code:
<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * Base class for all actions (~views)
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Action
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @author    Sarven Capadisli <csarven@status.net>
 * @copyright 2008 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link      http://status.net/
 */

if (!defined('GNUSOCIAL')) {
    exit(1);
}

/**
 * Base class for all actions
 *
 * This is the base class for all actions in the package. An action is
 * more or less a "view" in an MVC framework.
 *
 * Actions are responsible for extracting and validating parameters; using
 * model classes to read and write to the database; and doing ouput.
 *
 * @category Output
 * @package  StatusNet
 * @author   Evan Prodromou <evan@status.net>
 * @author   Sarven Capadisli <csarven@status.net>
 * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link     http://status.net/
 *
 * @see      HTMLOutputter
 */
class Action extends HTMLOutputter // lawsuit
{
    // This should be protected/private in the future
    public $args = [];

    // Action properties, set per-class
    protected $action = false;
    protected $ajax = false;
    protected $menus = true;
    protected $needLogin = false;
    protected $redirectAfterLogin = false;
    protected $needPost = false;    // implies canPost if true
    protected $canPost = false;     // can this action handle POST method?

    // The currently scoped profile (normally Profile::current; from $this->auth_user for API)
    protected $scoped = null;

    // Related to front-end user representation
    protected $format = null;
    protected $error = null;
    protected $msg = null;

    /**
     * Constructor
     *
     * Just wraps the HTMLOutputter constructor.
     *
     * @param string $output URI to output to, default = stdout
     * @param boolean $indent Whether to indent output, default true
     *
     * @see XMLOutputter::__construct
     * @see HTMLOutputter::__construct
     */
    public function __construct($output = 'php://output', $indent = null)
    {
        parent::__construct($output, $indent);
    }

    public static function run(array $args = [], $output = 'php://output', $indent = null)
    {
        $class = get_called_class();
        $action = new $class($output, $indent);
        set_exception_handler(array($action, 'handleError'));
        $action->execute($args);
        return $action;
    }

    public function getInfo()
    {
        return $this->msg;
    }

    public function handleError($e)
    {
        if ($e instanceof ClientException) {
            $this->clientError($e->getMessage(), $e->getCode());
        } elseif ($e instanceof ServerException) {
            $this->serverError($e->getMessage(), $e->getCode());
        } else {
            // If it wasn't specified more closely which kind of exception it was
            $this->serverError($e->getMessage(), 500);
        }
    }

    /**
     * Client error
     *
     * @param string $msg error message to display
     * @param integer $code http error code, 400 by default
     * @param string $format error format (json, xml, text) for ApiAction
     *
     * @return void
     * @throws ClientException always
     */
    public function clientError($msg, $code = 400, $format = null)
    {
        // $format is currently only relevant for an ApiAction anyway
        if ($format === null) {
            $format = $this->format;
        }

        common_debug("User error '{$code}' on '{$this->action}': {$msg}", __FILE__);

        if (!array_key_exists($code, ClientErrorAction::$status)) {
            $code = 400;
        }

        $status_string = ClientErrorAction::$status[$code];

        switch ($format) {
            case 'xml':
                header("HTTP/1.1 {$code} {$status_string}");
                $this->initDocument('xml');
                $this->elementStart('hash');
                $this->element('error', null, $msg);
                $this->element('request', null, $_SERVER['REQUEST_URI']);
                $this->elementEnd('hash');
                $this->endDocument('xml');
                break;
            case 'json':
                if (!isset($this->callback)) {
                    header("HTTP/1.1 {$code} {$status_string}");
                }
                $this->initDocument('json');
                $error_array = array('error' => $msg, 'request' => $_SERVER['REQUEST_URI']);
                print(json_encode($error_array));
                $this->endDocument('json');
                break;
            case 'text':
                header("HTTP/1.1 {$code} {$status_string}");
                header('Content-Type: text/plain; charset=utf-8');
                echo $msg;
                break;
            default:
                common_log(LOG_ERR, 'Handled clientError (' . _ve($code) . ') but cannot output into desired format (' . _ve($this->format) . '): ' . _ve($msg));
                $action = new ClientErrorAction($msg, $code);
                $action->execute();
        }
        exit((int)$code);
    }

    public function execute(array $args = [])
    {
        // checkMirror stuff
        if (common_config('db', 'mirror') && $this->isReadOnly($args)) {
            if (is_array(common_config('db', 'mirror'))) {
                // "load balancing", ha ha
                $arr = common_config('db', 'mirror');
                $k = array_rand($arr);
                $mirror = $arr[$k];
            } else {
                $mirror = common_config('db', 'mirror');
            }

            // everyone else uses the mirror
            common_config_set('db', 'database', $mirror);
        }

        if (Event::handle('StartActionExecute', array($this, &$args))) {
            $prepared = $this->prepare($args);
            if ($prepared) {
                $this->handle();
            } else {
                common_debug('Prepare failed for Action.');
            }

            $this->flush();
            Event::handle('EndActionExecute', array($this));
        }
    }

    /**
     * Return true if read only.
     *
     * MAY override
     *
     * @param array $args other arguments
     *
     * @return boolean is read only action?
     */
    public function isReadOnly($args)
    {
        return false;
    }

    /**
     * For initializing members of the class.
     *
     * @param array $args misc. arguments
     *
     * @return boolean true
     * @throws ClientException
     */
    protected function prepare(array $args = [])
    {
        if ($this->needPost && !$this->isPost()) {
            // TRANS: Client error. POST is a HTTP command. It should not be translated.
            $this->clientError(_('This method requires a POST.'), 405);
        }

        // needPost, of course, overrides canPost if true
        if (!$this->canPost) {
            $this->canPost = $this->needPost;
        }

        $this->args = common_copy_args($args);

        // This could be set with get_called_action and then
        // chop off 'Action' from the class name. In lower case.
        $this->action = strtolower($this->trimmed('action'));

        if ($this->ajax || $this->boolean('ajax')) {
            // check with GNUsocial::isAjax()
            GNUsocial::setAjax(true);
        }

        if ($this->needLogin) {
            $this->checkLogin(); // if not logged in, this redirs/excepts
        }

        if ($this->redirectAfterLogin) {
            common_set_returnto($this->selfUrl());
        }

        $this->updateScopedProfile();

        return true;
    }

    /**
     * Check if the current request is a POST
     *
     * @return boolean true if POST; otherwise false.
     */

    public function isPost()
    {
        return ($_SERVER['REQUEST_METHOD'] == 'POST');
    }

    // Must be run _after_ prepare

    /**
     * Returns trimmed query argument or default value if not found
     *
     * @param string $key requested argument
     * @param string $def default value to return if $key is not provided
     *
     * @return boolean is read only action?
     */
    public function trimmed($key, $def = null)
    {
        $arg = $this->arg($key, $def);
        return is_string($arg) ? trim($arg) : $arg;
    }

    /**
     * Returns query argument or default value if not found
     *
     * @param string $key requested argument
     * @param string $def default value to return if $key is not provided
     *
     * @return boolean is read only action?
     */
    public function arg($key, $def = null)
    {
        if (array_key_exists($key, $this->args)) {
            return $this->args[$key];
        } else {
            return $def;
        }
    }

    /**
     * Boolean understands english (yes, no, true, false)
     *
     * @param string $key query key we're interested in
     * @param string $def default value
     *
     * @return boolean interprets yes/no strings as boolean
     */
    public function boolean($key, $def = false)
    {
        $arg = strtolower($this->trimmed($key));

        if (is_null($arg)) {
            return $def;
        } elseif (in_array($arg, array('true', 'yes', '1', 'on'))) {
            return true;
        } elseif (in_array($arg, array('false', 'no', '0'))) {
            return false;
        } else {
            return $def;
        }
    }

    /**
     * If not logged in, take appropriate action (redir or exception)
     *
     * @param boolean $redir Redirect to login if not logged in
     *
     * @return boolean true if logged in (never returns if not)
     * @throws ClientException
     */
    public function checkLogin($redir = true)
    {
        if (common_logged_in()) {
            return true;
        }

        if ($redir == true) {
            common_set_returnto($_SERVER['REQUEST_URI']);
            common_redirect(common_local_url('login'));
        }

        // TRANS: Error message displayed when trying to perform an action that requires a logged in user.
        $this->clientError(_('Not logged in.'), 403);
    }

    public function updateScopedProfile()
    {
        $this->scoped = Profile::current();
        return $this->scoped;
    }

    /**
     * Handler method
     */
    protected function handle()
    {
        header('Vary: Accept-Encoding,Cookie');

        $lm = $this->lastModified();
        $etag = $this->etag();

        if ($etag) {
            header('ETag: ' . $etag);
        }

        if ($lm) {
            header('Last-Modified: ' . date(DATE_RFC1123, $lm));
            if ($this->isCacheable()) {
                header('Expires: ' . gmdate('D, d M Y H:i:s', 0) . ' GMT');
                header("Cache-Control: private, must-revalidate, max-age=0");
                header("Pragma:");
            }
        }

