gnu-social/lib/activity.php

<?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 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/';

    public $actor;   // an ActivityObject
    public $verb;    // a string (the URL)
    public $object;  // an ActivityObject
    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

    /**
     * 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(
                _("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, $feed);
        } else {
            throw new Exception("Unknown DOM element: {$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
        }

        $objectEl = $this->_child($entry, self::OBJECT);

        if (!empty($objectEl)) {
            $this->object = new ActivityObject($objectEl);
        } else {
            $this->object = new ActivityObject($entry);
        }

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

        if (!empty($actorEl)) {

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

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

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

        } else if ($authorEl = $this->_child($entry, self::AUTHOR, self::ATOM)) {

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

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

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

        $this->summary = ActivityUtils::childContent($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');
        }
    }

    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);
        }

        $authorEl = $this->_child($item, self::AUTHOR, self::RSS);

        if (!empty($authorEl)) {
            $this->actor = ActivityObject::fromRssAuthor($authorEl);
        } else {
            $dcCreatorEl = $this->_child($item, self::CREATOR, self::DC);
            if (!empty($dcCreatorEl)) {
                $this->actor = ActivityObject::fromDcCreator($dcCreatorEl);
            } else if (!empty($channel)) {
                $this->actor = ActivityObject::fromRssChannel($channel);
            }
        }

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

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

        if (!empty($contentEl)) {
            $this->content = htmlspecialchars_decode($contentEl->textContent, ENT_QUOTES);
        } else {
            $descriptionEl = ActivityUtils::child($item, self::DESCRIPTION, self::RSS);
            if (!empty($descriptionEl)) {
                $this->content = htmlspecialchars_decode($descriptionEl->textContent, ENT_QUOTES);
            }
        }

        $this->link = ActivityUtils::childContent($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;
            }
        }

        $this->object  = new ActivityObject($item);
        $this->context = new ActivityContext($item);
    }

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

    function toAtomEntry()
    {
        return null;
    }

    function asString($namespace=false)
    {
        $xs = new XMLStringer(true);

        if ($namespace) {
            $attrs = array('xmlns' => 'http://www.w3.org/2005/Atom',
                           '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');
        } else {
            $attrs = array();
        }

        $xs->elementStart('entry', $attrs);

        $xs->element('id', null, $this->id);
        $xs->element('title', null, $this->title);
        $xs->element('published', null, common_date_iso8601($this->time));
        $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'),
                         $this->link);
        }

        // XXX: add context

        $xs->elementStart('author');
        $xs->element('uri', array(), $this->actor->id);
        if ($this->actor->title) {
            $xs->element('name', array(), $this->actor->title);
        }
        $xs->elementEnd('author');
        $xs->raw($this->actor->asString('activity:actor'));

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

        if ($this->object) {
            $xs->raw($this->object->asString());
        }

        if ($this->target) {
            $xs->raw($this->target->asString('activity:target'));
        }

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

        $xs->elementEnd('entry');

        return $xs->getString();
    }

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

class AtomCategory
{
    public $term;
    public $scheme;
    public $label;

    function __construct($element=null)
    {
        if ($element && $element->attributes) {
            $this->term = $this->extract($element, 'term');
            $this->scheme = $this->extract($element, 'scheme');
            $this->label = $this->extract($element, 'label');
        }
    }

    protected function extract($element, $attrib)
    {
        $node = $element->attributes->getNamedItemNS(Activity::ATOM, $attrib);
        if ($node) {
            return trim($node->textContent);
        }
        $node = $element->attributes->getNamedItem($attrib);
        if ($node) {
            return trim($node->textContent);
        }
        return null;
    }

    function asString()
    {
        $attribs = array();
        if ($this->term !== null) {
            $attribs['term'] = $this->term;
        }
        if ($this->scheme !== null) {
            $attribs['scheme'] = $this->scheme;
        }
        if ($this->label !== null) {
            $attribs['label'] = $this->label;
        }
        $xs = new XMLStringer();
        $xs->element('category', $attribs);
        return $xs->asString();
    }
}