User:Jack Phoenix/MetaTag/MetaTag.php

<?php
/**
 * MetaTag.php - A MediaWiki tag extension for adding <meta> tags to a page.
 * @author Peter Georgeson
 * @version 0.2
 * @copyright Copyright (C) 2007 Peter Georgeson
 * @license The MIT License - http://www.opensource.org/licenses/mit-license.php
 * -----------------------------------------------------------------------
 * Description:
 *       This is a MediaWiki extension which adds support for injecting <meta> keyword tags
 *       into the page header.
 *       Heavily based on Jim R. Wilson's meta keywords extension
 * Requirements:
 *       MediaWiki 1.17 or higher
 *       5.x or higher
 * Installation:
 *       1. Drop this script (MetaTag.php) and the i18n file in $IP/extensions/MetaTag
 *               Note: $IP is your MediaWiki install dir.
 *       2. Enable the extension by adding this line to your LocalSettings.php:
 *               require_once($IP . 'extensions/MetaTag/MetaTag.php');
 * Usage:
 *       Once installed, you may utilize MetaTag by adding the <meta> tag to articles:
 *               <meta name="keywords" content="example, data" />
 *       Change the title of the page with the command:
 *               <meta name="title" content="new title"/>
 * Version Notes:
 *	 version 0.2:
 *               Modernized not to break newer MediaWikis.
 *	 version 0.1:
 *               Initial release.
 * -----------------------------------------------------------------------
 * Copyright (c) 2008 Peter Georgeson
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 * -----------------------------------------------------------------------
 */

# Confirm MW environment
if ( !defined( 'MEDIAWIKI' ) ) {
	die( 'This is not a valid entry point to MediaWiki.' );
}

// Extension credits that will show up on Special:Version
$wgExtensionCredits['parserhook'][] = array(
	'name' => 'MetaTag',
	'version' => '0.2',
	'author' => array( 'Jim Wilson', 'Peter Georgeson' ),
	'url' => 'http://jimbojw.com/wiki/index.php?title=MetaKeywordsTag',
	'description' => 'Tag to inject meta tags into page header',
);

// Set up i18n
$wgExtensionMessagesFiles['MetaTag'] = dirname( __FILE__ ) . '/MetaTag.i18n.php';

// Register the <meta> tag with MediaWiki's Parser
$wgHooks['ParserFirstCallInit'][] = 'setupMetaTagParserHook';

/**
 * Register the <meta> tag with MediaWiki's Parser
 */
function setupMetaTagParserHook( &$parser ) {
	$parser->setHook( 'meta', 'renderMetaTag' );
	return true;
}

/**
 * Renders the <meta> tag.
 * @param String $text Incomming text - should always be null or empty (passed by value).
 * @param Array $params Attributes specified for tag - must contain 'content' (passed by value).
 * @param Parser $parser Reference to currently running parser (passed by reference).
 * @return String Always empty.
 */
function renderMetaTag( $text, $params = array() ) {
	return encodeTag( $params['name'], $params['content'] );
}

function encodeTag( $name, $content ) {
	# Short-circuit with error message if content is not specified.
	if ( !isset( $content ) ) {
		return
			'<div class="errorbox">' .
			wfMessage( 'metatag-missing-content' )->text() .
			'</div>';
	}
	if ( !isset( $name ) ) {
		return
			'<div class="errorbox">' .
			wfMessage( 'metatag-missing-name' )->text() .
			'</div>';
	}

	# Return encoded content
	return '<!-- META_' . $name . ' ' . base64_encode( $content ) . ' -->';
}

# Attach post-parser hook to extract metadata and alter headers
$wgHooks['OutputPageBeforeHTML'][] = 'insertMetaTags';

/**
 * Adds the <meta> keywords to document head.
 * Usage: $wgHooks['OutputPageBeforeHTML'][] = 'insertMetaKeywords';
 * @param OutputPage $out Handle to an OutputPage object - presumably $wgOut (passed by reference).
 * @param String $text Output text.
 * @return Boolean Always true to allow other extensions to continue processing.
 */
function insertMetaTags( $out, $text ) {
	# Extract meta keywords
	if ( preg_match_all(
		'/<!-- META_([a-zA-Z]+) ([0-9a-zA-Z\\-\\+\\/]+=*) -->/m',
		$text,
		$matches ) === false
	)
	{
		return true;
	}
	$name = $matches[1];
	$data = $matches[2];

	# Merge keyword data into OutputPage as meta tags
	for ( $i = 0; $i < sizeof( $name ); $i++ ) {
		wfSuppressWarnings();
		$content = base64_decode( $data[$i] );
		wfRestoreWarnings();
		if ( $content ) {
			if ( $name[$i] == 'title' ) {
				$out->setHTMLTitle( $content );
			} else {
				$out->addMeta( $name[$i], $content );
			}
		}
	}
	return true;
}