/*

 * Copyright (c) 2016, 2019, 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;

/**

 * 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 static final int RESOLUTION_FINISHED = 0;

    private static final int RESOLUTION_STARTED = 1;

    public static final ConstantMap EMPTY = new ConstantMap();

    // A temporary placeholder, so objects can

    // reference themselves (directly, or indirectly),

    // when making a transition from numeric id references

    // to normal Java references.

    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);

        }

        public String toString() {

            return "ref: " + pool.name + "[" + key + "]";

        }

    }

    final ObjectFactory<?> factory;

    final String name;

    private final LongMap<Object> objects;

    private boolean resolving;

    private boolean allResolved;

    private ConstantMap() {

        this(null, "<empty>");

        allResolved = true;

    }

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

        this.name = name;

        this.objects = new LongMap<>(2);

        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 (!resolving) {

            return new Reference(this, id);

        }

        // should always have a value

        Object value = objects.get(id);

        if (value == null) {

            // unless is 0 which is used to represent null

            if (id == 0) {

                return null;

            }

            throw new InternalError("Missing object id=" + id + " in pool " + name + ". All ids should reference object");

        }

        // id is resolved (but not the whole pool)

        if (objects.isSetId(id, RESOLUTION_FINISHED)) {

            return value;

        }

        // resolving ourself, abort to avoid infinite recursion

        if (objects.isSetId(id, RESOLUTION_STARTED)) {

            return null;

        }

        // mark id as STARTED if we should

        // come back during object resolution

        objects.setId(id, RESOLUTION_STARTED);

        // resolve object!

        Object resolved = resolve(value);

        // mark id as FINISHED

        objects.setId(id, RESOLUTION_FINISHED);

        // if a factory exists, convert to RecordedThread.

        // RecordedClass etc. and store back results

        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++) {

                Object element = array[i];

                array[i] = resolve(element);

            }

            return array;

        }

        return o;

    }

    public void resolve() {

        objects.forEachKey(k -> get(k));

    }

    public void put(long key, Object value) {

        objects.put(key, value);

    }

    public void setResolving() {

        resolving = true;

        allResolved = false;

    }

    public void setResolved() {

        allResolved = true;

        resolving = false;

    }

    public String getName() {

        return name;

    }

    public Object getResolved(long id) {

        return objects.get(id);

    }

    public void putResolved(long id, Object object) {

        objects.setId(id, RESOLUTION_FINISHED);

        objects.put(id, object);

    }

    public void setAllResolved(boolean allResolved) {

        this.allResolved = allResolved;

    }

    public boolean isResolved(long id) {

        if (objects.hasKey(id)) {

            return objects.isSetId(id, RESOLUTION_FINISHED);

        }

        return false;

    }

}