        $checked = false;
        if ($etag) {
            $if_none_match = (array_key_exists('HTTP_IF_NONE_MATCH', $_SERVER)) ?
                $_SERVER['HTTP_IF_NONE_MATCH'] : null;
            if ($if_none_match) {
                // If this check fails, ignore the if-modified-since below.
                $checked = true;
                if ($this->_hasEtag($etag, $if_none_match)) {
                    header('HTTP/1.1 304 Not Modified');
                    // Better way to do this?
                    exit(0);
                }
            }
        }

        if (!$checked && $lm && array_key_exists('HTTP_IF_MODIFIED_SINCE', $_SERVER)) {
            $if_modified_since = $_SERVER['HTTP_IF_MODIFIED_SINCE'];
            $ims = strtotime($if_modified_since);
            if ($lm <= $ims) {
                header('HTTP/1.1 304 Not Modified');
                // Better way to do this?
                exit(0);
            }
        }
    }

    /**
     * Return last modified, if applicable.
     *
     * MAY override
     *
     * @return string last modified http header
     */
    public function lastModified()
    {
        // For comparison with If-Last-Modified
        // If not applicable, return null
        return null;
    }

    /**
     * Return etag, if applicable.
     *
     * MAY override
     *
     * @return string etag http header
     */
    public function etag()
    {
        return null;
    }

    /**
     * Is this action cacheable?
     *
     * If the action returns a last-modified
     *
     * @return boolean is read only action?
     */
    public function isCacheable()
    {
        return true;
    }

    /**
     * Has etag? (private)
     *
     * @param string $etag etag http header
     * @param string $if_none_match ifNoneMatch http header
     *
     * @return boolean
     */
    public function _hasEtag($etag, $if_none_match)
    {
        $etags = explode(',', $if_none_match);
        return in_array($etag, $etags) || in_array('*', $etags);
    }

    /**
     * Server error
     *
     * @param string $msg error message to display
     * @param integer $code http error code, 500 by default
     *
     * @param string $format
     * @return void
     */
    public function serverError($msg, $code = 500, $format = null)
    {
        if ($format === null) {
            $format = $this->format;
        }

        common_debug("Server error '{$code}' on '{$this->action}': {$msg}", __FILE__);

        if (!array_key_exists($code, ServerErrorAction::$status)) {
            $code = 500;
        }

        $status_string = ServerErrorAction::$status[$code];

        switch ($format) {
            case 'xml':
                header("HTTP/1.1 {$code} {$status_string}");
                $this->initDocument('xml');
                $this->elementStart('hash');
                $this->element('error', null, $msg);
                $this->element('request', null, $_SERVER['REQUEST_URI']);
                $this->elementEnd('hash');
                $this->endDocument('xml');
                break;
            case 'json':
                if (!isset($this->callback)) {
                    header("HTTP/1.1 {$code} {$status_string}");
                }
                $this->initDocument('json');
                $error_array = array('error' => $msg, 'request' => $_SERVER['REQUEST_URI']);
                print(json_encode($error_array));
                $this->endDocument('json');
                break;
            default:
                common_log(LOG_ERR, 'Handled serverError (' . _ve($code) . ') but cannot output into desired format (' . _ve($this->format) . '): ' . _ve($msg));
                $action = new ServerErrorAction($msg, $code);
                $action->execute();
        }

        exit((int)$code);
    }

    public function getScoped()
    {
        return ($this->scoped instanceof Profile) ? $this->scoped : null;
    }

    public function isAction(array $names)
    {
        foreach ($names as $class) {
            // PHP is case insensitive, and we have stuff like ApiUpperCaseAction,
            // but we at least make a point out of wanting to do stuff case-sensitive.
            $class = ucfirst($class) . 'Action';
            if ($this instanceof $class) {
                return true;
            }
        }
        return false;
    }

    /**
     * Show page, a template method.
     *
     * @return void
     * @throws ClientException
     * @throws ReflectionException
     * @throws ServerException
     */
    public function showPage()
    {
        if (GNUsocial::isAjax()) {
            self::showAjax();
            return;
        }
        if (Event::handle('StartShowHTML', array($this))) {
            $this->startHTML();
            $this->flush();
            Event::handle('EndShowHTML', array($this));
        }
        if (Event::handle('StartShowHead', array($this))) {
            $this->showHead();
            $this->flush();
            Event::handle('EndShowHead', array($this));
        }
        if (Event::handle('StartShowBody', array($this))) {
            $this->showBody();
            Event::handle('EndShowBody', array($this));
        }
        if (Event::handle('StartEndHTML', array($this))) {
            $this->endHTML();
            Event::handle('EndEndHTML', array($this));
        }
    }

    public function showAjax()
    {
        $this->startHTML('text/xml;charset=utf-8');
        $this->elementStart('head');
        // TRANS: Title for conversation page.
        $this->element('title', null, $this->title());
        $this->elementEnd('head');
        $this->elementStart('body');
        if ($this->getError()) {
            $this->element('p', array('id' => 'error'), $this->getError());
        } else {
            $this->showContent();
        }
        $this->elementEnd('body');
        $this->endHTML();
    }

    /**
     * Returns the page title
     *
     * SHOULD overload
     *
     * @return string page title
     */

    public function title()
    {
        // TRANS: Page title for a page without a title set.
        return _('Untitled page');
    }

    public function getError()
    {
        return $this->error;
    }

    /**
     * Show content.
     *
     * MUST overload (unless there's not a notice)
     *
     * @return void
     */
    protected function showContent()
    {
    }

    public function endHTML()
    {
        global $_startTime;

        if (isset($_startTime)) {
            $endTime = microtime(true);
            $diff = round(($endTime - $_startTime) * 1000);
            $this->raw("<!-- ${diff}ms -->");
        }

        parent::endHTML();
    }

    /**
     * Show head, a template method.
     *
     * @return void
     */
    public function showHead()
    {
        // XXX: attributes (profile?)
        $this->elementStart('head');
        if (Event::handle('StartShowHeadElements', array($this))) {
            if (Event::handle('StartShowHeadTitle', array($this))) {
                $this->showTitle();
                Event::handle('EndShowHeadTitle', array($this));
            }
            $this->showShortcutIcon();
            $this->showStylesheets();
            $this->showOpenSearch();
            $this->showFeeds();
            $this->showDescription();
            $this->extraHead();
            Event::handle('EndShowHeadElements', array($this));
        }
        $this->elementEnd('head');
    }

    /**
     * Show title, a template method.
     *
     * @return void
     */
    public function showTitle()
    {
        $this->element(
            'title',
            null,
            // TRANS: Page title. %1$s is the title, %2$s is the site name.
            sprintf(
                _('%1$s - %2$s'),
                $this->title(),
                common_config('site', 'name')
            )
        );
    }

    /**
     * Show themed shortcut icon
     *
     * @return void
     */
    public function showShortcutIcon()
    {
        if (is_readable(INSTALLDIR . '/theme/' . common_config('site', 'theme') . '/favicon.ico')) {
            $this->element('link', array('rel' => 'shortcut icon',
                'href' => Theme::path('favicon.ico')));
        } else {
            // favicon.ico should be HTTPS if the rest of the page is
            $this->element('link', array('rel' => 'shortcut icon',
                'href' => common_path('favicon.ico', GNUsocial::isHTTPS())));
        }

        if (common_config('site', 'mobile')) {
            if (is_readable(INSTALLDIR . '/theme/' . common_config('site', 'theme') . '/apple-touch-icon.png')) {
                $this->element('link', array('rel' => 'apple-touch-icon',
                    'href' => Theme::path('apple-touch-icon.png')));
            } else {
                $this->element('link', array('rel' => 'apple-touch-icon',
                    'href' => common_path('apple-touch-icon.png')));
            }
        }
    }

    /**
     * Show stylesheets
     *
     * @return void
     */
    public function showStylesheets()
    {
        if (Event::handle('StartShowStyles', array($this))) {

            // Use old name for StatusNet for compatibility on events

            if (Event::handle('StartShowStylesheets', array($this))) {
                $this->primaryCssLink(null, 'screen, projection, tv, print');
                Event::handle('EndShowStylesheets', array($this));
            }

            $this->cssLink('js/extlib/jquery-ui/css/smoothness/jquery-ui.css');

            if (Event::handle('StartShowUAStyles', array($this))) {
                Event::handle('EndShowUAStyles', array($this));
            }

            Event::handle('EndShowStyles', array($this));

            if (common_config('custom_css', 'enabled')) {
                $css = common_config('custom_css', 'css');
                if (Event::handle('StartShowCustomCss', array($this, &$css))) {
                    if (trim($css) != '') {
                        $this->style($css);
                    }
                    Event::handle('EndShowCustomCss', array($this));
                }
            }
        }
    }

    public function primaryCssLink($mainTheme = null, $media = null)
    {
        $theme = new Theme($mainTheme);

        // Some themes may have external stylesheets
        foreach ($theme->getExternals() as $url) {
            $this->cssLink($url, $mainTheme, $media);
        }

        // If the currently-selected theme has dependencies on other themes,
        // we'll need to load their display.css files as well in order.
        $baseThemes = $theme->getDeps();
        foreach ($baseThemes as $baseTheme) {
            $this->cssLink('css/display.css', $baseTheme, $media);
        }
        $this->cssLink('css/display.css', $mainTheme, $media);

        // Additional styles for RTL languages
        if (is_rtl(common_language())) {
            if (file_exists(Theme::file('css/rtl.css'))) {
                $this->cssLink('css/rtl.css', $mainTheme, $media);
            }
        }
    }

