/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

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

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

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

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.jshell.execution;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.concurrent.atomic.AtomicReference;

/**

 * An implementation of {@link jdk.jshell.spi.ExecutionControl} which executes

 * in the same JVM as the JShell-core.

 *

 * @author Grigory Ptashko

 */

public class LocalExecutionControl extends DirectExecutionControl {

    private final Object STOP_LOCK = new Object();

    private boolean userCodeRunning = false;

    private ThreadGroup execThreadGroup;

    /**

     * Creates an instance, delegating loader operations to the specified

     * delegate.

     *

     * @param loaderDelegate the delegate to handle loading classes

     */

    public LocalExecutionControl(LoaderDelegate loaderDelegate) {

        super(loaderDelegate);

    }

    /**

     * Create an instance using the default class loading.

     */

    public LocalExecutionControl() {

    }

    @Override

    protected String invoke(Method doitMethod) throws Exception {

        execThreadGroup = new ThreadGroup("JShell process local execution");

        AtomicReference<InvocationTargetException> iteEx = new AtomicReference<>();

        AtomicReference<IllegalAccessException> iaeEx = new AtomicReference<>();

        AtomicReference<NoSuchMethodException> nmeEx = new AtomicReference<>();

        AtomicReference<Boolean> stopped = new AtomicReference<>(false);

        Thread.setDefaultUncaughtExceptionHandler((t, e) -> {

            if (e instanceof InvocationTargetException) {

                if (e.getCause() instanceof ThreadDeath) {

                    stopped.set(true);

                } else {

                    iteEx.set((InvocationTargetException) e);

                }

            } else if (e instanceof IllegalAccessException) {

                iaeEx.set((IllegalAccessException) e);

            } else if (e instanceof NoSuchMethodException) {

                nmeEx.set((NoSuchMethodException) e);

            } else if (e instanceof ThreadDeath) {

                stopped.set(true);

            }

        });

        final Object[] res = new Object[1];

        Thread snippetThread = new Thread(execThreadGroup, () -> {

            try {

                res[0] = doitMethod.invoke(null, new Object[0]);

            } catch (InvocationTargetException e) {

                if (e.getCause() instanceof ThreadDeath) {

                    stopped.set(true);

                } else {

                    iteEx.set(e);

                }

            } catch (IllegalAccessException e) {

                iaeEx.set(e);

            } catch (ThreadDeath e) {

                stopped.set(true);

            }

        });

        snippetThread.start();

        Thread[] threadList = new Thread[execThreadGroup.activeCount()];

        execThreadGroup.enumerate(threadList);

        for (Thread thread : threadList) {

            if (thread != null) {

                thread.join();

            }

        }

        if (stopped.get()) {

            throw new StoppedException();

        }

        if (iteEx.get() != null) {

            throw iteEx.get();

        } else if (nmeEx.get() != null) {

            throw nmeEx.get();

        } else if (iaeEx.get() != null) {

            throw iaeEx.get();

        }

        return valueString(res[0]);

    }

    @Override

    @SuppressWarnings("deprecation")

    public void stop() throws EngineTerminationException, InternalException {

        synchronized (STOP_LOCK) {

            if (!userCodeRunning) {

                return;

            }

            if (execThreadGroup == null) {

                throw new InternalException("Process-local code snippets thread group is null. Aborting stop.");

            }

            execThreadGroup.stop();

        }

    }

    @Override

    protected void clientCodeEnter() {

        synchronized (STOP_LOCK) {

            userCodeRunning = true;

        }

    }

    @Override

    protected void clientCodeLeave() {

        synchronized (STOP_LOCK) {

            userCodeRunning = false;

        }

    }

}