/*

 * Copyright (c) 2016, 2018, 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.jfr.consumer;

import java.util.ArrayList;

import java.util.List;

/**

 * Holds mapping between a set of keys and their corresponding object.

 *

 * If the type is a known type, i.e. {@link RecordedThread}, an

 * {@link ObjectFactory} can be supplied which will instantiate a typed object.

 */

final class ConstantMap {

    private final static class Reference {

        private final long key;

        private final ConstantMap pool;

        Reference(ConstantMap pool, long key) {

            this.pool = pool;

            this.key = key;

        }

        Object resolve() {

            return pool.get(key);

        }

    }

    private final ObjectFactory<?> factory;

    private final LongMap<Object> objects;

    private LongMap<Boolean> isResolving;

    private boolean allResolved;

    private String name;

    ConstantMap(ObjectFactory<?> factory, String name) {

        this.name = name;

        this.objects = new LongMap<>();

        this.factory = factory;

    }

    Object get(long id) {

        // fast path, all objects in pool resolved

        if (allResolved) {

            return objects.get(id);

        }

        // referenced from a pool, deal with this later

        if (isResolving == null) {

            return new Reference(this, id);

        }

        Boolean beingResolved = isResolving.get(id);

        // we are resolved (but not the whole pool)

        if (Boolean.FALSE.equals(beingResolved)) {

            return objects.get(id);

        }

        // resolving ourself, abort to avoid infinite recursion

        if (Boolean.TRUE.equals(beingResolved)) {

            return null;

        }

        // resolve me!

        isResolving.put(id, Boolean.TRUE);

        Object resolved = resolve(objects.get(id));

        isResolving.put(id, Boolean.FALSE);

        if (factory != null) {

            Object factorized = factory.createObject(id, resolved);

            objects.put(id, factorized);

            return factorized;

        } else {

            objects.put(id, resolved);

            return resolved;

        }

    }

    private static Object resolve(Object o) {

        if (o instanceof Reference) {

            return resolve(((Reference) o).resolve());

        }

        if (o != null && o.getClass().isArray()) {

            final Object[] array = (Object[]) o;

            for (int i = 0; i < array.length; i++) {

                array[i] = resolve(array[i]);

            }

            return array;

        }

        return o;

    }

    public void resolve() {

        List<Long> keyList = new ArrayList<>();

        objects.keys().forEachRemaining(keyList::add);

        for (Long l : keyList) {

            get(l);

        }

    }

    public void put(long key, Object value) {

        objects.put(key, value);

    }

    public void setIsResolving() {

        isResolving = new LongMap<>();

    }

    public void setResolved() {

        allResolved = true;

        isResolving = null; // pool finished, release memory

    }

    public String getName() {

        return name;

    }

}