class ModuleFacebookRegistration extends Module
{

    /**
     * Template
     * @var string
     */
    protected $strTemplate = 'mod_facebookRegistration';

    /**
     * Display a wildcard in the back end
     * @return string
     */
    public function generate()
    {
        if (TL_MODE == 'BE')
        {
            $objTemplate = new BackendTemplate('be_wildcard');

            $objTemplate->wildcard = '### USER FACEBOOK REGISTRATION ###';
            $objTemplate->title = $this->headline;
            $objTemplate->id = $this->id;
            $objTemplate->link = $this->name;
            $objTemplate->href = 'contao/main.php?do=themes&table=tl_module&act=edit&id=' . $this->id;

            return $objTemplate->parse();
        }

        $this->editable = deserialize($this->editable);

        // Return if there are no editable fields
        if (!is_array($this->editable) || count($this->editable) < 1 || FE_USER_LOGGED_IN)
        {
            //return '';
        }

        return parent::generate();
    }


    /**
     * Generate module
     */
    protected function compile()
    {
        global $objPage;

        $GLOBALS['TL_LANGUAGE'] = $objPage->language;

        $this->loadLanguageFile('tl_member');
        $this->loadDataContainer('tl_member');

        // Call onload_callback (e.g. to check permissions)
        if (is_array($GLOBALS['TL_DCA']['tl_member']['config']['onload_callback']))
        {
            foreach ($GLOBALS['TL_DCA']['tl_member']['config']['onload_callback'] as $callback)
            {
                if (is_array($callback))
                {
                    $this->import($callback[0]);
                    $this->$callback[0]->$callback[1]();
                }
            }
        }

        $this->Template->fields = '';
        $this->Template->tableless = $this->tableless;
        $doNotSubmit = false;


        $arrUser = array();
        $arrFields = array();
        $hasUpload = false;
        $i = 0;

        // Create new user if there are no errors and the signed request is correct
        if ($_REQUEST['signed_request'])
        {
            $response = $this->parse_signed_request($_REQUEST['signed_request']);
            $arrUser = array(
                'firstname' => $response['registration']['first_name'],
                'lastname' => $response['registration']['last_name'],
                'dateOfBirth' =>  strtotime($response['registration']['birthday']),
                'gender' => $response['registration']['gender'],
                'street' => $response['registration']['street'],
                'postal' => $response['registration']['postal'],
                'city' => $response['registration']['city'],
                'email' => $response['registration']['email'],
                'username' => $response['registration']['username'],
                'fbUid' => $response['user_id'],
                'password' => '829c3804401b0727f70f73d4415e162400cbe57b',
                'mobile' => $response['registration']['phone']
            );

            // check if the user already exists
            $resultSettings     = $this->Database->prepare("SELECT fbUid FROM tl_member WHERE fbUid=?")
                                    ->execute($arrUser['fbUid'])->fbUid;
            if($resultSettings){
                $this->jumpToOrReload($this->jumpTo);
                exit;
            }

            // check if Email-Adress already exists and merge accounts
            $resultEmail    = $this->Database->prepare("SELECT email FROM tl_member WHERE email=?")
                                    ->execute($arrUser['email'])->email;
            if($resultEmail){
                $this->mergeAccounts($arrUser);
                $this->jumpToOrReload($this->jumpTo);
                exit;
            }

            // its a new user
            $this->createNewUser($arrUser);

        }


        $this->Template->loginDetails = $GLOBALS['TL_LANG']['tl_member']['loginDetails'];
        $this->Template->addressDetails = $GLOBALS['TL_LANG']['tl_member']['addressDetails'];
        $this->Template->contactDetails = $GLOBALS['TL_LANG']['tl_member']['contactDetails'];
        $this->Template->personalData = $GLOBALS['TL_LANG']['tl_member']['personalData'];
        $this->Template->captchaDetails = $GLOBALS['TL_LANG']['MSC']['securityQuestion'];

        // Add groups
        foreach ($arrFields as $k=>$v)
        {
            $this->Template->$k = $v;
        }