    /**
     * Show OpenSearch headers
     *
     * @return void
     */
    public function showOpenSearch()
    {
        $this->element('link', array('rel' => 'search',
            'type' => 'application/opensearchdescription+xml',
            'href' => common_local_url('opensearch', array('type' => 'people')),
            'title' => common_config('site', 'name') . ' People Search'));
        $this->element('link', array('rel' => 'search', 'type' => 'application/opensearchdescription+xml',
            'href' => common_local_url('opensearch', array('type' => 'notice')),
            'title' => common_config('site', 'name') . ' Notice Search'));
    }

    /**
     * Show feed headers
     *
     * MAY overload
     *
     * @return void
     */
    public function showFeeds()
    {
        foreach ($this->getFeeds() as $feed) {
            $this->element('link', array('rel' => $feed->rel(),
                'href' => $feed->url,
                'type' => $feed->mimeType(),
                'title' => $feed->title));
        }
    }

    /**
     * An array of feeds for this action.
     *
     * Returns an array of potential feeds for this action.
     *
     * @return array Feed object to show in head and links
     */
    public function getFeeds()
    {
        return [];
    }

    /**
     * Show description.
     *
     * SHOULD overload
     *
     * @return void
     */
    public function showDescription()
    {
        // does nothing by default
    }

    /**
     * Show extra stuff in <head>.
     *
     * MAY overload
     *
     * @return void
     */
    public function extraHead()
    {
        // does nothing by default
    }

    /**
     * Show body.
     *
     * Calls template methods
     *
     * @return void
     * @throws ServerException
     * @throws ReflectionException
     */
    public function showBody()
    {
        $params = array('id' => $this->getActionName());
        if ($this->scoped instanceof Profile) {
            $params['class'] = 'user_in';
        }
        $this->elementStart('body', $params);
        $this->elementStart('div', array('id' => 'wrap'));
        if (Event::handle('StartShowHeader', array($this))) {
            $this->showHeader();
            $this->flush();
            Event::handle('EndShowHeader', array($this));
        }
        $this->showCore();
        $this->flush();
        if (Event::handle('StartShowFooter', array($this))) {
            $this->showFooter();
            $this->flush();
            Event::handle('EndShowFooter', array($this));
        }
        $this->elementEnd('div');
        $this->showScripts();
        $this->elementEnd('body');
    }

    public function getActionName()
    {
        return $this->action;
    }

    /**
     * Show header of the page.
     *
     * Calls template methods
     *
     * @return void
     * @throws ServerException
     */
    public function showHeader()
    {
        $this->elementStart('div', array('id' => 'header'));
        $this->showLogo();
        $this->showPrimaryNav();
        if (Event::handle('StartShowSiteNotice', array($this))) {
            $this->showSiteNotice();

            Event::handle('EndShowSiteNotice', array($this));
        }

        $this->elementEnd('div');
    }

    /**
     * Show configured logo.
     *
     * @return void
     * @throws ServerException
     */
    public function showLogo()
    {
        $this->elementStart('address', array('id' => 'site_contact', 'class' => 'h-card'));
        if (Event::handle('StartAddressData', array($this))) {
            if (common_config('singleuser', 'enabled')) {
                $user = User::singleUser();
                $url = common_local_url(
                    'showstream',
                    array('nickname' => $user->nickname)
                );
            } elseif (common_logged_in()) {
                $cur = common_current_user();
                $url = common_local_url('all', array('nickname' => $cur->nickname));
            } else {
                $url = common_local_url('public');
            }

            $this->elementStart('a', array('class' => 'home bookmark',
                'href' => $url));

            if (GNUsocial::isHTTPS()) {
                $logoUrl = common_config('site', 'ssllogo');
                if (empty($logoUrl)) {
                    // if logo is an uploaded file, try to fall back to HTTPS file URL
                    $httpUrl = common_config('site', 'logo');
                    if (!empty($httpUrl)) {
                        try {
                            $f = File::getByUrl($httpUrl);
                            if (!empty($f->filename)) {
                                // this will handle the HTTPS case
                                $logoUrl = File::url($f->filename);
                            }
                        } catch (NoResultException $e) {
                            // no match
                        }
                    }
                }
            } else {
                $logoUrl = common_config('site', 'logo');
            }

            if (empty($logoUrl) && file_exists(Theme::file('logo.png'))) {
                // This should handle the HTTPS case internally
                $logoUrl = Theme::path('logo.png');
            }

            if (!empty($logoUrl)) {
                $this->element('img', array('class' => 'logo u-photo p-name',
                    'src' => $logoUrl,
                    'alt' => common_config('site', 'name')));
            }

            $this->elementEnd('a');

            Event::handle('EndAddressData', array($this));
        }
        $this->elementEnd('address');
    }

    /**
     * Show primary navigation.
     *
     * @return void
     */
    public function showPrimaryNav()
    {
        $this->elementStart('div', array('id' => 'site_nav_global_primary'));

        $user = common_current_user();

        if (!empty($user) || !common_config('site', 'private')) {
            $form = new SearchForm($this);
            $form->show();
        }

        $pn = new PrimaryNav($this);
        $pn->show();
        $this->elementEnd('div');
    }

    /**
     * Show site notice.
     *
     * @return void
     */
    public function showSiteNotice()
    {
        // Revist. Should probably do an hAtom pattern here
        $text = common_config('site', 'notice');
        if ($text) {
            $this->elementStart('div', array('id' => 'site_notice',
                'class' => 'system_notice'));
            $this->raw($text);
            $this->elementEnd('div');
        }
    }

    /**
     * Show core.
     *
     * Shows local navigation, content block and aside.
     *
     * @return void
     * @throws ReflectionException
     */
    public function showCore()
    {
        $this->elementStart('div', array('id' => 'core'));
        $this->elementStart('div', array('id' => 'aside_primary_wrapper'));
        $this->elementStart('div', array('id' => 'content_wrapper'));
        $this->elementStart('div', array('id' => 'site_nav_local_views_wrapper'));
        if (Event::handle('StartShowLocalNavBlock', array($this))) {
            $this->showLocalNavBlock();
            $this->flush();
            Event::handle('EndShowLocalNavBlock', array($this));
        }
        if (Event::handle('StartShowContentBlock', array($this))) {
            $this->showContentBlock();
            $this->flush();
            Event::handle('EndShowContentBlock', array($this));
        }
        if (Event::handle('StartShowAside', array($this))) {
            $this->showAside();
            $this->flush();
            Event::handle('EndShowAside', array($this));
        }
        $this->elementEnd('div');
        $this->elementEnd('div');
        $this->elementEnd('div');
        $this->elementEnd('div');
    }

    /**
     * Show local navigation block.
     *
     * @return void
     */
    public function showLocalNavBlock()
    {
        // Need to have this ID for CSS; I'm too lazy to add it to
        // all menus
        $this->elementStart('div', array('id' => 'site_nav_local_views'));
        // Cheat cheat cheat!
        $this->showLocalNav();
        $this->elementEnd('div');
    }

    /**
     * Show local navigation.
     *
     * SHOULD overload
     *
     * @return void
     */
    public function showLocalNav()
    {
        $nav = new DefaultLocalNav($this);
        $nav->show();
    }

    /**
     * Show content block.
     *
     * @return void
     * @throws ReflectionException
     */
    public function showContentBlock()
    {
        $this->elementStart('div', array('id' => 'content'));
        if (common_logged_in()) {
            if (Event::handle('StartShowNoticeForm', array($this))) {
                $this->showNoticeForm();
                Event::handle('EndShowNoticeForm', array($this));
            }
        }
        if (Event::handle('StartShowPageTitle', array($this))) {
            $this->showPageTitle();
            Event::handle('EndShowPageTitle', array($this));
        }
        $this->showPageNoticeBlock();
        $this->elementStart('div', array('id' => 'content_inner'));
        // show the actual content (forms, lists, whatever)
        $this->showContent();
        $this->elementEnd('div');
        $this->elementEnd('div');
    }

    /**
     * Show notice form.
     *
     * MAY overload if no notice form needed... or direct message box????
     *
     * @return void
     */
    public function showNoticeForm()
    {
        // TRANS: Tab on the notice form.
        $tabs = array('status' => array('title' => _m('TAB', 'Status'),
            'href' => common_local_url('newnotice')));

        $this->elementStart('div', 'input_forms');

        $this->element('label', array('for' => 'input_form_nav'), _m('TAB', 'Share your:'));

        if (Event::handle('StartShowEntryForms', array(&$tabs))) {
            $this->elementStart('ul', array('class' => 'nav',
                'id' => 'input_form_nav'));

            foreach ($tabs as $tag => $data) {
                $tag = htmlspecialchars($tag);
                $attrs = array('id' => 'input_form_nav_' . $tag,
                    'class' => 'input_form_nav_tab');

                if ($tag == 'status') {
                    $attrs['class'] .= ' current';
                }
                $this->elementStart('li', $attrs);

                $this->element(
                    'a',
                    array('onclick' => 'return SN.U.switchInputFormTab("' . $tag . '");',
                        'href' => $data['href']),
                    $data['title']
                );
                $this->elementEnd('li');
            }

            $this->elementEnd('ul');

            foreach ($tabs as $tag => $data) {
                $attrs = array('class' => 'input_form',
                    'id' => 'input_form_' . $tag);
                if ($tag == 'status') {
                    $attrs['class'] .= ' current';
                }

