/**

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

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 * Copyright 2013-2014 Oracle and/or its affiliates. All rights reserved.

 *

 * Oracle and Java are registered trademarks of Oracle and/or its affiliates.

 * Other names may be trademarks of their respective owners.

 *

 * The contents of this file are subject to the terms of either the GNU

 * General Public License Version 2 only ("GPL") or the Common

 * Development and Distribution License("CDDL") (collectively, the

 * "License"). You may not use this file except in compliance with the

 * License. You can obtain a copy of the License at

 * http://www.netbeans.org/cddl-gplv2.html

 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

 * specific language governing permissions and limitations under the

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 * Notice in each file and include the License file at

 * nbbuild/licenses/CDDL-GPL-2-CP.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the GPL Version 2 section of the License file that

 * accompanied this code. If applicable, add the following below the

 * License Header, with the fields enclosed by brackets [] replaced by

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 *

 * The Original Software is NetBeans. The Initial Developer of the Original

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 *

 * If you wish your version of this file to be governed by only the CDDL

 * or only the GPL Version 2, indicate your decision by adding

 * "[Contributor] elects to include this software in this distribution

 * under the [CDDL or GPL Version 2] license." If you do not indicate a

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 * However, if you add GPL Version 2 code and therefore, elected the GPL

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 */

package org.netbeans.html.boot.impl;

import java.io.Closeable;

import java.io.Flushable;

import java.io.IOException;

import java.util.logging.Logger;

import org.apidesign.html.boot.spi.Fn;

/**

 *

 * @author Jaroslav Tulach

 */

public final class FnContext implements Closeable {

    private static final Logger LOG = Logger.getLogger(FnContext.class.getName());

    private static final FnContext DUMMY;

    static {

        DUMMY = new FnContext(null, null);

        DUMMY.prev = DUMMY;

    }

    private Object prev;

    private final Fn.Presenter current;

    private FnContext(Fn.Presenter prevP, Fn.Presenter newP) {

        this.current = newP;

        this.prev = prevP;

    }

    @Override

    public void close() throws IOException {

        if (prev != this) {

            currentPresenter((Fn.Presenter)prev);

            prev = this;

            if (current instanceof Flushable) {

                ((Flushable)current).flush();

            }

        }

    }

/*

    @Override

    protected void finalize() throws Throwable {

        if (prev != null) {

            LOG.warning("Unclosed context!");

        }

    }

*/

    public static Closeable activate(Fn.Presenter newP) {

        final Fn.Presenter oldP = currentPresenter(newP);

        if (oldP == newP) {

            return DUMMY;

        }

        return new FnContext(oldP, newP);

    }

    private static final ThreadLocal<Fn.Presenter> CURRENT = new ThreadLocal<Fn.Presenter>();

    public static Fn.Presenter currentPresenter(Fn.Presenter p) {

        Fn.Presenter prev = CURRENT.get();

        CURRENT.set(p);

        return prev;

    }

    public static Fn.Presenter currentPresenter(boolean fail) {

        Fn.Presenter p = CURRENT.get();

        if (p == null && fail) {

            throw new IllegalStateException("No current WebView context around!");

        }

        return p;

    }

}