/*
 * Copyright (c) 2011, 2012, 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
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 */

package com.sun.tools.javac.api;

import java.util.Arrays;
import java.util.Collection;

import com.sun.source.util.TaskEvent;
import com.sun.source.util.TaskListener;
import com.sun.tools.javac.code.DeferredCompletionFailureHandler;
import com.sun.tools.javac.code.DeferredCompletionFailureHandler.Handler;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;

A collection of currently registered TaskListeners. Events passed to this TaskListener will be forwarded to all the registered TaskListeners. 
This is NOT part of any supported API.
If you write code that depends on this, you do so at your own risk.
This code and its internal interfaces are subject to change or
deletion without notice.
/**
 * A collection of currently registered {@link TaskListener}s. Events passed to this TaskListener
 * will be forwarded to all the registered TaskListeners.
 *
 * <p><b>This is NOT part of any supported API.
 * If you write code that depends on this, you do so at your own risk.
 * This code and its internal interfaces are subject to change or
 * deletion without notice.</b>
 */
public class MultiTaskListener implements TaskListener {
    
The context key for the MultiTaskListener. /** The context key for the MultiTaskListener. */
    public static final Context.Key<MultiTaskListener> taskListenerKey = new Context.Key<>();

    
Empty array of task listeners /** Empty array of task listeners */
    private static final TaskListener[] EMPTY_LISTENERS = new TaskListener[0];

    private final DeferredCompletionFailureHandler dcfh;

    
Get the MultiTaskListener instance for this context. /** Get the MultiTaskListener instance for this context. */
    public static MultiTaskListener instance(Context context) {
        MultiTaskListener instance = context.get(taskListenerKey);
        if (instance == null)
            instance = new MultiTaskListener(context);
        return instance;
    }

    protected MultiTaskListener(Context context) {
        context.put(taskListenerKey, this);
        ccw = ClientCodeWrapper.instance(context);
        dcfh = DeferredCompletionFailureHandler.instance(context);
    }

    
The current set of registered listeners.
This is a mutable reference to an immutable array.
/**
     * The current set of registered listeners.
     * This is a mutable reference to an immutable array.
     */
    TaskListener[] listeners = EMPTY_LISTENERS;

    ClientCodeWrapper ccw;

    public Collection<TaskListener> getTaskListeners() {
        return Arrays.asList(listeners);
    }

    public boolean isEmpty() {
        return listeners == EMPTY_LISTENERS;
    }

    public void add(TaskListener listener) {
        for (TaskListener l: listeners) {
            if (ccw.unwrap(l) == listener)
                throw new IllegalStateException();
        }
        listeners = Arrays.copyOf(listeners, listeners.length + 1);
        listeners[listeners.length - 1] = ccw.wrap(listener);
    }

    public void remove(TaskListener listener) {
        for (int i = 0; i < listeners.length; i++) {
            if (ccw.unwrap(listeners[i]) == listener) {
                if (listeners.length == 1) {
                    listeners = EMPTY_LISTENERS;
                } else {
                    TaskListener[] newListeners = new TaskListener[listeners.length - 1];
                    System.arraycopy(listeners, 0, newListeners, 0, i);
                    System.arraycopy(listeners, i + 1, newListeners, i, newListeners.length - i);
                    listeners = newListeners;
                }
                break;
            }
        }
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public void started(TaskEvent e) {
        Handler prevDeferredHandler = dcfh.setHandler(dcfh.userCodeHandler);
        try {
            // guard against listeners being updated by a listener
            TaskListener[] ll = this.listeners;
            for (TaskListener l: ll)
                l.started(e);
        } finally {
            dcfh.setHandler(prevDeferredHandler);
        }
    }

    @Override @DefinedBy(Api.COMPILER_TREE)
    public void finished(TaskEvent e) {
        Handler prevDeferredHandler = dcfh.setHandler(dcfh.userCodeHandler);
        try {
            // guard against listeners being updated by a listener
            TaskListener[] ll = this.listeners;
            for (TaskListener l: ll)
                l.finished(e);
        } finally {
            dcfh.setHandler(prevDeferredHandler);
        }
    }

    @Override
    public String toString() {
        return Arrays.toString(listeners);
    }

    public void clear() {
        listeners = EMPTY_LISTENERS;
    }
}