<?php
/**
 * The web entry point for generating an OpenSearch description document.
 *
 * See <http://www.opensearch.org/> for the specification of the OpenSearch
 * "description" document. In a nut shell, this tells browsers how and where
 * to submit submit search queries to get a search results page back,
 * as well as how to get typeahead suggestions (see ApiOpenSearch).
 *
 * 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.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup entrypoint
 */

use MediaWiki\HookContainer\HookRunner;
use MediaWiki\MediaWikiServices;
use MediaWiki\SpecialPage\SpecialPage;

// This endpoint is supposed to be independent of request cookies and other
// details of the session. Enforce this constraint with respect to session use.
define( 'MW_NO_SESSION', 1 );

define( 'MW_ENTRY_POINT', 'opensearch_desc' );

require_once __DIR__ . '/includes/WebStart.php';

wfOpenSearchDescMain();

function wfOpenSearchDescMain() {
	global $wgRequest, $wgFavicon, $wgOpenSearchTemplates;

	if ( $wgRequest->getVal( 'ctype' ) == 'application/xml' ) {
		// Makes testing tweaks about a billion times easier
		$ctype = 'application/xml';
	} else {
		$ctype = 'application/opensearchdescription+xml';
	}

	$response = $wgRequest->response();
	$response->header( "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->header( 'Expires: ' . gmdate( 'D, d M Y H:i:s', time() + $expiryTime ) . ' GMT' );
	$response->header( 'Cache-control: max-age=600' );

	print '<?xml version="1.0"?>';
	print 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();
	print Xml::element( 'ShortName', null, $fullName );
	print Xml::element( 'Description', null, $fullName );

	$services = MediaWikiServices::getInstance();

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

	foreach ( $wgOpenSearchTemplates 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( $services->getHookContainer() ) )->onOpenSearchUrls( $urls );

	foreach ( $urls as $attribs ) {
		print 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.
	print Xml::element( 'moz:SearchForm', null,
		$searchPage->getCanonicalURL() );

	print '</OpenSearchDescription>';
}