/*

 * Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.runtime;

import static jdk.nashorn.internal.runtime.PropertyHashMap.EMPTY_HASHMAP;

import static jdk.nashorn.internal.runtime.arrays.ArrayIndex.getArrayIndex;

import static jdk.nashorn.internal.runtime.arrays.ArrayIndex.isValidArrayIndex;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.Serializable;

import java.lang.invoke.SwitchPoint;

import java.lang.ref.SoftReference;

import java.util.Arrays;

import java.util.BitSet;

import java.util.Collection;

import java.util.HashMap;

import java.util.Iterator;

import java.util.NoSuchElementException;

import java.util.WeakHashMap;

import jdk.nashorn.internal.scripts.JO;

/**

 * Map of object properties. The PropertyMap is the "template" for JavaScript object

 * layouts. It contains a map with prototype names as keys and {@link Property} instances

 * as values. A PropertyMap is typically passed to the {@link ScriptObject} constructor

 * to form the seed map for the ScriptObject.

 * <p>

 * All property maps are immutable. If a property is added, modified or removed, the mutator

 * will return a new map.

 */

public final class PropertyMap implements Iterable<Object>, Serializable {

    /** Used for non extensible PropertyMaps, negative logic as the normal case is extensible. See {@link ScriptObject#preventExtensions()} */

    public static final int NOT_EXTENSIBLE        = 0b0000_0001;

    /** Does this map contain valid array keys? */

    public static final int CONTAINS_ARRAY_KEYS   = 0b0000_0010;

    /** Map status flags. */

    private int flags;

    /** Map of properties. */

    private transient PropertyHashMap properties;

    /** Number of fields in use. */

    private int fieldCount;

    /** Number of fields available. */

    private final int fieldMaximum;

    /** Length of spill in use. */

    private int spillLength;

    /** Structure class name */

    private String className;

    /** {@link SwitchPoint}s for gets on inherited properties. */

    private transient HashMap<String, SwitchPoint> protoGetSwitches;

    /** History of maps, used to limit map duplication. */

    private transient WeakHashMap<Property, SoftReference<PropertyMap>> history;

    /** History of prototypes, used to limit map duplication. */

    private transient WeakHashMap<ScriptObject, SoftReference<PropertyMap>> protoHistory;

    /** property listeners */

    private transient PropertyListeners listeners;

    private transient BitSet freeSlots;

    private static final long serialVersionUID = -7041836752008732533L;

    /**

     * Constructor.

     *

     * @param properties   A {@link PropertyHashMap} with initial contents.

     * @param fieldCount   Number of fields in use.

     * @param fieldMaximum Number of fields available.

     * @param spillLength  Number of spill slots used.

     * @param containsArrayKeys True if properties contain numeric keys

     */

    private PropertyMap(final PropertyHashMap properties, final String className, final int fieldCount,

                        final int fieldMaximum, final int spillLength, final boolean containsArrayKeys) {

        this.properties   = properties;

        this.className    = className;

        this.fieldCount   = fieldCount;

        this.fieldMaximum = fieldMaximum;

        this.spillLength  = spillLength;

        if (containsArrayKeys) {

            setContainsArrayKeys();

        }

        if (Context.DEBUG) {

            count++;

        }

    }

    /**

     * Cloning constructor.

     *

     * @param propertyMap Existing property map.

     * @param properties  A {@link PropertyHashMap} with a new set of properties.

     */

    private PropertyMap(final PropertyMap propertyMap, final PropertyHashMap properties) {

        this.properties   = properties;

        this.flags        = propertyMap.flags;

        this.spillLength  = propertyMap.spillLength;

        this.fieldCount   = propertyMap.fieldCount;

        this.fieldMaximum = propertyMap.fieldMaximum;

        // We inherit the parent property listeners instance. It will be cloned when a new listener is added.

        this.listeners    = propertyMap.listeners;

        this.freeSlots    = propertyMap.freeSlots;

        if (Context.DEBUG) {

            count++;

            clonedCount++;

        }

    }

    /**

     * Cloning constructor.

