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// 
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// 
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
// 
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// 
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
// 
package org.eclipse.jetty.server.handler;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.HandlerContainer;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.util.annotation.ManagedAttribute;
import org.eclipse.jetty.util.annotation.ManagedObject;
import org.eclipse.jetty.util.component.LifeCycle;

/**
 *  A HandlerWrapper acts as a {@link Handler} but delegates the {@link Handler#handle handle} method and
 *  {@link LifeCycle life cycle} events to a delegate. This is primarily used to implement the Decorator pattern.
 *
 * @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
 */
@ManagedObject("Handler wrapping another Handler")
@Deprecated(since = "2021-05-27")
public class HandlerWrapper extends AbstractHandlerContainer {

    protected Handler _handler;

    /**
     */
    public HandlerWrapper() {
    }

    /**
     * @return Returns the handlers.
     */
    @ManagedAttribute(value = "Wrapped Handler", readonly = true)
    public Handler getHandler() {
        return _handler;
    }

    /**
     * @return Returns the handlers.
     */
    @Override
    public Handler[] getHandlers() {
        if (_handler == null)
            return new Handler[0];
        return new Handler[] { _handler };
    }

    /**
     * @param handler Set the {@link Handler} which should be wrapped.
     */
    public void setHandler(Handler handler) {
        if (isStarted())
            throw new IllegalStateException(STARTED);
        // check for loops
        if (handler == this || (handler instanceof HandlerContainer && Arrays.asList(((HandlerContainer) handler).getChildHandlers()).contains(this)))
            throw new IllegalStateException("setHandler loop");
        if (handler != null)
            handler.setServer(getServer());
        Handler old = _handler;
        _handler = handler;
        updateBean(old, _handler, true);
    }

    /**
     * Replace the current handler with another HandlerWrapper
     * linked to the current handler.
     * 
     * This is equivalent to:
     * 
     *   wrapper.setHandler(getHandler());
     *   setHandler(wrapper);
     * 
     *
     * @param wrapper the wrapper to insert
     */
    public void insertHandler(HandlerWrapper wrapper) {
        if (wrapper == null)
            throw new IllegalArgumentException();
        HandlerWrapper tail = wrapper;
        while (tail.getHandler() instanceof HandlerWrapper) {
            tail = (HandlerWrapper) tail.getHandler();
        }
        if (tail.getHandler() != null)
            throw new IllegalArgumentException("bad tail of inserted wrapper chain");
        Handler next = getHandler();
        setHandler(wrapper);
        tail.setHandler(next);
    }

    @Override
    public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
        Handler handler = _handler;
        if (handler != null)
            handler.handle(target, baseRequest, request, response);
    }

    @Override
    protected void expandChildren(List list, Class byClass) {
        expandHandler(_handler, list, byClass);
    }

    @Override
    public void destroy() {
        if (!isStopped())
            throw new IllegalStateException("!STOPPED");
        Handler child = getHandler();
        if (child != null) {
            setHandler(null);
            child.destroy();
        }
        super.destroy();
    }
}