                $this->elementStart('div', $attrs);

                $form = null;

                if (Event::handle('StartMakeEntryForm', array($tag, $this, &$form))) {
                    if ($tag == 'status') {
                        $options = $this->noticeFormOptions();
                        $form = new NoticeForm($this, $options);
                    }
                    Event::handle('EndMakeEntryForm', array($tag, $this, $form));
                }

                if (!empty($form)) {
                    $form->show();
                }

                $this->elementEnd('div');
            }
        }

        $this->elementEnd('div');
    }

    public function noticeFormOptions()
    {
        return [];
    }

    /**
     * Show page title.
     *
     * @return void
     */
    public function showPageTitle()
    {
        $this->element('h1', null, $this->title());
    }

    /**
     * Show page notice block.
     *
     * Only show the block if a subclassed action has overrided
     * Action::showPageNotice(), or an event handler is registered for
     * the StartShowPageNotice event, in which case we assume the
     * 'page_notice' definition list is desired.  This is to prevent
     * empty 'page_notice' definition lists from being output everywhere.
     *
     * @return void
     * @throws ReflectionException
     */
    public function showPageNoticeBlock()
    {
        $rmethod = new ReflectionMethod($this, 'showPageNotice');
        $dclass = $rmethod->getDeclaringClass()->getName();

        if ($dclass != 'Action' || Event::hasHandler('StartShowPageNotice')) {
            $this->elementStart('div', array('id' => 'page_notice',
                'class' => 'system_notice'));
            if (Event::handle('StartShowPageNotice', array($this))) {
                $this->showPageNotice();
                Event::handle('EndShowPageNotice', array($this));
            }
            $this->elementEnd('div');
        }
    }

    /**
     * Show page notice.
     *
     * SHOULD overload (unless there's not a notice)
     *
     * @return void
     */
    public function showPageNotice()
    {
    }

    /**
     * Show Aside.
     *
     * @return void
     * @throws ReflectionException
     */
    public function showAside()
    {
        $this->elementStart('div', array('id' => 'aside_primary',
            'class' => 'aside'));
        $this->showProfileBlock();
        if (Event::handle('StartShowObjectNavBlock', array($this))) {
            $this->showObjectNavBlock();
            Event::handle('EndShowObjectNavBlock', array($this));
        }
        if (Event::handle('StartShowSections', array($this))) {
            $this->showSections();
            Event::handle('EndShowSections', array($this));
        }
        if (Event::handle('StartShowExportData', array($this))) {
            $this->showExportData();
            Event::handle('EndShowExportData', array($this));
        }
        $this->elementEnd('div');
    }

    /**
     * If there's a logged-in user, show a bit of login context
     *
     * @return void
     * @throws Exception
     */
    public function showProfileBlock()
    {
        if (common_logged_in()) {
            $block = new DefaultProfileBlock($this);
            $block->show();
        }
    }

    /**
     * Show menu for an object (group, profile)
     *
     * This block will only show if a subclass has overridden
     * the showObjectNav() method.
     *
     * @return void
     * @throws ReflectionException
     */
    public function showObjectNavBlock()
    {
        $rmethod = new ReflectionMethod($this, 'showObjectNav');
        $dclass = $rmethod->getDeclaringClass()->getName();

        if ($dclass != 'Action') {
            // Need to have this ID for CSS; I'm too lazy to add it to
            // all menus
            $this->elementStart('div', array('id' => 'site_nav_object',
                'class' => 'section'));
            $this->showObjectNav();
            $this->elementEnd('div');
        }
    }

    /**
     * Show object navigation.
     *
     * If there are things to do with this object, show it here.
     *
     * @return void
     */
    public function showObjectNav()
    {
        /* Nothing here. */
    }

    /**
     * Show sections.
     *
     * SHOULD overload
     *
     * @return void
     */
    public function showSections()
    {
        // for each section, show it
    }

    /**
     * Show export data feeds.
     *
     * @return void
     */
    public function showExportData()
    {
        $feeds = $this->getFeeds();
        if (!empty($feeds)) {
            $fl = new FeedList($this, $feeds);
            $fl->show();
        }
    }

    /**
     * Show footer.
     *
     * @return void
     */
    public function showFooter()
    {
        $this->elementStart('div', array('id' => 'footer'));
        if (Event::handle('StartShowInsideFooter', array($this))) {
            $this->showSecondaryNav();
            $this->showLicenses();
            Event::handle('EndShowInsideFooter', array($this));
        }
        $this->elementEnd('div');
    }

    /**
     * Show secondary navigation.
     *
     * @return void
     */
    public function showSecondaryNav()
    {
        $sn = new SecondaryNav($this);
        $sn->show();
    }

    /**
     * Show licenses.
     *
     * @return void
     */
    public function showLicenses()
    {
        $this->showGNUsocialLicense();
        $this->showContentLicense();
    }

    /**
     * Show GNU social license.
     *
     * @return void
     */
    public function showGNUsocialLicense()
    {
        if (common_config('site', 'broughtby')) {
            // TRANS: First sentence of the GNU social site license. Used if 'broughtby' is set.
            // TRANS: Text between [] is a link description, text between () is the link itself.
            // TRANS: Make sure there is no whitespace between "]" and "(".
            // TRANS: "%%site.broughtby%%" is the value of the variable site.broughtby
            $instr = _('**%%site.name%%** is a social network, courtesy of [%%site.broughtby%%](%%site.broughtbyurl%%).');
        } else {
            // TRANS: First sentence of the GNU social site license. Used if 'broughtby' is not set.
            $instr = _('**%%site.name%%** is a social network.');
        }
        $instr .= ' ';
        // TRANS: Second sentence of the GNU social site license. Mentions the GNU social source code license.
        // TRANS: Make sure there is no whitespace between "]" and "(".
        // TRANS: [%1$s](%2$s) is a link description followed by the link itself
        // TRANS: %3$s is the version of GNU social that is being used.
        $instr .= sprintf(_('It runs on [%1$s](%2$s), version %3$s, available under the [GNU Affero General Public License](http://www.fsf.org/licensing/licenses/agpl-3.0.html).'), GNUSOCIAL_ENGINE, GNUSOCIAL_ENGINE_URL, GNUSOCIAL_VERSION);
        $output = common_markup_to_html($instr);
        $this->raw($output);
        // do it
    }

    /**
     * Show content license.
     *
     * @return void
     */
    public function showContentLicense()
    {
        if (Event::handle('StartShowContentLicense', array($this))) {
            switch (common_config('license', 'type')) {
                case 'private':
                    // TRANS: Content license displayed when license is set to 'private'.
                    // TRANS: %1$s is the site name.
                    $this->element('p', null, sprintf(
                        _('Content and data of %1$s are private and confidential.'),
                        common_config('site', 'name')
                    ));
                // fall through
                // no break
                case 'allrightsreserved':
                    if (common_config('license', 'owner')) {
                        // TRANS: Content license displayed when license is set to 'allrightsreserved'.
                        // TRANS: %1$s is the copyright owner.
                        $this->element('p', null, sprintf(
                            _('Content and data copyright by %1$s. All rights reserved.'),
                            common_config('license', 'owner')
                        ));
                    } else {
                        // TRANS: Content license displayed when license is set to 'allrightsreserved' and no owner is set.
                        $this->element('p', null, _('Content and data copyright by contributors. All rights reserved.'));
                    }
                    break;
                case 'cc': // fall through
                default:
                    $this->elementStart('p');

                    $image = common_config('license', 'image');
                    $sslimage = common_config('license', 'sslimage');

                    if (GNUsocial::isHTTPS()) {
                        if (!empty($sslimage)) {
                            $url = $sslimage;
                        } elseif (preg_match('#^http://i.creativecommons.org/#', $image)) {
                            // CC support HTTPS on their images
                            $url = preg_replace('/^http/', 'https', $image, 1);
                        } else {
                            // Better to show mixed content than no content
                            $url = $image;
                        }
                    } else {
                        $url = $image;
                    }

                    $this->element('img', array('id' => 'license_cc',
                        'src' => $url,
                        'alt' => common_config('license', 'title'),
                        'width' => '80',
                        'height' => '15'));
                    $this->text(' ');
                    // TRANS: license message in footer.
                    // TRANS: %1$s is the site name, %2$s is a link to the license URL, with a licence name set in configuration.
                    $notice = _('All %1$s content and data are available under the %2$s license.');
                    $link = sprintf(
                        '<a class="license" rel="external license" href="%1$s">%2$s</a>',
                        htmlspecialchars(common_config('license', 'url')),
                        htmlspecialchars(common_config('license', 'title'))
                    );
                    $this->raw(@sprintf(
                        htmlspecialchars($notice),
                        htmlspecialchars(common_config('site', 'name')),
                        $link
                    ));
                    $this->elementEnd('p');
                    break;
            }

            Event::handle('EndShowContentLicense', array($this));
        }
    }

    /**
     * Show javascript headers
     *
     * @return void
     */
    public function showScripts()
    {
        if (Event::handle('StartShowScripts', array($this))) {
            if (Event::handle('StartShowJQueryScripts', array($this))) {
                $this->script('extlib/jquery.js');
                $this->script('extlib/jquery.form.js');
                $this->script('extlib/jquery-ui/jquery-ui.js');
                $this->script('extlib/jquery.cookie.js');