     *

     * @param propertyMap Existing property map.

      */

    private PropertyMap(final PropertyMap propertyMap) {

        this(propertyMap, propertyMap.properties);

    }

    private void writeObject(final ObjectOutputStream out) throws IOException {

        out.defaultWriteObject();

        out.writeObject(properties.getProperties());

    }

    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {

        in.defaultReadObject();

        final Property[] props = (Property[]) in.readObject();

        this.properties = EMPTY_HASHMAP.immutableAdd(props);

        assert className != null;

        final Class<?> structure = Context.forStructureClass(className);

        for (final Property prop : props) {

            prop.initMethodHandles(structure);

        }

    }

    /**

     * Public property map allocator.

     *

     * <p>It is the caller's responsibility to make sure that {@code properties} does not contain

     * properties with keys that are valid array indices.</p>

     *

     * @param properties   Collection of initial properties.

     * @param className    class name

     * @param fieldCount   Number of fields in use.

     * @param fieldMaximum Number of fields available.

     * @param spillLength  Number of used spill slots.

     * @return New {@link PropertyMap}.

     */

    public static PropertyMap newMap(final Collection<Property> properties, final String className, final int fieldCount, final int fieldMaximum,  final int spillLength) {

        final PropertyHashMap newProperties = EMPTY_HASHMAP.immutableAdd(properties);

        return new PropertyMap(newProperties, className, fieldCount, fieldMaximum, spillLength, false);

    }

    /**

     * Public property map allocator. Used by nasgen generated code.

     *

     * <p>It is the caller's responsibility to make sure that {@code properties} does not contain

     * properties with keys that are valid array indices.</p>

     *

     * @param properties Collection of initial properties.

     * @return New {@link PropertyMap}.

     */

    public static PropertyMap newMap(final Collection<Property> properties) {

        return properties == null || properties.isEmpty()? newMap() : newMap(properties, JO.class.getName(), 0, 0, 0);

    }

    /**

     * Return a sharable empty map.

     *

     * @return New empty {@link PropertyMap}.

     */

    public static PropertyMap newMap() {

        return new PropertyMap(EMPTY_HASHMAP, JO.class.getName(), 0, 0, 0, false);

    }

    /**

     * Return number of properties in the map.

     *

     * @return Number of properties.

     */

    public int size() {

        return properties.size();

    }

    /**

     * Get the listeners of this map, or null if none exists

     *

     * @return the listeners

     */

    public PropertyListeners getListeners() {

        return listeners;

    }

    /**

     * Add {@code listenerMap} as a listener to this property map for the given {@code key}.

     *

     * @param key the property name

     * @param listenerMap the listener map

     */

    public void addListener(final String key, final PropertyMap listenerMap) {

        if (listenerMap != this) {

            // We need to clone listener instance when adding a new listener since we share

            // the listeners instance with our parent maps that don't need to see the new listener.

            listeners = PropertyListeners.addListener(listeners, key, listenerMap);

        }

    }

    /**

     * A new property is being added.

     *

     * @param property The new Property added.

     */

    public void propertyAdded(final Property property) {

        invalidateProtoGetSwitchPoint(property);

        if (listeners != null) {

            listeners.propertyAdded(property);

        }

    }

    /**

     * An existing property is being deleted.

     *

     * @param property The property being deleted.

     */

    public void propertyDeleted(final Property property) {

        invalidateProtoGetSwitchPoint(property);

        if (listeners != null) {

            listeners.propertyDeleted(property);

        }

    }

    /**

     * An existing property is being redefined.

     *

     * @param oldProperty The old property

     * @param newProperty The new property

     */

    public void propertyModified(final Property oldProperty, final Property newProperty) {

        invalidateProtoGetSwitchPoint(oldProperty);

        if (listeners != null) {

            listeners.propertyModified(oldProperty, newProperty);

        }

    }

    /**

     * The prototype of an object associated with this {@link PropertyMap} is changed.

