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This OSGi bundle wraps org.restlet, and com.noelios.restlet ${pkgVersion} jar files.
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/**
 * Copyright 2005-2008 Noelios Technologies.
 * 
 * The contents of this file are subject to the terms of the following open
 * source licenses: LGPL 3.0 or LGPL 2.1 or CDDL 1.0 (the "Licenses"). You can
 * select the license that you prefer but you may not use this file except in
 * compliance with one of these Licenses.
 * 
 * You can obtain a copy of the LGPL 3.0 license at
 * http://www.gnu.org/licenses/lgpl-3.0.html
 * 
 * You can obtain a copy of the LGPL 2.1 license at
 * http://www.gnu.org/licenses/lgpl-2.1.html
 * 
 * You can obtain a copy of the CDDL 1.0 license at
 * http://www.sun.com/cddl/cddl.html
 * 
 * See the Licenses for the specific language governing permissions and
 * limitations under the Licenses.
 * 
 * Alternatively, you can obtain a royaltee free commercial license with less
 * limitations, transferable or non-transferable, directly at
 * http://www.noelios.com/products/restlet-engine
 * 
 * Restlet is a registered trademark of Noelios Technologies.
 */

package com.noelios.restlet;

import java.util.logging.Level;

import org.restlet.Context;
import org.restlet.Filter;
import org.restlet.Restlet;
import org.restlet.data.Request;
import org.restlet.data.Response;
import org.restlet.data.Status;
import org.restlet.service.LogService;
import org.restlet.util.Helper;

/**
 * Chain helper serving as base class for Application and Component helpers.
 * 
 * @author Jerome Louvel
 */
public abstract class ChainHelper extends Helper {
    /** The first Restlet. */
    private volatile Restlet first;

    /** The last Filter. */
    private volatile Filter last;

    /**
     * Constructor.
     * 
     * @param helped
     *            The helped Restlet.
     */
    public ChainHelper(T helped) {
        super(helped);
        this.first = null;
    }

    /**
     * Adds a new filter to the chain.
     * 
     * @param filter
     *            The filter to add.
     */
    protected synchronized void addFilter(Filter filter) {
        if (getLast() != null) {
            getLast().setNext(filter);
            setLast(filter);
        } else {
            setFirst(filter);
            setLast(filter);
        }
    }

    /**
     * Clears the chain. Sets the first and last filters to null.
     */
    public void clear() {
        setFirst(null);
        setNext(null);
    }

    /**
     * Creates a new log filter. Allows overriding.
     * 
     * @param context
     *            The context.
     * @param logService
     *            The log service descriptor.
     * @return The new log filter.
     */
    protected Filter createLogFilter(Context context, LogService logService) {
        return new LogFilter(context, logService);
    }

    /**
     * Returns the first Restlet.
     * 
     * @return the first Restlet.
     */
    protected Restlet getFirst() {
        return this.first;
    }

    /**
     * Returns the last Filter.
     * 
     * @return the last Filter.
     */
    protected Filter getLast() {
        return this.last;
    }

    @Override
    public void handle(Request request, Response response) {
        super.handle(request, response);

        if (getFirst() != null) {
            getFirst().handle(request, response);
        } else {
            response.setStatus(Status.SERVER_ERROR_INTERNAL);
            getHelped()
                    .getLogger()
                    .log(
                            Level.SEVERE,
                            "The "
                                    + getHelped().getClass().getName()
                                    + " class has no Restlet defined to process calls. Maybe it wasn't properly started.");
        }
    }

    /**
     * Sets the first Restlet.
     * 
     * @param first
     *            The first Restlet.
     */
    protected void setFirst(Restlet first) {
        this.first = first;
    }

    /**
     * Sets the last Filter.
     * 
     * @param last
     *            The last Filter.
     */
    protected void setLast(Filter last) {
        this.last = last;
    }

    /**
     * Sets the next Restlet after the chain.
     * 
     * @param next
     *            The Restlet to process after the chain.
     */
    protected synchronized void setNext(Restlet next) {
        if (getFirst() == null) {
            setFirst(next);
        } else {
            getLast().setNext(next);
        }
    }

}