                Event::handle('EndShowJQueryScripts', array($this));
            }
            if (Event::handle('StartShowStatusNetScripts', array($this))) {
                $this->script('util.js');
                $this->script('xbImportNode.js');

                // This route isn't available in single-user mode.
                // Not sure why, but it causes errors here.
                $this->inlineScript('var _peopletagAC = "' .
                    common_local_url('peopletagautocomplete') . '";');
                $this->showScriptMessages();
                $this->showScriptVariables();
                // Anti-framing code to avoid clickjacking attacks in older browsers.
                // This will show a blank page if the page is being framed, which is
                // consistent with the behavior of the 'X-Frame-Options: SAMEORIGIN'
                // header, which prevents framing in newer browser.
                if (common_config('javascript', 'bustframes')) {
                    $this->inlineScript('if (window.top !== window.self) { document.write = ""; window.top.location = window.self.location; setTimeout(function () { document.body.innerHTML = ""; }, 1); window.self.onload = function () { document.body.innerHTML = ""; }; }');
                }
                Event::handle('EndShowStatusNetScripts', array($this));
            }
            Event::handle('EndShowScripts', array($this));
        }
    }

    /**
     * Exports a map of localized text strings to JavaScript code.
     *
     * Plugins can add to what's exported by hooking the StartScriptMessages or EndScriptMessages
     * events and appending to the array. Try to avoid adding strings that won't be used, as
     * they'll be added to HTML output.
     */
    public function showScriptMessages()
    {
        $messages = [];

        if (Event::handle('StartScriptMessages', array($this, &$messages))) {
            // Common messages needed for timeline views etc...

            // TRANS: Localized tooltip for '...' expansion button on overlong remote messages.
            $messages['showmore_tooltip'] = _m('TOOLTIP', 'Show more');
            $messages['popup_close_button'] = _m('TOOLTIP', 'Close popup');

            $messages = array_merge($messages, $this->getScriptMessages());

            Event::handle('EndScriptMessages', array($this, &$messages));
        }

        if (!empty($messages)) {
            $this->inlineScript('SN.messages=' . json_encode($messages));
        }

        return $messages;
    }

    /**
     * If the action will need localizable text strings, export them here like so:
     *
     * return array('pool_deepend' => _('Deep end'),
     *              'pool_shallow' => _('Shallow end'));
     *
     * The exported map will be available via SN.msg() to JS code:
     *
     *   $('#pool').html('<div class="deepend"></div><div class="shallow"></div>');
     *   $('#pool .deepend').text(SN.msg('pool_deepend'));
     *   $('#pool .shallow').text(SN.msg('pool_shallow'));
     *
     * Exports a map of localized text strings to JavaScript code.
     *
     * Plugins can add to what's exported on any action by hooking the StartScriptMessages or
     * EndScriptMessages events and appending to the array. Try to avoid adding strings that won't
     * be used, as they'll be added to HTML output.
     */
    public function getScriptMessages()
    {
        return [];
    }

    protected function showScriptVariables()
    {
        $vars = [];

        if (Event::handle('StartScriptVariables', array($this, &$vars))) {
            $vars['urlNewNotice'] = common_local_url('newnotice');
            $vars['xhrTimeout'] = ini_get('max_execution_time') * 1000;   // milliseconds
            Event::handle('EndScriptVariables', array($this, &$vars));
        }

        $this->inlineScript('SN.V = ' . json_encode($vars) . ';');

        return $vars;
    }

    /**
     * Show anonymous message.
     *
     * SHOULD overload
     *
     * @return void
     */
    public function showAnonymousMessage()
    {
        // needs to be defined by the class
    }

    /**
     * This is a cheap hack to avoid a bug in DB_DataObject
     * where '' is non-type-aware compared to 0, which means it
     * will always be true for values like false and 0 too...
     *
     * Upstream bug is::
     * https://pear.php.net/bugs/bug.php?id=20291
     */
    public function booleanintstring($key, $def = false)
    {
        return $this->boolean($key, $def) ? '1' : '0';
    }

    /**
     * Integer value of an argument
     *
     * @param string $key query key we're interested in
     * @param string $defValue optional default value (default null)
     * @param string $maxValue optional max value (default null)
     * @param string $minValue optional min value (default null)
     *
     * @return integer integer value
     */
    public function int($key, $defValue = null, $maxValue = null, $minValue = null)
    {
        $arg = intval($this->arg($key));

        if (!is_numeric($this->arg($key)) || $arg != $this->arg($key)) {
            return $defValue;
        }

        if (!is_null($maxValue)) {
            $arg = min($arg, $maxValue);
        }

        if (!is_null($minValue)) {
            $arg = max($arg, $minValue);
        }

        return $arg;
    }

    /**
     * Returns the current URL
     *
     * @return string current URL
     */
    public function selfUrl()
    {
        list($action, $args) = $this->returnToArgs();
        return common_local_url($action, $args);
    }

    /**
     * Generate pagination links
     *
     * @param boolean $have_before is there something before?
     * @param boolean $have_after is there something after?
     * @param integer $page current page
     * @param string $action current action
     * @param array $args rest of query arguments
     *
     * @return void
     */
    // XXX: The messages in this pagination method only tailor to navigating
    //      notices. In other lists, "Previous"/"Next" type navigation is
    //      desirable, but not available.
    /**
     * Returns arguments sufficient for re-constructing URL
     *
     * @return array two elements: action, other args
     */
    public function returnToArgs()
    {
        $action = $this->getActionName();
        $args = $this->args;
        unset($args['action']);
        if (common_config('site', 'fancy')) {
            unset($args['p']);
        }
        if (array_key_exists('submit', $args)) {
            unset($args['submit']);
        }
        foreach (array_keys($_COOKIE) as $cookie) {
            unset($args[$cookie]);
        }
        return array($action, $args);
    }

    /**
     * Generate a menu item
     *
     * @param string $url menu URL
     * @param string $text menu name
     * @param string $title title attribute, null by default
     * @param boolean $is_selected current menu item, false by default
     * @param string $id element id, null by default
     *
     * @return void
     */
    public function menuItem($url, $text, $title = null, $is_selected = false, $id = null, $class = null)
    {
        // Added @id to li for some control.
        // XXX: We might want to move this to htmloutputter.php
        $lattrs = [];
        $classes = [];
        if ($class !== null) {
            $classes[] = trim($class);
        }
        if ($is_selected) {
            $classes[] = 'current';
        }

        if (!empty($classes)) {
            $lattrs['class'] = implode(' ', $classes);
        }

        if (!is_null($id)) {
            $lattrs['id'] = $id;
        }

        $this->elementStart('li', $lattrs);
        $attrs['href'] = $url;
        if ($title) {
            $attrs['title'] = $title;
        }
        $this->element('a', $attrs, $text);
        $this->elementEnd('li');
    }

    /**
     * Check the session token.
     *
     * Checks that the current form has the correct session token,
     * and throw an exception if it does not.
     *
     * @return void
     */
    // XXX: Finding this type of check with the same message about 50 times.
    //      Possible to refactor?

    public function pagination($have_before, $have_after, $page, $action, $args = null)
    {
        // Does a little before-after block for next/prev page
        if ($have_before || $have_after) {
            $this->elementStart('ul', array('class' => 'nav',
                'id' => 'pagination'));
        }
        if ($have_before) {
            $pargs = array('page' => $page - 1);
            $this->elementStart('li', array('class' => 'nav_prev'));
            $this->element(
                'a',
                array('href' => common_local_url($action, $args, $pargs),
                    'rel' => 'prev'),
                // TRANS: Pagination message to go to a page displaying information more in the
                // TRANS: present than the currently displayed information.
                _('After')
            );
            $this->elementEnd('li');
        }
        if ($have_after) {
            $pargs = array('page' => $page + 1);
            $this->elementStart('li', array('class' => 'nav_next'));
            $this->element(
                'a',
                array('href' => common_local_url($action, $args, $pargs),
                    'rel' => 'next'),
                // TRANS: Pagination message to go to a page displaying information more in the
                // TRANS: past than the currently displayed information.
                _('Before')
            );
            $this->elementEnd('li');
        }
        if ($have_before || $have_after) {
            $this->elementEnd('ul');
        }
    }

    public function checkSessionToken()
    {
        // CSRF protection
        $token = $this->trimmed('token');
        if (empty($token) || $token != common_session_token()) {
            // TRANS: Client error text when there is a problem with the session token.
            $this->clientError(_('There was a problem with your session token.'));
        }
    }
}


code:
<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * An activity
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Feed
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @author    Zach Copley <zach@status.net>
 * @copyright 2010 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
 * @link      http://status.net/
 */

if (!defined('STATUSNET')) {
    exit(1);
}

/**
 * An activity in the ActivityStrea.ms world
 *
 * An activity is kind of like a sentence: someone did something
 * to something else.
 *
 * 'someone' is the 'actor'; 'did something' is the verb;
 * 'something else' is the object.
 *
 * @category  OStatus
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @copyright 2010 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
 * @link      http://status.net/
 */
class Activity
{
    const SPEC   = 'http://activitystrea.ms/spec/1.0/';
    const SCHEMA = 'http://activitystrea.ms/schema/1.0/';
    const MEDIA  = 'http://purl.org/syndication/atommedia';

    const VERB       = 'verb';
    const OBJECT     = 'object';
    const ACTOR      = 'actor';
    const SUBJECT    = 'subject';
    const OBJECTTYPE = 'object-type';
    const CONTEXT    = 'context';
    const TARGET     = 'target';

    const ATOM = 'http://www.w3.org/2005/Atom';

    const AUTHOR    = 'author';
    const PUBLISHED = 'published';
    const UPDATED   = 'updated';

    const RSS = null; // no namespace!

