/*
 * 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.cocoon.components.modules.input;

import java.util.Iterator;
import java.util.Map;
import java.util.Vector;

import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.cocoon.environment.ObjectModelHelper;

/**
 * BaseLinkModule returns a relative link (<code>../</code>,
 * <code>../../</code> etc) to the base of the current request or sitemap URI.  For
 * instance, if called within a <map:match pattern="a/b/c.xsp"> pipeline,
 * <code>{baselink:SitemapBaseLink}</code> would evaluate to <code>../../</code>.
 * 
 * based on {@link RequestURIModule}
 *
 * @author <a href="mailto:tk-cocoon@datas-world.de">Torsten Knodt</a>
 */
public class BaseLinkModule extends AbstractInputModule implements ThreadSafe {

    final static Vector returnNames = new Vector() {
        {
            add("RequestBaseLink");
            add("SitemapBaseLink");
        }
    };

    public Object getAttribute(
        final String name,
        final Configuration modeConf,
        final Map objectModel)
        throws ConfigurationException {

        String uri;
        if (name.equals("SitemapBaseLink"))
            uri = ObjectModelHelper.getRequest(objectModel).getSitemapURI();
        else if (name.equals("RequestBaseLink"))
            uri = ObjectModelHelper.getRequest(objectModel).getRequestURI();
        else
            uri = "";

        if (uri.startsWith("/")) {
            uri = uri.substring(1);
        }

        StringBuffer result = new StringBuffer(uri.length());

        int nextIndex = 0;
        while ((nextIndex = uri.indexOf('/', nextIndex) + 1) > 0) {
            result.append("../");
        }

        if (getLogger().isDebugEnabled())
            getLogger().debug("Returns " + result + " for uri " + uri + " and attribute " + name);

        return result.toString();
    }

    public Iterator getAttributeNames(final Configuration modeConf, final Map objectModel)
        throws ConfigurationException {

        return RequestURIModule.returnNames.iterator();
    }

    public Object[] getAttributeValues(
        final String name,
        final Configuration modeConf,
        final Map objectModel)
        throws ConfigurationException {

        Object result = new Object[1];
        result = getAttribute(name, modeConf, objectModel);
        return (result == null? null : new Object[]{result});        
    }

}