/*

 * 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 java.lang.invoke.SwitchPoint;

import java.lang.ref.WeakReference;

import java.util.Arrays;

import java.util.Collection;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedHashMap;

import java.util.Map;

import java.util.NoSuchElementException;

import java.util.WeakHashMap;

/**

 * 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>, PropertyListener {

    /** 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;

    /** This mask is used to preserve certain flags when cloning the PropertyMap. Others should not be copied */

    private static final int CLONEABLE_FLAGS_MASK = 0b0000_1111;

    /** Has a listener been added to this property map. This flag is not copied when cloning a map. See {@link PropertyListener} */

    public static final int IS_LISTENER_ADDED     = 0b0001_0000;

    /** Is this process wide "shared" map?. This flag is not copied when cloning a map */

    public static final int IS_SHARED             = 0b0010_0000;

    /** Map status flags. */

    private int flags;

    /** Map of properties. */

    private final PropertyHashMap properties;

    /** Number of fields in use. */

    private int fieldCount;

    /** Number of fields available. */

    private int fieldMaximum;

    /** Length of spill in use. */

    private int spillLength;

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

    private Map<String, SwitchPoint> protoGetSwitches;

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

    private HashMap<Property, PropertyMap> history;

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

    private WeakHashMap<ScriptObject, WeakReference<PropertyMap>> protoHistory;

    /** Cache for hashCode */

    private int hashCode;

    /**

     * 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.

     */

    private PropertyMap(final PropertyHashMap properties, final int fieldCount, final int fieldMaximum, final int spillLength) {

        this.properties   = properties;

        this.fieldCount   = fieldCount;

        this.fieldMaximum = fieldMaximum;

        this.spillLength  = spillLength;

        if (Context.DEBUG) {

            count++;

        }

    }

    /**

     * Constructor.

     *

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

     */

    private PropertyMap(final PropertyHashMap properties) {

        this(properties, 0, 0, 0);

    }

    /**

     * 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.getClonedFlags();

        this.spillLength  = propertyMap.spillLength;

        this.fieldCount   = propertyMap.fieldCount;

        this.fieldMaximum = propertyMap.fieldMaximum;

        if (Context.DEBUG) {

            count++;

            clonedCount++;

        }

    }

    /**

     * Cloning constructor.

     *

     * @param propertyMap Existing property map.

      */

    private PropertyMap(final PropertyMap propertyMap) {

        this(propertyMap, propertyMap.properties);

    }

    /**

     * Duplicates this PropertyMap instance. This is used to duplicate 'shared'

     * maps {@link PropertyMap} used as process wide singletons. Shared maps are

     * duplicated for every global scope object. That way listeners, proto and property

     * histories are scoped within a global scope.

     *

     * @return Duplicated {@link PropertyMap}.

     */

    public PropertyMap duplicate() {

        if (Context.DEBUG) {

            duplicatedCount++;

        }

        return new PropertyMap(this.properties);

    }

    /**

     * Public property map allocator.

     *

     * @param properties   Collection of initial properties.

     * @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 int fieldCount, final int fieldMaximum,  final int spillLength) {

        PropertyHashMap newProperties = EMPTY_HASHMAP.immutableAdd(properties);

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

    }

    /**

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

     * @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, 0, 0, 0);

    }

    /**

     * Return a sharable empty map.

     *

     * @return New empty {@link PropertyMap}.

     */

    public static PropertyMap newMap() {

        return new PropertyMap(EMPTY_HASHMAP);

    }

    /**

     * Return number of properties in the map.

     *

     * @return Number of properties.

     */

    public int size() {

        return properties.size();

    }

    /**

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

     *

     * @param proto  Object prototype.

     * @param key    {@link Property} key.

     *

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

     */

    public SwitchPoint getProtoGetSwitchPoint(final ScriptObject proto, final String key) {

        assert !isShared() : "proto SwitchPoint from a shared PropertyMap";

        if (proto == null) {

            return null;

        }

        if (protoGetSwitches == null) {

            protoGetSwitches = new HashMap<>();

            if (! isListenerAdded()) {

                proto.addPropertyListener(this);

                setIsListenerAdded();

            }

        }

        if (protoGetSwitches.containsKey(key)) {

            return protoGetSwitches.get(key);

        }

        final SwitchPoint switchPoint = new SwitchPoint();

        protoGetSwitches.put(key, switchPoint);

        return switchPoint;

    }

    /**

     * Indicate that a prototype property hash changed.

     *

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

     */

    private void invalidateProtoGetSwitchPoint(final Property property) {

        assert !isShared() : "proto invalidation on a shared PropertyMap";

        if (protoGetSwitches != null) {

            final String key = property.getKey();

            final SwitchPoint sp = protoGetSwitches.get(key);

            if (sp != null) {

                protoGetSwitches.put(key, new SwitchPoint());

                if (Context.DEBUG) {

                    protoInvalidations++;

                }

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

            }

        }

    }

    /**

     * 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) {

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

    }

    /**

     * 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) {

        PropertyMap newMap = checkHistory(property);

        if (newMap == null) {

            final PropertyHashMap newProperties = properties.immutableAdd(property);

            newMap = new PropertyMap(this, newProperties);

            addToHistory(property, newMap);

            if(!property.isSpill()) {

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

            }

            newMap.spillLength += property.getSpillCount();

        }

        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) {

        PropertyMap newMap = checkHistory(property);

        final String key = property.getKey();

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

            final PropertyHashMap newProperties = properties.immutableRemove(key);

            newMap = new PropertyMap(this, newProperties);

            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.