    const PUBDATE     = 'pubDate';
    const DESCRIPTION = 'description';
    const GUID        = 'guid';
    const SELF        = 'self';
    const IMAGE       = 'image';
    const URL         = 'url';

    const DC = 'http://purl.org/dc/elements/1.1/';

    const CREATOR = 'creator';

    const CONTENTNS = 'http://purl.org/rss/1.0/modules/content/';
    const ENCODED = 'encoded';

    public $actor;   // an ActivityObject
    public $verb;    // a string (the URL)
    public $objects = array();  // an array of ActivityObjects
    public $target;  // an ActivityObject
    public $context; // an ActivityObject
    public $time;    // Time of the activity
    public $link;    // an ActivityObject
    public $entry;   // the source entry
    public $feed;    // the source feed

    public $summary; // summary of activity
    public $content; // HTML content of activity
    public $id;      // ID of the activity
    public $title;   // title of the activity
    public $categories = array(); // list of AtomCategory objects
    public $enclosures = array(); // list of enclosure URL references
    public $attachments = array(); // list of attachments

    public $extra = array(); // extra elements as array(tag, attrs, content)
    public $source;  // ActivitySource object representing 'home feed'
    public $selfLink; // <link rel='self' type='application/atom+xml'>
    public $editLink; // <link rel='edit' type='application/atom+xml'>
    public $generator; // ActivityObject representing the generating application
    /**
     * Turns a regular old Atom <entry> into a magical activity
     *
     * @param DOMElement $entry Atom entry to poke at
     * @param DOMElement $feed  Atom feed, for context
     */
    function __construct($entry = null, $feed = null)
    {
        if (is_null($entry)) {
            return;
        }

        // Insist on a feed's root DOMElement; don't allow a DOMDocument
        if ($feed instanceof DOMDocument) {
            throw new ClientException(
                // TRANS: Client exception thrown when a feed instance is a DOMDocument.
                _('Expecting a root feed element but got a whole XML document.')
            );
        }

        $this->entry = $entry;
        $this->feed  = $feed;

        if ($entry->namespaceURI == Activity::ATOM &&
            $entry->localName == 'entry') {
            $this->_fromAtomEntry($entry, $feed);
        } else if ($entry->namespaceURI == Activity::RSS &&
                   $entry->localName == 'item') {
            $this->_fromRssItem($entry, $feed);
        } else if ($entry->namespaceURI == Activity::SPEC &&
                   $entry->localName == 'object') {
            $this->_fromAtomEntry($entry, $feed);
        } else {
            // Low level exception. No need for i18n.
            throw new Exception("Unknown DOM element: {$entry->namespaceURI} {$entry->localName}");
        }
    }

    function _fromAtomEntry($entry, $feed)
    {
        $pubEl = $this->_child($entry, self::PUBLISHED, self::ATOM);

        if (!empty($pubEl)) {
            $this->time = strtotime($pubEl->textContent);
        } else {
            // XXX technically an error; being liberal. Good idea...?
            $updateEl = $this->_child($entry, self::UPDATED, self::ATOM);
            if (!empty($updateEl)) {
                $this->time = strtotime($updateEl->textContent);
            } else {
                $this->time = null;
            }
        }

        $this->link = ActivityUtils::getPermalink($entry);

        $verbEl = $this->_child($entry, self::VERB);

        if (!empty($verbEl)) {
            $this->verb = trim($verbEl->textContent);
        } else {
            $this->verb = ActivityVerb::POST;
            // XXX: do other implied stuff here
        }

        // get immediate object children

        $objectEls = ActivityUtils::children($entry, self::OBJECT, self::SPEC);

        if (count($objectEls) > 0) {
            foreach ($objectEls as $objectEl) {
                // Special case for embedded activities
                $objectType = ActivityUtils::childContent($objectEl, self::OBJECTTYPE, self::SPEC);
                if ((!empty($objectType) && $objectType == ActivityObject::ACTIVITY) || $this->verb == ActivityVerb::SHARE) {
                    $this->objects[] = new Activity($objectEl);
                } else {
                    $this->objects[] = new ActivityObject($objectEl);
                }
            }
        } else {
            // XXX: really?
            $this->objects[] = new ActivityObject($entry);
        }

        $actorEl = $this->_child($entry, self::ACTOR);

        if (!empty($actorEl)) {
            // Standalone <activity:actor> elements are a holdover from older
            // versions of ActivityStreams. Newer feeds should have this data
            // integrated straight into <atom:author>.

            $this->actor = new ActivityObject($actorEl);

            // Cliqset has bad actor IDs (just nickname of user). We
            // work around it by getting the author data and using its
            // id instead

            if (!preg_match('/^\w+:/', $this->actor->id)) {
                $authorEl = ActivityUtils::child($entry, 'author');
                if (!empty($authorEl)) {
                    $authorObj = new ActivityObject($authorEl);
                    $this->actor->id = $authorObj->id;
                }
            }
        } else if ($authorEl = $this->_child($entry, self::AUTHOR, self::ATOM)) {

            // An <atom:author> in the entry overrides any author info on
            // the surrounding feed.
            $this->actor = new ActivityObject($authorEl);

        } else if (!empty($feed) &&
                   $subjectEl = $this->_child($feed, self::SUBJECT)) {

            // Feed subject is used for things like groups.
            // Should actually possibly not be interpreted as an actor...?
            $this->actor = new ActivityObject($subjectEl);

        } else if (!empty($feed) && $authorEl = $this->_child($feed, self::AUTHOR,
                                                              self::ATOM)) {

            // If there's no <atom:author> on the entry, it's safe to assume
            // the containing feed's authorship info applies.
            $this->actor = new ActivityObject($authorEl);
        }

        $contextEl = $this->_child($entry, self::CONTEXT);

        if (!empty($contextEl)) {
            $this->context = new ActivityContext($contextEl);
        } else {
            $this->context = new ActivityContext($entry);
        }

        $targetEl = $this->_child($entry, self::TARGET);

        if (!empty($targetEl)) {
            $this->target = new ActivityObject($targetEl);
        } elseif (ActivityUtils::compareVerbs($this->verb, array(ActivityVerb::FAVORITE))) {
            // StatusNet didn't send a 'target' for their Favorite atom entries
            $this->target = clone($this->objects[0]);
        }

        $this->summary = ActivityUtils::childContent($entry, 'summary');
        $this->id      = ActivityUtils::childContent($entry, 'id');
        $this->content = ActivityUtils::getContent($entry);

        $catEls = $entry->getElementsByTagNameNS(self::ATOM, 'category');
        if ($catEls) {
            for ($i = 0; $i < $catEls->length; $i++) {
                $catEl = $catEls->item($i);
                $this->categories[] = new AtomCategory($catEl);
            }
        }

        foreach (ActivityUtils::getLinks($entry, 'enclosure') as $link) {
            $this->enclosures[] = $link->getAttribute('href');
        }

        // From APP. Might be useful.

        $this->selfLink = ActivityUtils::getSelfLink($entry);
        $this->editLink = ActivityUtils::getLink($entry, 'edit', 'application/atom+xml');
    }

    function _fromRssItem($item, $channel)
    {
        $verbEl = $this->_child($item, self::VERB);

        if (!empty($verbEl)) {
            $this->verb = trim($verbEl->textContent);
        } else {
            $this->verb = ActivityVerb::POST;
            // XXX: do other implied stuff here
        }

        $pubDateEl = $this->_child($item, self::PUBDATE, self::RSS);

        if (!empty($pubDateEl)) {
            $this->time = strtotime($pubDateEl->textContent);
        }

        if ($authorEl = $this->_child($item, self::AUTHOR, self::RSS)) {
            $this->actor = ActivityObject::fromRssAuthor($authorEl);
        } else if ($dcCreatorEl = $this->_child($item, self::CREATOR, self::DC)) {
            $this->actor = ActivityObject::fromDcCreator($dcCreatorEl);
        } else if ($posterousEl = $this->_child($item, ActivityObject::AUTHOR, ActivityObject::POSTEROUS)) {
            // Special case for Posterous.com
            $this->actor = ActivityObject::fromPosterousAuthor($posterousEl);
        } else if (!empty($channel)) {
            $this->actor = ActivityObject::fromRssChannel($channel);
        } else {
            // No actor!
        }

        $this->title = ActivityUtils::childContent($item, ActivityObject::TITLE, self::RSS);

        $contentEl = ActivityUtils::child($item, self::ENCODED, self::CONTENTNS);

        if (!empty($contentEl)) {
            // <content:encoded> XML node's text content is HTML; no further processing needed.
            $this->content = $contentEl->textContent;
        } else {
            $descriptionEl = ActivityUtils::child($item, self::DESCRIPTION, self::RSS);
            if (!empty($descriptionEl)) {
                // Per spec, <description> must be plaintext.
                // In practice, often there's HTML... but these days good
                // feeds are using <content:encoded> which is explicitly
                // real HTML.
                // We'll treat this following spec, and do HTML escaping
                // to convert from plaintext to HTML.
                $this->content = htmlspecialchars($descriptionEl->textContent);
            }
        }