        $this->Template->captcha = $arrFields['captcha'];
        $this->Template->formId = 'tl_registration';
        $this->Template->slabel = specialchars($GLOBALS['TL_LANG']['MSC']['register']);
        $this->Template->action = $this->getIndexFreeRequest();

        // HOOK: add memberlist fields
        if (in_array('memberlist', $this->Config->getActiveModules()))
        {
            $this->Template->profile = $arrFields['profile'];
            $this->Template->profileDetails = $GLOBALS['TL_LANG']['tl_member']['profileDetails'];
        }

        // HOOK: add newsletter fields
        if (in_array('newsletter', $this->Config->getActiveModules()))
        {
            $this->Template->newsletter = $arrFields['newsletter'];
            $this->Template->newsletterDetails = $GLOBALS['TL_LANG']['tl_member']['newsletterDetails'];
        }

        // HOOK: add helpdesk fields
        if (in_array('helpdesk', $this->Config->getActiveModules()))
        {
            $this->Template->helpdesk = $arrFields['helpdesk'];
            $this->Template->helpdeskDetails = $GLOBALS['TL_LANG']['tl_member']['helpdeskDetails'];
        }
    }

    /**
     * function merges a user if the email-adress already exists
     *
     */
    public function mergeAccounts($arrUser){
        $this->Database->prepare("UPDATE tl_member SET firstname=? , lastname=?, dateOfBirth=?, gender=?, street=?,
                                    postal=?, city=?, email=?, username=?, fbUid=?, password=?, mobile=? WHERE email=?")
                        ->execute(
                        $arrUser['firstname'],
                        $arrUser['lastname'],
                        $arrUser['dateOfBirth'],
                        $arrUser['gender'],
                        $arrUser['street'],
                        $arrUser['postal'],
                        $arrUser['city'],
                        $arrUser['email'],
                        $arrUser['username'],
                        $arrUser['fbUid'],
                        $arrUser['password'],
                        $arrUser['mobile'],
                        $arrUser['email']
                        );
    }

    /**
     * Create a new user and redirect
     * @param array
     */
    protected function createNewUser($arrData)
    {
        $arrData['tstamp'] = time();
        $arrData['login'] = $this->reg_allowLogin;
        $arrData['activation'] = md5(uniqid(mt_rand(), true));
        $arrData['dateAdded'] = $arrData['tstamp'];

        // Set default groups
        if (!array_key_exists('groups', $arrData))
        {
            $arrData['groups'] = $this->reg_groups;
        }

        // Make sure newsletter is an array
        if (isset($arrData['newsletter']) && !is_array($arrData['newsletter']))
        {
            $arrData['newsletter'] = array($arrData['newsletter']);
        }

        // Create user
        $objNewUser = $this->Database->prepare("INSERT INTO tl_member %s")->set($arrData)->execute();
        $insertId = $objNewUser->insertId;

        // HOOK: send insert ID and user data
        if (isset($GLOBALS['TL_HOOKS']['createNewUser']) && is_array($GLOBALS['TL_HOOKS']['createNewUser']))
        {
            foreach ($GLOBALS['TL_HOOKS']['createNewUser'] as $callback)
            {
                $this->import($callback[0]);
                $this->$callback[0]->$callback[1]($insertId, $arrData);
            }
        }

        $this->jumpToOrReload($this->jumpTo);
    }


    private function parse_signed_request($signed_request) {
        $secret = '77c26c54b7ec722da01ed7b7284fac34';
        list($encoded_sig, $payload) = explode('.', $signed_request, 2);

        // decode the data
        $sig = $this->base64_url_decode($encoded_sig);
        $data = json_decode($this->base64_url_decode($payload), true);

        if (strtoupper($data['algorithm']) !== 'HMAC-SHA256') {
            error_log('Unknown algorithm. Expected HMAC-SHA256');
            return null;
        }

        // check sig
        $expected_sig = hash_hmac('sha256', $payload, $secret, $raw = true);

        if ($sig !== $expected_sig) {
                error_log('Bad Signed JSON signature!');
                return null;
        }

        return $data;
    }

    private function base64_url_decode($input) {
        return base64_decode(strtr($input, '-_', '+/'));
    }
}