wikimedia/mediawiki-core

<?php

/**
 * Copyright (C) 2011-2020 Wikimedia Foundation and others.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

namespace MediaWiki\Rest\Handler;

use ApiOpenSearch;
use MediaWiki\Config\Config;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\MainConfigNames;
use MediaWiki\MainConfigSchema;
use MediaWiki\Rest\Handler;
use MediaWiki\Rest\Response;
use MediaWiki\Rest\StringStream;
use MediaWiki\SpecialPage\SpecialPage;
use MediaWiki\Utils\UrlUtils;
use MediaWiki\Xml\Xml;
use Wikimedia\Http\HttpAcceptParser;

/**
 * Handler for generating an OpenSearch description document.
 * In a nutshell, this tells browsers how and where
 * to submit search queries to get a search results page back,
 * as well as how to get typeahead suggestions (see ApiOpenSearch).
 *
 * This class handles the following routes:
 * - /v1/search
 *
 * @see https://github.com/dewitt/opensearch
 * @see https://www.opensearch.org
 */
class OpenSearchDescriptionHandler extends Handler {

    private UrlUtils $urlUtils;

    /** @see MainConfigSchema::Favicon */
    private string $favicon;

    /** @see MainConfigSchema::OpenSearchTemplates */
    private array $templates;

    public function __construct( Config $config, UrlUtils $urlUtils ) {
        $this->favicon = $config->get( MainConfigNames::Favicon );
        $this->templates = $config->get( MainConfigNames::OpenSearchTemplates );
        $this->urlUtils = $urlUtils;
    }

    public function execute(): Response {
        $ctype = $this->getContentType();

        $response = $this->getResponseFactory()->create();
        $response->setHeader( 'Content-type', $ctype );

        // Set an Expires header so that CDN can cache it for a short time
        // Short enough so that the sysadmin barely notices when $wgSitename is changed
        $expiryTime = 600; # 10 minutes
        $response->setHeader( 'Expires', gmdate( 'D, d M Y H:i:s', time() + $expiryTime ) . ' GMT' );
        $response->setHeader( 'Cache-control', 'max-age=600' );

        $body = new StringStream();

        $body->write( '<?xml version="1.0"?>' );
        $body->write( Xml::openElement( 'OpenSearchDescription',
            [
                'xmlns' => 'http://a9.com/-/spec/opensearch/1.1/',
                'xmlns:moz' => 'http://www.mozilla.org/2006/browser/search/' ] ) );

        // The spec says the ShortName must be no longer than 16 characters,
        // but 16 is *realllly* short. In practice, browsers don't appear to care
        // when we give them a longer string, so we're no longer attempting to trim.
        //
        // Note: ShortName and the <link title=""> need to match; they are used as
        // a key for identifying if the search engine has been added already, *and*
        // as the display name presented to the end-user.
        //
        // Behavior seems about the same between Firefox and IE 7/8 here.
        // 'Description' doesn't appear to be used by either.
        $fullName = wfMessage( 'opensearch-desc' )->inContentLanguage()->text();
        $body->write( Xml::element( 'ShortName', null, $fullName ) );
        $body->write( Xml::element( 'Description', null, $fullName ) );

        // By default we'll use the site favicon.
        // Double-check if IE supports this properly?
        $body->write( Xml::element( 'Image',
            [
                'height' => 16,
                'width' => 16,
                'type' => 'image/x-icon'
            ],
            (string)$this->urlUtils->expand( $this->favicon, PROTO_CURRENT )
        ) );

        $urls = [];

        // General search template. Given an input term, this should bring up
        // search results or a specific found page.
        // At least Firefox and IE 7 support this.
        $searchPage = SpecialPage::getTitleFor( 'Search' );
        $urls[] = [
            'type' => 'text/html',
            'method' => 'get',
            'template' => $searchPage->getCanonicalURL( 'search={searchTerms}' ) ];

        // TODO: add v1/search/ endpoints?

        foreach ( $this->templates as $type => $template ) {
            if ( !$template ) {
                $template = ApiOpenSearch::getOpenSearchTemplate( $type );
            }

            if ( $template ) {
                $urls[] = [
                    'type' => $type,
                    'method' => 'get',
                    'template' => $template,
                ];
            }
        }

        // Allow hooks to override the suggestion URL settings in a more
        // general way than overriding the whole search engine...
        ( new HookRunner( $this->getHookContainer() ) )->onOpenSearchUrls( $urls );

        foreach ( $urls as $attribs ) {
            $body->write( Xml::element( 'Url', $attribs ) );
        }

        // And for good measure, add a link to the straight search form.
        // This is a custom format extension for Firefox, which otherwise
        // sends you to the domain root if you hit "enter" with an empty
        // search box.
        $body->write( Xml::element( 'moz:SearchForm', null,
            $searchPage->getCanonicalURL() ) );

        $body->write( Xml::closeElement( 'OpenSearchDescription' ) );

        $response->setBody( $body );
        return $response;
    }

    /**
     * Returns the content-type to use for the response.
     * Will be either 'application/xml' or 'application/opensearchdescription+xml',
     * depending on the client's preference.
     *
     * @return string
     */
    private function getContentType(): string {
        $params = $this->getValidatedParams();
        if ( $params['ctype'] == 'application/xml' ) {
            // Makes testing tweaks about a billion times easier
            return 'application/xml';
        }

        $acceptHeader = $this->getRequest()->getHeader( 'accept' );

        if ( $acceptHeader ) {
            $parser = new HttpAcceptParser();
            $acceptableTypes = $parser->parseAccept( $acceptHeader[0] );

            foreach ( $acceptableTypes as $acc ) {
                if ( $acc['type'] === 'application/xml' ) {
                    return 'application/xml';
                }
            }
        }

        return 'application/opensearchdescription+xml';
    }

    public function getParamSettings() {
        return [
            'ctype' => [
                self::PARAM_SOURCE => 'query',
            ]
        ];
    }

}