        $this->link = ActivityUtils::childContent($item, ActivityUtils::LINK, self::RSS);

        // @fixme enclosures
        // @fixme thumbnails... maybe

        $guidEl = ActivityUtils::child($item, self::GUID, self::RSS);

        if (!empty($guidEl)) {
            $this->id = $guidEl->textContent;

            if ($guidEl->hasAttribute('isPermaLink') && $guidEl->getAttribute('isPermaLink') != 'false') {
                // overwrites <link>
                $this->link = $this->id;
            }
        }

        $this->objects[] = new ActivityObject($item);
        $this->context   = new ActivityContext($item);
    }

    /**
     * Returns an Atom <entry> based on this activity
     *
     * @return DOMElement Atom entry
     */

    function toAtomEntry()
    {
        return null;
    }

    /**
     * Returns an array based on this activity suitable
     * for encoding as a JSON object
     *
     * @return array $activity
     */

    function asArray()
    {
        $activity = array();

        // actor
        $activity['actor'] = $this->actor->asArray();

        // content
        $activity['content'] = $this->content;

        // generator

        if (!empty($this->generator)) {
            $activity['generator'] = $this->generator->asArray();
        }

        // icon <-- possibly a mini object representing verb?

        // id
        $activity['id'] = $this->id;

        // object

        if (count($this->objects) == 0) {
            common_log(LOG_ERR, "Can't save " . $this->id);
        } else {
            if (count($this->objects) > 1) {
                common_log(LOG_WARNING, "Ignoring " . (count($this->objects) - 1) . " extra objects in JSON output for activity " . $this->id);
            }
            $object = $this->objects[0];

            if ($object instanceof Activity) {
                // Sharing a post activity is more like sharing the original object
                if (ActivityVerb::canonical($this->verb) == ActivityVerb::canonical(ActivityVerb::SHARE) &&
                    ActivityVerb::canonical($object->verb) == ActivityVerb::canonical(ActivityVerb::POST)) {
                    // XXX: Here's one for the obfuscation record books
                    $object = $object->objects[0];
                }
            }

            $activity['object'] = $object->asArray();

            if ($object instanceof Activity) {
                $activity['object']['objectType'] = 'activity';
            }

            foreach ($this->attachments as $attachment) {
                if (empty($activity['object']['attachments'])) {
                    $activity['object']['attachments'] = array();
                }
                $activity['object']['attachments'][] = $attachment->asArray();
            }
        }

        // Context stuff.

        if (!empty($this->context)) {

            if (!empty($this->context->location)) {
                $loc = $this->context->location;

                $activity['location'] = array(
                    'objectType' => 'place',
                    'position' => sprintf("%+02.5F%+03.5F/", $loc->lat, $loc->lon),
                    'lat' => $loc->lat,
                    'lon' => $loc->lon
                );

                $name = $loc->getName();

                if ($name) {
                    $activity['location']['displayName'] = $name;
                }

                $url = $loc->getURL();

                if ($url) {
                    $activity['location']['url'] = $url;
                }
            }

            $activity['to']      = $this->context->getToArray();

            $ctxarr = $this->context->asArray();

            if (array_key_exists('inReplyTo', $ctxarr)) {
                $activity['object']['inReplyTo'] = $ctxarr['inReplyTo'];
                unset($ctxarr['inReplyTo']);
            }

            if (!array_key_exists('status_net', $activity)) {
                $activity['status_net'] = array();
            }

            foreach ($ctxarr as $key => $value) {
                $activity['status_net'][$key] = $value;
            }
        }

        // published
        $activity['published'] = self::iso8601Date($this->time);

        // provider
        $provider = array(
            'objectType' => 'service',
            'displayName' => common_config('site', 'name'),
            'url' => common_root_url()
        );

        $activity['provider'] = $provider;

        // target
        if (!empty($this->target)) {
            $activity['target'] = $this->target->asArray();
        }

        // title
        $activity['title'] = $this->title;

        // updated <-- Optional. Should we use this to indicate the time we r
        //             eceived a remote notice? Probably not.

        // verb

        $activity['verb'] = ActivityVerb::canonical($this->verb);

        // url
        if ($this->link) {
            $activity['url'] = $this->link;
        }

        /* Purely extensions hereafter */

        if ($activity['verb'] == 'post') {
            $tags = array();
            foreach ($this->categories as $cat) {
                if (mb_strlen($cat->term) > 0) {
                    // Couldn't figure out which object type to use, so...
                    $tags[] = array('objectType' => 'http://activityschema.org/object/hashtag',
                                    'displayName' => $cat->term);
                }
            }
            if (count($tags) > 0) {
                $activity['object']['tags'] = $tags;
            }
        }

        // XXX: a bit of a hack... Since JSON isn't namespaced we probably
        // shouldn't be using 'statusnet:notice_info', but this will work
        // for the moment.

        foreach ($this->extra as $e) {
            list($objectName, $props, $txt) = $e;
            if (!empty($objectName)) {
                $parts = explode(":", $objectName);
                if (count($parts) == 2 && $parts[0] == "statusnet") {
                    if (!array_key_exists('status_net', $activity)) {
                        $activity['status_net'] = array();
                    }
                    $activity['status_net'][$parts[1]] = $props;
                } else {
                    $activity[$objectName] = $props;
                }
            }
        }

        return array_filter($activity);
    }

    function asString($namespace=false, $author=true, $source=false)
    {
        $xs = new XMLStringer(true);
        $this->outputTo($xs, $namespace, $author, $source);
        return $xs->getString();
    }

    function outputTo($xs, $namespace=false, $author=true, $source=false, $tag='entry')
    {
        if ($namespace) {
            $attrs = array('xmlns' => 'http://www.w3.org/2005/Atom',
                           'xmlns:thr' => 'http://purl.org/syndication/thread/1.0',
                           'xmlns:activity' => 'http://activitystrea.ms/spec/1.0/',
                           'xmlns:georss' => 'http://www.georss.org/georss',
                           'xmlns:ostatus' => 'http://ostatus.org/schema/1.0',
                           'xmlns:poco' => 'http://portablecontacts.net/spec/1.0',
                           'xmlns:media' => 'http://purl.org/syndication/atommedia',
                           'xmlns:statusnet' => 'http://status.net/schema/api/1/');
        } else {
            $attrs = array();
        }

        $xs->elementStart($tag, $attrs);

        if ($tag != 'entry') {
            $xs->element('activity:object-type', null, ActivityObject::ACTIVITY);
        }

        if ($this->verb == ActivityVerb::POST && count($this->objects) == 1 && $tag == 'entry') {

            $obj = $this->objects[0];
			$obj->outputTo($xs, null);

        } else {
            $xs->element('id', null, $this->id);

            if ($this->title) {
                $xs->element('title', null, $this->title);
            } else {
                // Require element
                $xs->element('title', null, "");
            }

            $xs->element('content', array('type' => 'html'), $this->content);

            if (!empty($this->summary)) {
                $xs->element('summary', null, $this->summary);
            }

            if (!empty($this->link)) {
                $xs->element('link', array('rel' => 'alternate',
                                           'type' => 'text/html',
                                           'href' => $this->link));
            }

        }

        $xs->element('activity:verb', null, $this->verb);

        $published = self::iso8601Date($this->time);

        $xs->element('published', null, $published);
        $xs->element('updated', null, $published);

        if ($author) {
            $this->actor->outputTo($xs, 'author');
        }

        if ($this->verb != ActivityVerb::POST || count($this->objects) != 1 || $tag != 'entry') {
            foreach($this->objects as $object) {
                if ($object instanceof Activity) {
                    $object->outputTo($xs, false, true, true, 'activity:object');
                } else {
                    $object->outputTo($xs, 'activity:object');
                }
            }
        }

        if (!empty($this->context)) {

            if (!empty($this->context->replyToID)) {
                if (!empty($this->context->replyToUrl)) {
                    $xs->element('thr:in-reply-to',
                                 array('ref' => $this->context->replyToID,
                                       'href' => $this->context->replyToUrl));
                } else {
                    $xs->element('thr:in-reply-to',
                                 array('ref' => $this->context->replyToID));
                }
            }

            if (!empty($this->context->replyToUrl)) {
                $xs->element('link', array('rel' => 'related',
                                           'href' => $this->context->replyToUrl));
            }

            if (!empty($this->context->conversation)) {
                $convattr = [];
                $conv = Conversation::getKV('uri', $this->context->conversation);
                if ($conv instanceof Conversation) {
                    $convattr['href'] = $conv->getUrl();
                    $convattr['local_id'] = $conv->getID();
                    $convattr['ref'] = $conv->getUri();
                    $xs->element('link', array('rel' => 'ostatus:'.ActivityContext::CONVERSATION,
                                                'href' => $convattr['href']));
                } else {
                    $convattr['ref'] = $this->context->conversation;
                }
                $xs->element('ostatus:'.ActivityContext::CONVERSATION,
                                $convattr,
                                $this->context->conversation);
                /* Since we use XMLWriter we just use the previously hardcoded prefix for ostatus,
                    otherwise we should use something like this:
                $xs->elementNS(array(ActivityContext::OSTATUS => 'ostatus'),    // namespace
                                ActivityContext::CONVERSATION,
                                null,   // attributes
                                $this->context->conversation);  // content
                */
            }

