WebAuthn passwordless authentication

Method to get additional login buttons

libraries/src/Helper/AuthenticationHelper.php

@@ -57,4 +57,91 @@ public static function getTwoFactorMethods()
 
 		return $options;
 	}
+
+	/**
+	 * Get additional login buttons to add in a login module. These buttons can be used for authentication methods
+	 * external to Joomla such as WebAuthn, login with social media providers, login with third party providers or even
+	 * login with third party Single Sign On (SSO) services.
+	 *
+	 * Button definitions are returned by the onUserLoginButtons event handlers in plugins. By default, only system and
+	 * user plugins are taken into account. The former because they are always loaded. The latter are explicitly loaded
+	 * in this method.
+	 *
+	 * The onUserLoginButtons event handlers must conform to the following method definition:
+	 *
+	 * public function onUserLoginButtons(string $moduleId, string $usernameFieldId): array
+	 *
+	 * The onUserLoginButtons event handlers must return a simple array containing 0 or more button definitions.
+	 *
+	 * Each button definition is a hash array with the following keys:
+	 *
+	 * - label      The label of the button
+	 * - onclick    The onclick attribute, used to fire a JavaScript event
+	 * - icon       [optional] A CSS class or an image path for an optional icon displayed before the label
+	 * - class      [optional] CSS class(es) to be added to the button
+	 * - id         [optional] The ID of the button.
+	 *
+	 * @param   string  $moduleId         The HTML ID of the module container.
+	 * @param   string  $usernameFieldId  The HTML ID of the login module's username field.
+	 *
+	 * @return  array  Button definitions.
+	 *
+	 * @since 4.0.0
+	 */
+	public static function getLoginButtons(string $moduleId, string $usernameFieldId): array
+	{
+		// Get all the User plugins.
+		PluginHelper::importPlugin('user');
+
+		// Trigger the onUserLoginButtons event and return the button definitions.
+		$results = Factory::getApplication()->triggerEvent('onUserLoginButtons', [$moduleId, $usernameFieldId]);
+		$buttons = [];
+
+		foreach ($results as $result)
+		{
+			// Did we get garbage back from the plugin?
+			if (!is_array($result) || empty($result))
+			{
+				continue;
+			}
+
+			// Did the developer accidentally return a single button definition instead of an array?
+			if (array_key_exists('label', $result))
+			{
+				$result = [$result];
+			}
+
+			// Process each button, making sure it conforms to the required definition
+			foreach ($result as $item)
+			{
+				// Force mandatory fields
+				$button = array_merge([
+					'label'   => '',
+					'icon'    => '',
+					'class'   => '',
+					'id'      => '',
+					'onclick' => '',
+				], $item);
+
+				// Unset anything that doesn't conform to a button definition
+				foreach (array_keys($button) as $key)
+				{
+					if (!in_array($key, ['label', 'icon', 'class', 'id', 'onclick']))
+					{
+						unset($button[$key]);
+					}
+				}
+
+				// We need a label and an onclick handler at the bare minimum
+				if (empty($button['label']) || empty($button['onclick']))
+				{
+					continue;
+				}
+
+				$buttons[] = $button;
+			}
+		}
+
+		return $buttons;
+	}
 }