MetaRefreshUrlStringTransformer.java

/*
 *  This file is part of the Wayback archival access software
 *   (http://archive-access.sourceforge.net/projects/wayback/).
 *
 *  Licensed to the Internet Archive (IA) by one or more individual 
 *  contributors. 
 *
 *  The IA licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.archive.wayback.replay.html.transformer;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.archive.wayback.replay.html.ReplayParseContext;

/**
 * Translates URL found in META-REFRESH's <code>CONTENT</code> attribute.
 * <p>
 * Extracts URL part in <code>CONTENT</code> attribute value, and translates it.
 * </p>
 * <p>Possible Refactoring:
 * There's no strong reason this class should extend {@link URLStringTransformer}.
 * Since <code>javascript:</code> URI in META-REFRESH is rejected by most browsers,
 * <code>transform</code> method could simply call {@link ReplayParseContext#contextualizeUrl(String)}
 * rather than <code>super.transform</code>.  As META-REFRESH is found only in HTML
 * document, there's no need for <code>flags</code> member either.
 * </p>
 *
 * @author brad
 *
 */
public class MetaRefreshUrlStringTransformer extends URLStringTransformer {

	private final static Pattern refreshURLPattern = Pattern.compile(
			"^[\\d.]+\\s*;\\s*url\\s*=\\s*(.+?)\\s*$", Pattern.CASE_INSENSITIVE
					| Pattern.MULTILINE);

	/*
	 * (non-Javadoc)
	 *
	 * @see
	 * org.archive.wayback.replay.html.StringTransformer#transform(org.archive
	 * .wayback.replay.html.ReplayParseContext, java.lang.String)
	 */
	public String transform(ReplayParseContext context, String input) {
		// Ex. <META HTTP-EQUIV="Refresh" CONTENT="0; URL=/ics/default.asp">
		// input receives the value of the "CONTENT" attribute.
		// So, we need to search for the "URL=", take everything to the right of
		// that, trim it, contextualize it, and return that.
		Matcher m = refreshURLPattern.matcher(input);
		if (m.matches()) {
			if (m.groupCount() == 1) {
				String url = m.group(1);
				String replayUrl = context.contextualizeUrl(url);
				if (replayUrl != url) {
					input = input.substring(0, m.start(1)) + replayUrl +
							input.substring(m.end(1));
				}
			}
		}
		return input;
	}

}