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libraries/fof30/Utils/DynamicGroups.php

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+<?php
+/**
+ * @package   FOF
+ * @copyright Copyright (c)2010-2021 Nicholas K. Dionysopoulos / Akeeba Ltd
+ * @license   GNU General Public License version 2, or later
+ */
+
+namespace FOF30\Utils;
+
+defined('_JEXEC') || die;
+
+use FOF30\Container\Container;
+use ReflectionClass;
+use ReflectionException;
+use ReflectionObject;
+
+/**
+ * Dynamic user to user group assignment.
+ *
+ * This class allows you to add / remove the currently logged in user to a user group without writing the information to
+ * the database. This is useful when you want to allow core and third party code to allow or prohibit display of
+ * information and / or taking actions based on a condition controlled in your code.
+ */
+class DynamicGroups
+{
+	/**
+	 * Add the current user to a user group just for this page load.
+	 *
+	 * @param   int  $groupID  The group ID to add the current user into.
+	 *
+	 * @return  void
+	 */
+	public static function addGroup($groupID)
+	{
+		self::addRemoveGroup($groupID, true);
+		self::cleanUpUserObjectCache();
+	}
+
+	/**
+	 * Remove the current user from a user group just for this page load.
+	 *
+	 * @param   int  $groupID  The group ID to remove the current user from.
+	 *
+	 * @return  void
+	 */
+	public static function removeGroup($groupID)
+	{
+		self::addRemoveGroup($groupID, false);
+		self::cleanUpUserObjectCache();
+	}
+
+	/**
+	 * Internal function to add or remove the current user from a user group just for this page load.
+	 *
+	 * @param   int   $groupID  The group ID to add / remove the current user from.
+	 * @param   bool  $add      Add (true) or remove (false) the user?
+	 *
+	 * @return  void
+	 */
+	protected static function addRemoveGroup($groupID, $add)
+	{
+		// Get a fake container (we need it for its platform interface)
+		$container = Container::getInstance('com_FOOBAR');
+
+		/**
+		 * Make sure that Joomla has retrieved the user's groups from the database.
+		 *
+		 * By going through the User object's getAuthorisedGroups we force Joomla to go through Access::getGroupsByUser
+		 * which retrieves the information from the database and caches it into the Access helper class.
+		 */
+		$container->platform->getUser()->getAuthorisedGroups();
+		$container->platform->getUser($container->platform->getUser()->id)->getAuthorisedGroups();
+
+		/**
+		 * Now we can get a Reflection object into Joomla's Access helper class and manipulate its groupsByUser cache.
+		 */
+		$className = class_exists('Joomla\\CMS\\Access\\Access') ? 'Joomla\\CMS\\Access\\Access' : 'JAccess';
+
+		try
+		{
+			$reflectedAccess = new ReflectionClass($className);
+		}
+		catch (ReflectionException $e)
+		{
+			// This should never happen!
+			$container->platform->logDebug('Cannot locate the Joomla\\CMS\\Access\\Access or JAccess class. Is your Joomla installation broken or too old / too new?');
+
+			return;
+		}
+
+		$groupsByUser = $reflectedAccess->getProperty('groupsByUser');
+		$groupsByUser->setAccessible(true);
+		$rawGroupsByUser = $groupsByUser->getValue();
+
+		/**
+		 * Next up, we need to manipulate the keys of the cache which contain user to user group assignments.
+		 *
+		 * $rawGroupsByUser (JAccess::$groupsByUser) stored the group ownership as userID:recursive e.g. 0:1 for the
+		 * default user, recursive. We need to deal with four keys: 0:1, 0:0, myID:1 and myID:0
+		 */
+		$user = $container->platform->getUser();
+		$keys = ['0:1', '0:0', $user->id . ':1', $user->id . ':0'];
+
+		foreach ($keys as $key)
+		{
+			if (!array_key_exists($key, $rawGroupsByUser))
+			{
+				continue;
+			}
+
+			$groups = $rawGroupsByUser[$key];
+
+			if ($add)
+			{
+				if (in_array($groupID, $groups))
+				{
+					continue;
+				}
+
+				$groups[] = $groupID;
+			}
+			else
+			{
+				if (!in_array($groupID, $groups))
+				{
+					continue;
+				}
+
+				$removeKey = array_search($groupID, $groups);
+				unset($groups[$removeKey]);
+			}
+
+			$rawGroupsByUser[$key] = $groups;
+		}
+
+		// We can commit our changes back to the cache property and make it publicly inaccessible again.
+		$groupsByUser->setValue(null, $rawGroupsByUser);
+		$groupsByUser->setAccessible(false);
+
+		/**
+		 * We are not done. Caching user groups is only one aspect of Joomla access management. Joomla also caches the
+		 * identities, i.e. the user group assignment per user, in a different cache. We need to reset it to for our
+		 * user.
+		 *
+		 * Do note that we CAN NOT use clearStatics since that also clears the user group assignment which we assigned
+		 * dynamically. Therefore calling it would destroy our work so far.
+		 */
+		$refProperty = $reflectedAccess->getProperty('identities');
+		$refProperty->setAccessible(true);
+		$identities = $refProperty->getValue();
+
+		$keys = [$user->id, 0];
+
+		foreach ($keys as $key)
+		{
+			if (!array_key_exists($key, $identities))
+			{
+				continue;
+			}
+
+			unset($identities[$key]);
+		}
+
+		$refProperty->setValue(null, $identities);
+		$refProperty->setAccessible(false);
+	}
+
+	/**
+	 * Clean up the current user's authenticated groups cache.
+	 *
+	 * @return  void
+	 */
+	protected static function cleanUpUserObjectCache()
+	{
+		// Get a fake container (we need it for its platform interface)
+		$container = Container::getInstance('com_FOOBAR');
+
+		$user          = $container->platform->getUser();
+		$reflectedUser = new ReflectionObject($user);
+
+		// Clear the user group cache
+		$refProperty = $reflectedUser->getProperty('_authGroups');
+		$refProperty->setAccessible(true);
+		$refProperty->setValue($user, []);
+		$refProperty->setAccessible(false);
+
+		// Clear the view access level cache
+		$refProperty = $reflectedUser->getProperty('_authLevels');
+		$refProperty->setAccessible(true);
+		$refProperty->setValue($user, []);
+		$refProperty->setAccessible(false);
+
+		// Clear the authenticated actions cache. I haven't seen it used anywhere but it's there, so...
+		$refProperty = $reflectedUser->getProperty('_authActions');
+		$refProperty->setAccessible(true);
+		$refProperty->setValue($user, []);
+		$refProperty->setAccessible(false);
+	}
+}