<?php
namespace Jahnke\DiscourseSso\Controller;

/***************************************************************
 *  Copyright notice
 *
 *  (c) 2016 Dirk Jahnke <dirk.jahnke@mailbox.org>
 *
 *  All rights reserved
 *
 *  This script is part of the TYPO3 project. The TYPO3 project is
 *  free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  The GNU General Public License can be found at
 *  http://www.gnu.org/copyleft/gpl.html.
 *
 *  This script is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  This copyright notice MUST APPEAR in all copies of the script!
 ***************************************************************/

use TYPO3\CMS\Core\Utility\GeneralUtility;
use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;
use \TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility;

/**
 * Controller for the Member object
 */
class SsoController extends ActionController
{


    /**
     * Compare if signed data matches given signature.
     *
     * @param string $data Signed data to be compared with.
     * @param string $sig  Signature to be compared with.
     *
     * @return boolean
     */
    private function _hashsAreEqual($data, $sig)
    {
        if ($data === null || $sig === null || is_string($data) === false || is_string($sig) === false) {
            return false;
        }

        if (strlen($data) !== strlen($sig)) {
            return false;
        }

        if (strcmp($data, $sig) === 0) {
            return true;
        }

        return false;

    }//end _hashsAreEqual()


    /**
     * Authenticate action.
     *
     * @return string
     */
    public function authenticateAction()
    {
        /** @var \TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility $configurationUtility */
        $configurationUtility = $this->objectManager->get(\TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility::class);
        $extensionConfiguration = $configurationUtility->getCurrentConfiguration('tx_dj_discourse_sso');

        // Check mandatory settings.
        if (isset($extensionConfiguration['redirect_url']) === false) {
            $errorText = '<div><b>ERROR!</b> '
                .'You should not see this message!<br />'
                .'Could not find typoscript setting plugins.tx_dj_discourse_sso.redirect_url! '
                .'Please configure the plugin.';
            return $errorText;
        } else {
            $redirectUrlRoot = $extensionConfiguration['redirect_url'];
        }

        if (isset($extensionConfiguration['shared_key']) === false) {
            $errorText = '<div><b>ERROR!</b> '
                .'You should not see this message!<br />'
                .'Could not find typoscript setting plugins.tx_dj_discourse_sso.shared_key! '
                .'Please configure the plugin.';
            return $errorText;
        } else {
            $sharedKey = $extensionConfiguration['shared_key'];
        }

        // Set some defaults.
        if (isset($extensionConfiguration['redirect_status']) === true) {
            $redirectStatus = $extensionConfiguration['redirect_status'];
        }

        if ($redirectStatus === false || ($redirectStatus < 300 || $redirectStatus > 308)) {
            // Set default.
            $redirectStatus = 303;
        }

        $hmac = hash_hmac('sha256', $sso, $this->settings['discourse_sso_shared_key']);
        if ($this->_hashsAreEqual($hmac, $sig) === false) {
            header('HTTP/1.1 403 Forbidden');
            $this->throwStatus(403, 'Bad SSO request');
        } else {
            // Valid $sso string available, convert it.
            parse_str(base64_decode($sso), $receivedPayload);
            $user = null;
            if (isset($GLOBALS['TSFE']) === true
                && isset($GLOBALS['TSFE']->fe_user) === true
                && isset($GLOBALS['TSFE']->fe_user->user) === true
            ) {
                $user = $GLOBALS['TSFE']->fe_user->user;
            }

            if (isset($user) === true) {
                $sso         = urldecode(GeneralUtility::_GP('sso'));
                $sig         = GeneralUtility::_GP('sig');
                $userId      = $user['uid'];
                $userEmail   = $user['email'];
                $userName    = $user['username'];
                $name        = $user['name'];
                $nonce       = $receivedPayload['nonce'];
                $parameters  = array(
                                'nonce'       => $nonce,
                                'external_id' => $userId,
                                'email'       => $userEmail,
                                'username'    => $userName,
                                'name'        => $name,
                               );
                $payload     = base64_encode(http_build_query($parameters));
                $signature   = hash_hmac('sha256', $payload, $this->settings['discourse_sso_shared_key']);
                $query       = http_build_query(array('sso' => $payload, 'sig' => $signature));
                $redirectUrl = $redirectUrlRoot.'/session/sso_login?'.$query;
                $this->redirectToUri($redirectUrl, 0, $redirectStatus);
            } else {
                // No user logged in.
                // Wrong setup! This plugin should be enabled only, if a user login exists.
                $errorText = '<div><b>ERROR!</b> '
                    .'You should not see this message!<br />'
                    .'This plugin should be made available only, if a Frontend User is logged in.<br />'
                    .'Please change this in the setup of this content element.';
                return $errorText;
            }//end if
        }//end if

    }//end authenticateAction()


}