/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF 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.apache.lenya.cms.linking;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.regex.Pattern;

import org.apache.lenya.util.Assert;

public class RelativeToAbsoluteLinkRewriter implements LinkRewriter {

    private String sourceUri;
    
    protected static final Pattern PROTOCOL_REGEX = Pattern.compile("[A-Za-z0-9\\-]+\\:");
    
    public RelativeToAbsoluteLinkRewriter(String sourceUri) {
        Assert.notNull("source URI", sourceUri);
        this.sourceUri = sourceUri;
    }

    public boolean matches(String url) {
        Assert.notNull("url", url);
        return !url.startsWith("/") && !url.startsWith("#") && !PROTOCOL_REGEX.matcher(url).find();
    }

    public String rewrite(final String url) {
        try {
            final int lastSlashIndex = this.sourceUri.lastIndexOf('/');
            final String prefix = lastSlashIndex < 0 ? "" : this.sourceUri.substring(0,
                    lastSlashIndex + 1);
            final String newUrl = prefix + url;
            final String normalizedUrl = new URI(newUrl).normalize().toString();
            return normalizedUrl;
        } catch (URISyntaxException e) {
            throw new RuntimeException(e);
        }
    }

}