ENABLED = 'false';
+	// The default is defined by system 'default_enabled' key
 
 	/** User setting that remember last images checked */
 	const STALE_IMAGES_LAST_CHECKED_KEY = 'stale_images_last_checked';
@@ -170,7 +174,8 @@ public function __construct(IConfig $config,
 	 * @param null|string $userId
 	 */
 	public function getUserEnabled (?string $userId = null): bool {
-		$enabled = $this->config->getUserValue($userId ?? $this->userId, Application::APP_NAME, self::USER_ENABLED_KEY, self::DEFAULT_USER_ENABLED);
+		$enabled = $this->config->getUserValue($userId ?? $this->userId, Application::APP_NAME, self::USER_ENABLED_KEY,
+		                                       $this->getDefaultUserEnabled());
 		return ($enabled === 'true');
 	}
 
@@ -302,6 +307,11 @@ public function setMinimumFacesInCluster($no_faces): void {
 	 * The next settings are advanced preferences that are not available in gui.
 	 * See: https://github.com/matiasdelellis/facerecognition/wiki/Settings#hidden-settings
 	 */
+	public function getDefaultUserEnabled (): bool {
+		$enabled = $this->config->getAppValue(Application::APP_NAME, self::USER_DEFAULT_ENABLED_KEY, self::DEFAULT_USER_ENABLED);
+		return ($enabled === 'true');
+	}
+
 	public function getHandleSharedFiles(): bool {
 		$handle = $this->config->getAppValue(Application::APP_NAME, self::HANDLE_SHARED_FILES_KEY, self::DEFAULT_HANDLE_SHARED_FILES);
 		return ($handle === 'true');