/*
 * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package jdk.jfr.internal.consumer;

import jdk.jfr.internal.LogLevel;
import jdk.jfr.internal.LogTag;
import jdk.jfr.internal.Logger;

import jdk.jfr.internal.LongMap;
import jdk.jfr.internal.Type;

/**
 * Holds mapping between a set of keys and their corresponding object.
 *
 * If the type is a known type, i.e. {@link jdk.jfr.consumer.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();

    final ObjectFactory<?> factory;
    final Type type;
    private final LongMap<Object> objects;
    private boolean resolving;
    private boolean allResolved;

    private ConstantMap() {
        this(null, null);
        allResolved = true;
    }

    ConstantMap(ObjectFactory<?> factory, Type type) {
        this.type = type;
        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 ideally always have a value
        Object value = objects.get(id);
        if (value == null) {
            // unless id is 0 which is used to represent null
            if (id != 0) {
                String msg = "Missing object ID " + id + " in pool " + getName() + ". All IDs should reference an object";
                Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, msg);
                assert false : msg;
            }
            return null;
        }

        // 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 r) {
            return resolve(r.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) {
        if (objects.hasKey(key)) {
            objects.clearId(key);
        }
        objects.put(key, value);
    }

    public void setResolving() {
        resolving = true;
        allResolved = false;
    }

    public void setResolved() {
        allResolved = true;
        resolving = false;
    }

    public String getName() {
        return type == null ? "<empty>" : type.getName();
    }

    // Can be null
    public Type getType() {
        return type;
    }

    public Object getResolved(long id) {
        return objects.get(id);
    }

    public void putResolved(long id, Object object) {
        objects.put(id, object);
        objects.setId(id, RESOLUTION_FINISHED);
    }

    public void setAllResolved(boolean allResolved) {
        this.allResolved = allResolved;
    }

    public LongMap<Object> getObjects() {
       return objects;
    }
}
