Abffilter Role Manager replacement

/*-------------------------------------------------------------------------
		Role Manager: (replace in members/extension.driver.php when using Abffilter)
	-------------------------------------------------------------------------*/

		public function checkFrontendPagePermissions($context) {
			$isLoggedIn = false;
			$errors = array();

			// Checks $_REQUEST to see if a Member Action has been requested,
			// member-action['login'] and member-action['logout']/?member-action=logout
			// are the only two supported at this stage.
			if(is_array($_REQUEST['member-action'])){
				list($action) = array_keys($_REQUEST['member-action']);
			} else {
				$action = $_REQUEST['member-action'];
			}

			// Check to see a Member is already logged in.
			$isLoggedIn = $this->getMemberDriver()->isLoggedIn($errors);

			// Logout
			if(trim($action) == 'logout') {
				/**
				 * Fired just before a member is logged out (and page redirection),
				 * this delegate provides the current Member ID
				 *
				 * @delegate MembersPreLogout
				 * @param string $context
				 *  '/frontend/'
				 * @param integer $member_id
				 *  The Member ID of the member who is about to logged out
				 */
				Symphony::ExtensionManager()->notifyMembers('MembersPreLogout', '/frontend/', array(
					'member_id' => $this->getMemberDriver()->getMemberID()
				));

				$this->getMemberDriver()->logout();

				// If a redirect is provided, redirect to that, otherwise return the user
				// to the index of the site. Issue #51 & #121
				if(isset($_REQUEST['redirect'])) redirect($_REQUEST['redirect']);

				redirect(URL);
			}

			// Login
			else if(trim($action) == 'login' && !is_null($_POST['fields'])) {
				// If a Member is already logged in and another Login attempt is requested
				// log the Member out first before trying to login with new details.
				if($isLoggedIn) {
					$this->getMemberDriver()->logout();
				}
				if($this->getMemberDriver()->login($_POST['fields'])) {
					/**
					 * Fired just after a Member has successfully logged in, this delegate
					 * provides the current Member ID. This delegate is fired just before
					 * the page redirection (if it is provided)
					 *
					 * @delegate MembersPostLogin
					 * @param string $context
					 *  '/frontend/'
					 * @param integer $member_id
					 *  The Member ID of the member who just logged in.
					 * @param Entry $member
					 *  The Entry object of the logged in Member.
					 */
					Symphony::ExtensionManager()->notifyMembers('MembersPostLogin', '/frontend/', array(
						'member_id' => $this->getMemberDriver()->getMemberID(),
						'member' => $this->getMemberDriver()->getMember()
					));
					Symphony::ExtensionManager()->notifyMembers('MembersLoginSuccess', '/frontend/', array(
						'member_id' => $this->getMemberDriver()->getMemberID(),
						'member' => $this->getMemberDriver()->getMember()
					));

					if(isset($_POST['redirect'])) redirect($_POST['redirect']);
				}
				else {
					self::$_failed_login_attempt = true;
					Symphony::ExtensionManager()->notifyMembers('MembersLoginFailure', '/frontend/', array(
						'member_id' => $this->getMemberDriver()->getMemberID(),
						'member' => $this->getMemberDriver()->getMember()
					));
				}
			}

			$this->Member->initialiseMemberObject();

			if($isLoggedIn && $this->getMemberDriver()->getMember() instanceOf Entry) {
				$this->updateSystemTimezoneOffset($this->getMemberDriver()->getMemberID());

				if(!is_null(extension_Members::getFieldHandle('role'))) {
					$role_data = $this->getMemberDriver()->getMember()->getData(extension_Members::getField('role')->get('id'));
				}
			}

			// If there is no role field, or a Developer is logged in, return, as Developers
			// should be able to access every page.
			if(
				is_null(extension_Members::getFieldHandle('role'))
				|| (Frontend::instance()->Author instanceof Author && Frontend::instance()->Author->isDeveloper())
			) return;

			$role_id = ($isLoggedIn) ? $role_data['role_id'] : Role::PUBLIC_ROLE;
			$role = RoleManager::fetch($role_id);

			if($role instanceof Role && !$role->canAccessPage((int)$context['page_data']['id'])) {
				// User has no access to this page, so look for a custom 403 page
				if($row = PageManager::fetchPageByType('403')) {
					$row['type'] = PageManager::fetchPageTypes($row['id']);
					$row['filelocation'] = PageManager::resolvePageFileLocation($row['path'], $row['handle']);

					$context['page_data'] = $row;
					return;
				}
				else {
					// No custom 403, just throw default 403
					GenericExceptionHandler::$enabled = true;
					throw new SymphonyErrorPage(
						__('The page you have requested has restricted access permissions.'),
						__('Forbidden'),
						'error',
						array('header' => 'HTTP/1.0 403 Forbidden')
					);
				}
			}
		}