     */

    public void protoChanged() {

        invalidateAllProtoGetSwitchPoints();

        if (listeners != null) {

            listeners.protoChanged();

        }

    }

    /**

     * Return a SwitchPoint used to track changes of a property in a prototype.

     *

     * @param key Property key.

     * @return A shared {@link SwitchPoint} for the property.

     */

    public synchronized SwitchPoint getSwitchPoint(final String key) {

        if (protoGetSwitches == null) {

            protoGetSwitches = new HashMap<>();

        }

        SwitchPoint switchPoint = protoGetSwitches.get(key);

        if (switchPoint == null) {

            switchPoint = new SwitchPoint();

            protoGetSwitches.put(key, switchPoint);

        }

        return switchPoint;

    }

    /**

     * Indicate that a prototype property has changed.

     *

     * @param property {@link Property} to invalidate.

     */

    synchronized void invalidateProtoGetSwitchPoint(final Property property) {

        if (protoGetSwitches != null) {

            final String key = property.getKey();

            final SwitchPoint sp = protoGetSwitches.get(key);

            if (sp != null) {

                protoGetSwitches.remove(key);

                if (Context.DEBUG) {

                    protoInvalidations++;

                }

                SwitchPoint.invalidateAll(new SwitchPoint[] { sp });

            }

        }

    }

    /**

     * Indicate that proto itself has changed in hierarchy somewhere.

     */

    synchronized void invalidateAllProtoGetSwitchPoints() {

        if (protoGetSwitches != null && !protoGetSwitches.isEmpty()) {

            if (Context.DEBUG) {

                protoInvalidations += protoGetSwitches.size();

            }

            SwitchPoint.invalidateAll(protoGetSwitches.values().toArray(new SwitchPoint[protoGetSwitches.values().size()]));

            protoGetSwitches.clear();

        }

    }

    /**

     * Add a property to the map, re-binding its getters and setters,

     * if available, to a given receiver. This is typically the global scope. See

     * {@link ScriptObject#addBoundProperties(ScriptObject)}

     *

     * @param property {@link Property} being added.

     * @param bindTo   Object to bind to.

     *

     * @return New {@link PropertyMap} with {@link Property} added.

     */

    PropertyMap addPropertyBind(final AccessorProperty property, final Object bindTo) {

        // No need to store bound property in the history as bound properties can't be reused.

        return addPropertyNoHistory(new AccessorProperty(property, bindTo));

    }

    // Get a logical slot index for a property, with spill slot 0 starting at fieldMaximum.

    private int logicalSlotIndex(final Property property) {

        final int slot = property.getSlot();

        if (slot < 0) {

            return -1;

        }

        return property.isSpill() ? slot + fieldMaximum : slot;

    }

    // Update boundaries and flags after a property has been added

    private void updateFlagsAndBoundaries(final Property newProperty) {

        if(newProperty.isSpill()) {

            spillLength = Math.max(spillLength, newProperty.getSlot() + 1);

        } else {

            fieldCount = Math.max(fieldCount, newProperty.getSlot() + 1);

        }

        if (isValidArrayIndex(getArrayIndex(newProperty.getKey()))) {

            setContainsArrayKeys();

        }

    }

    // Update the free slots bitmap for a property that has been deleted and/or added.

    private void updateFreeSlots(final Property oldProperty, final Property newProperty) {

        // Free slots bitset is possibly shared with parent map, so we must clone it before making modifications.

        boolean freeSlotsCloned = false;

        if (oldProperty != null) {

            final int slotIndex = logicalSlotIndex(oldProperty);

            if (slotIndex >= 0) {

                final BitSet newFreeSlots = freeSlots == null ? new BitSet() : (BitSet)freeSlots.clone();

                assert !newFreeSlots.get(slotIndex);

                newFreeSlots.set(slotIndex);

                freeSlots = newFreeSlots;

                freeSlotsCloned = true;

            }

        }

        if (freeSlots != null && newProperty != null) {

            final int slotIndex = logicalSlotIndex(newProperty);

            if (slotIndex > -1 && freeSlots.get(slotIndex)) {

                final BitSet newFreeSlots = freeSlotsCloned ? freeSlots : ((BitSet)freeSlots.clone());

                newFreeSlots.clear(slotIndex);

                freeSlots = newFreeSlots.isEmpty() ? null : newFreeSlots;

            }

        }

    }

    /**

     * Add a property to the map without adding it to the history. This should be used for properties that

     * can't be shared such as bound properties, or properties that are expected to be added only once.