            foreach ($this->context->attention as $attnURI=>$type) {
                $xs->element('link', array('rel' => ActivityContext::MENTIONED,
                                           ActivityContext::OBJECTTYPE => $type,  // FIXME: undocumented
                                           'href' => $attnURI));
            }

            if (!empty($this->context->location)) {
                $loc = $this->context->location;
                $xs->element('georss:point', null, $loc->lat . ' ' . $loc->lon);
            }
        }

        if ($this->target) {
            $this->target->outputTo($xs, 'activity:target');
        }

        foreach ($this->categories as $cat) {
            $cat->outputTo($xs);
        }

        // can be either URLs or enclosure objects

        foreach ($this->enclosures as $enclosure) {
            if (is_string($enclosure)) {
                $xs->element('link', array('rel' => 'enclosure',
                                           'href' => $enclosure));
            } else {
                $attributes = array('rel' => 'enclosure',
                                    'href' => $enclosure->url,
                                    'type' => $enclosure->mimetype,
                                    'length' => $enclosure->size);
                if ($enclosure->title) {
                    $attributes['title'] = $enclosure->title;
                }
                $xs->element('link', $attributes);
            }
        }

        // Info on the source feed

        if ($source && !empty($this->source)) {
            $xs->elementStart('source');

            $xs->element('id', null, $this->source->id);
            $xs->element('title', null, $this->source->title);

            if (array_key_exists('alternate', $this->source->links)) {
                $xs->element('link', array('rel' => 'alternate',
                                           'type' => 'text/html',
                                           'href' => $this->source->links['alternate']));
            }

            if (array_key_exists('self', $this->source->links)) {
                $xs->element('link', array('rel' => 'self',
                                           'type' => 'application/atom+xml',
                                           'href' => $this->source->links['self']));
            }

            if (array_key_exists('license', $this->source->links)) {
                $xs->element('link', array('rel' => 'license',
                                           'href' => $this->source->links['license']));
            }

            if (!empty($this->source->icon)) {
                $xs->element('icon', null, $this->source->icon);
            }

            if (!empty($this->source->updated)) {
                $xs->element('updated', null, $this->source->updated);
            }

            $xs->elementEnd('source');
        }

        if (!empty($this->selfLink)) {
            $xs->element('link', array('rel' => 'self',
                                       'type' => 'application/atom+xml',
                                       'href' => $this->selfLink));
        }

        if (!empty($this->editLink)) {
            $xs->element('link', array('rel' => 'edit',
                                       'type' => 'application/atom+xml',
                                       'href' => $this->editLink));
        }

        // For throwing in extra elements; used for statusnet:notice_info

        foreach ($this->extra as $el) {
            list($tag, $attrs, $content) = $el;
            $xs->element($tag, $attrs, $content);
        }

        $xs->elementEnd($tag);

        return;
    }

    private function _child($element, $tag, $namespace=self::SPEC)
    {
        return ActivityUtils::child($element, $tag, $namespace);
    }

    /**
     * For consistency, we'll always output UTC rather than local time.
     * Note that clients *should* accept any timezone we give them as long
     * as it's properly formatted.
     *
     * @param int $tm Unix timestamp
     * @return string
     */
    static function iso8601Date($tm)
    {
        $dateStr = date('d F Y H:i:s', $tm);
        $d = new DateTime($dateStr, new DateTimeZone('UTC'));
        return $d->format('c');
    }
}

license: mit


code:
<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * An activity
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Feed
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @author    Zach Copley <zach@status.net>
 * @copyright 2010 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
 * @link      http://status.net/
 */

if (!defined('STATUSNET')) {
    exit(1);
}

class ActivityContext
{
    public $replyToID;
    public $replyToUrl;
    public $location;
    public $attention = array();    // 'uri' => 'type'
    public $conversation;
    public $conversation_url;
    public $scope;

    const THR     = 'http://purl.org/syndication/thread/1.0';
    const GEORSS  = 'http://www.georss.org/georss';
    const OSTATUS = 'http://ostatus.org/schema/1.0';

    const INREPLYTO  = 'in-reply-to';
    const REF        = 'ref';
    const HREF       = 'href';

    // OStatus element names with prefixes
    const OBJECTTYPE = 'ostatus:object-type';   // FIXME: Undocumented!
    const CONVERSATION = 'conversation';

    const POINT     = 'point';

    const MENTIONED    = 'mentioned';

    const ATTN_PUBLIC  = 'http://activityschema.org/collection/public';

    function __construct($element = null)
    {
        if (empty($element)) {
            return;
        }

        $replyToEl = ActivityUtils::child($element, self::INREPLYTO, self::THR);

        if (!empty($replyToEl)) {
            $this->replyToID  = $replyToEl->getAttribute(self::REF);
            $this->replyToUrl = $replyToEl->getAttribute(self::HREF);
        }

        $this->location = $this->getLocation($element);

        foreach ($element->getElementsByTagNameNS(self::OSTATUS, self::CONVERSATION) as $conv) {
            if ($conv->hasAttribute('ref')) {
                $this->conversation = $conv->getAttribute('ref');
                if ($conv->hasAttribute('href')) {
                    $this->conversation_url = $conv->getAttribute('href');
                }
            } else {
                $this->conversation = $conv->textContent;
            }
            if (!empty($this->conversation)) {
                break;
            }
        }
        if (empty($this->conversation)) {
            // fallback to the atom:link rel="ostatus:conversation" element
            $this->conversation = ActivityUtils::getLink($element, 'ostatus:'.self::CONVERSATION);
        }

        // Multiple attention links allowed

        $links = $element->getElementsByTagNameNS(ActivityUtils::ATOM, ActivityUtils::LINK);

        for ($i = 0; $i < $links->length; $i++) {
            $link = $links->item($i);

            $linkRel  = $link->getAttribute(ActivityUtils::REL);
            $linkHref = $link->getAttribute(self::HREF);
            if ($linkRel == self::MENTIONED && $linkHref !== '') {
                $this->attention[$linkHref] = $link->getAttribute(ActivityContext::OBJECTTYPE);
            }
        }
    }

    /**
     * Parse location given as a GeoRSS-simple point, if provided.
     * http://www.georss.org/simple
     *
     * @param feed item $entry
     * @return mixed Location or false
     */
    function getLocation($dom)
    {
        $points = $dom->getElementsByTagNameNS(self::GEORSS, self::POINT);

        for ($i = 0; $i < $points->length; $i++) {
            $point = $points->item($i)->textContent;
            return self::locationFromPoint($point);
        }

        return null;
    }

    // XXX: Move to ActivityUtils or Location?
    static function locationFromPoint($point)
    {
        $point = str_replace(',', ' ', $point); // per spec "treat commas as whitespace"
        $point = preg_replace('/\s+/', ' ', $point);
        $point = trim($point);
        $coords = explode(' ', $point);
        if (count($coords) == 2) {
            list($lat, $lon) = $coords;
            if (is_numeric($lat) && is_numeric($lon)) {
                common_log(LOG_INFO, "Looking up location for $lat $lon from georss point");
                return Location::fromLatLon($lat, $lon);
            }
        }
        common_log(LOG_ERR, "Ignoring bogus georss:point value $point");
        return null;
    }

    /**
     * Returns context (StatusNet stuff) as an array suitable for serializing
     * in JSON. Right now context stuff is an extension to Activity.
     *
     * @return array the context
     */

    function asArray()
    {
        $context = array();

        $context['inReplyTo']    = $this->getInReplyToArray();
        $context['conversation'] = $this->conversation;
        $context['conversation_url'] = $this->conversation_url;

        return array_filter($context);
    }

    /**
     * Returns an array of arrays representing Activity Objects (intended to be
     * serialized in JSON) that represent WHO the Activity is supposed to
     * be received by. This is not really specified but appears in an example
     * of the current spec as an extension. We might want to figure out a JSON
     * serialization for OStatus and use that to express mentions instead.
     *
     * XXX: People's ideas on how to do this are all over the place
     *
     * @return array the array of recipients
     */

    function getToArray()
    {
        $tos = array();

        foreach ($this->attention as $attnUrl => $attnType) {
            $to = array(
                'objectType' => $attnType,  // can be empty
                'id'         => $attnUrl,
            );
            $tos[] = $to;
        }

        return $tos;
    }

    /**
     * Return an array for the notices this notice is a reply to
     * suitable for serializing as JSON note objects.
     *
     * @return array the array of notes
     */

     function getInReplyToArray()
     {
         if (empty($this->replyToID) && empty($this->replyToUrl)) {
             return null;
         }

         $replyToObj = array('objectType' => 'note');

         // XXX: Possibly shorten this to just the numeric ID?
         //      Currently, it's the full URI of the notice.
         if (!empty($this->replyToID)) {
             $replyToObj['id'] = $this->replyToID;
         }
         if (!empty($this->replyToUrl)) {
             $replyToObj['url'] = $this->replyToUrl;
         }

         return $replyToObj;
     }

}