     */

    PropertyMap replaceProperty(final Property oldProperty, final Property newProperty) {

        // Add replaces existing property.

        final PropertyHashMap newProperties = properties.immutableAdd(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:

         *

         *   1. To change flags OR TYPE of an old (cloned) property. We use the same spill slots.

         *   2. To change one UserAccessor property with another - user getter or setter changed via

         *      Object.defineProperty function. Again, same spill slots are re-used.

         *   3. Via ScriptObject.setUserAccessors method to set user getter and setter functions

         *      replacing the dummy AccessorProperty with null method handles (added during map init).

         *

         * In case (1) and case(2), the property type of old and new property is same. For case (3),

         * the old property is an AccessorProperty and the new one is a UserAccessorProperty property.

         */

        final boolean sameType = (oldProperty.getClass() == newProperty.getClass());

        assert sameType ||

                (oldProperty instanceof AccessorProperty &&

                newProperty instanceof UserAccessorProperty) : "arbitrary replaceProperty attempted";

        newMap.flags = getClonedFlags();

        /*

         * spillLength remains same in case (1) and (2) because of slot reuse. Only for case (3), we need

         * to add spill count of the newly added UserAccessorProperty property.

         */

        newMap.spillLength = spillLength + (sameType? 0 : newProperty.getSpillCount());

        return newMap;

    }

     * Make a new UserAccessorProperty property. getter and setter functions are stored in

     * this ScriptObject and slot values are used in property object. Note that slots

     * are assigned speculatively and should be added to map before adding other

     * properties.

     */

    public UserAccessorProperty newUserAccessors(final String key, final int propertyFlags) {

        int oldSpillLength = spillLength;

        final int getterSlot = oldSpillLength++;

        final int setterSlot = oldSpillLength++;

        return new UserAccessorProperty(key, propertyFlags, getterSlot, setterSlot);

    }

    /**

     * Find a property in the map.

     *

     * @param key Key to search for.

     *

     * @return {@link Property} matching key.

     */

    public Property findProperty(final String key) {

        return properties.find(key);

    }

    /**

     * Adds all map properties from another map.

     *

     * @param other The source of properties.

     *

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

     */

    public PropertyMap addAll(final PropertyMap other) {

        assert this != other : "adding property map to itself";

        final Property[] otherProperties = other.properties.getProperties();

        final PropertyHashMap newProperties = properties.immutableAdd(otherProperties);

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

        for (final Property property : otherProperties) {

            newMap.spillLength += property.getSpillCount();

        }

        return newMap;

    }

    /**

     * Return an array of all properties.

     *

     * @return Properties as an array.

     */

    public Property[] getProperties() {

        return properties.getProperties();

    }

    /**

     * Prevents the map from having additional properties.

     *

     * @return New map with {@link #NOT_EXTENSIBLE} flag set.

     */

    PropertyMap preventExtensions() {

        final PropertyMap newMap = new PropertyMap(this);

        newMap.flags |= NOT_EXTENSIBLE;

        return newMap;

    }

    /**

     * Prevents properties in map from being modified.

     *

     * @return New map with {@link #NOT_EXTENSIBLE} flag set and properties with

     * {@link Property#NOT_CONFIGURABLE} set.

     */

    PropertyMap seal() {

        PropertyHashMap newProperties = EMPTY_HASHMAP;

        for (final Property oldProperty :  properties.getProperties()) {

            newProperties = newProperties.immutableAdd(oldProperty.addFlags(Property.NOT_CONFIGURABLE));

        }

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

        newMap.flags |= NOT_EXTENSIBLE;

        return newMap;

    }

    /**

     * Prevents properties in map from being modified or written to.

     *

     * @return New map with {@link #NOT_EXTENSIBLE} flag set and properties with

     * {@link Property#NOT_CONFIGURABLE} and {@link Property#NOT_WRITABLE} set.

     */

    PropertyMap freeze() {

        PropertyHashMap newProperties = EMPTY_HASHMAP;

        for (Property oldProperty : properties.getProperties()) {

            int propertyFlags = Property.NOT_CONFIGURABLE;

            if (!(oldProperty instanceof UserAccessorProperty)) {

                propertyFlags |= Property.NOT_WRITABLE;

            }

            newProperties = newProperties.immutableAdd(oldProperty.addFlags(propertyFlags));

        }

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

        newMap.flags |= NOT_EXTENSIBLE;

        return newMap;

    }

    /**

     * Make this property map 'shared' one. Shared property map instances are

     * process wide singleton objects. A shaped map should never be added as a listener

     * to a proto object. Nor it should have history or proto history. A shared map

     * is just a template that is meant to be duplicated before use. All nasgen initialized

     * property maps are shared.

     *

     * @return this map after making it as shared

     */

    public PropertyMap setIsShared() {

        assert !isListenerAdded() : "making PropertyMap shared after listener added";

        assert protoHistory == null : "making PropertyMap shared after associating a proto with it";

        if (Context.DEBUG) {

            sharedCount++;

        }

        flags |= IS_SHARED;

        // clear any history on this PropertyMap, won't be used.

        history = null;

        return this;

    }

    /**

     * Check for any configurable properties.

     *

     * @return {@code true} if any configurable.

     */

    private boolean anyConfigurable() {

        for (final Property property : properties.getProperties()) {

            if (property.isConfigurable()) {

               return true;

            }

        }

        return false;

    }

    /**

     * Check if all properties are frozen.

     *

     * @return {@code true} if all are frozen.

     */

    private boolean allFrozen() {

        for (final Property property : properties.getProperties()) {

            // check if it is a data descriptor

            if (!(property instanceof UserAccessorProperty)) {