     *

     * @param property {@link Property} being added.

     * @return New {@link PropertyMap} with {@link Property} added.

     */

    public PropertyMap addPropertyNoHistory(final Property property) {

        if (listeners != null) {

            listeners.propertyAdded(property);

        }

        final PropertyHashMap newProperties = properties.immutableAdd(property);

        final PropertyMap newMap = new PropertyMap(this, newProperties);

        newMap.updateFlagsAndBoundaries(property);

        newMap.updateFreeSlots(null, property);

        return newMap;

    }

    /**

     * Add a property to the map.  Cloning or using an existing map if available.

     *

     * @param property {@link Property} being added.

     *

     * @return New {@link PropertyMap} with {@link Property} added.

     */

    public PropertyMap addProperty(final Property property) {

        if (listeners != null) {

            listeners.propertyAdded(property);

        }

        PropertyMap newMap = checkHistory(property);

        if (newMap == null) {

            final PropertyHashMap newProperties = properties.immutableAdd(property);

            newMap = new PropertyMap(this, newProperties);

            addToHistory(property, newMap);

            newMap.updateFlagsAndBoundaries(property);

            newMap.updateFreeSlots(null, property);

        }

        return newMap;

    }

    /**

     * Remove a property from a map. Cloning or using an existing map if available.

     *

     * @param property {@link Property} being removed.

     *

     * @return New {@link PropertyMap} with {@link Property} removed or {@code null} if not found.

     */

    public PropertyMap deleteProperty(final Property property) {

        if (listeners != null) {

            listeners.propertyDeleted(property);

        }

        PropertyMap newMap = checkHistory(property);

        final String key = property.getKey();

        if (newMap == null && properties.containsKey(key)) {

            final PropertyHashMap newProperties = properties.immutableRemove(key);

            final boolean isSpill = property.isSpill();

            final int slot = property.getSlot();

            // If deleted property was last field or spill slot we can make it reusable by reducing field/slot count.

            // Otherwise mark it as free in free slots bitset.

            if (isSpill && slot >= 0 && slot == spillLength - 1) {

                newMap = new PropertyMap(newProperties, className, fieldCount, fieldMaximum, spillLength - 1, containsArrayKeys());

                newMap.freeSlots = freeSlots;

            } else if (!isSpill && slot >= 0 && slot == fieldCount - 1) {

                newMap = new PropertyMap(newProperties, className, fieldCount - 1, fieldMaximum, spillLength, containsArrayKeys());

                newMap.freeSlots = freeSlots;

            } else {

                newMap = new PropertyMap(this, newProperties);

                newMap.updateFreeSlots(property, null);

            }

            addToHistory(property, newMap);

        }

        return newMap;

    }

    /**

     * Replace an existing property with a new one.

     *

     * @param oldProperty Property to replace.

     * @param newProperty New {@link Property}.

     *

     * @return New {@link PropertyMap} with {@link Property} replaced.

     */

        if (listeners != null) {

            listeners.propertyModified(oldProperty, newProperty);

        }

        // Add replaces existing property.

        final PropertyHashMap newProperties = properties.immutableReplace(oldProperty, newProperty);

        final PropertyMap newMap = new PropertyMap(this, newProperties);

        /*

         * See ScriptObject.modifyProperty and ScriptObject.setUserAccessors methods.

         *

         * This replaceProperty method is called only for the following three cases:

         *