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/*
 * Copyright (C) 2021-2024 Hedera Hashgraph, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.swirlds.merkle.map.internal;

import com.swirlds.common.FastCopyable;
import com.swirlds.common.io.SelfSerializable;
import com.swirlds.common.merkle.MerkleInternal;
import com.swirlds.common.merkle.MerkleNode;
import com.swirlds.common.merkle.impl.PartialBinaryMerkleInternal;
import com.swirlds.common.merkle.utility.Keyed;
import com.swirlds.merkle.map.MerkleMap;
import java.util.Objects;

/**
 * A wrapper class designed to be used as a value in a {@link MerkleMap MerkleMap}. Useful when it is inconvenient to
 * store a non-merkle key directly in the value.
 *
 * @param 
 * 		the type of the key in the {@link MerkleMap MerkleMap}. This type SHOULD NOT be a merkle type,
 * 		else there is significant memory overhead
 * @param 
 * 		an arbitrary merkle type that is being stored in the MerkleMap
 */
public class MerkleMapEntry
        extends PartialBinaryMerkleInternal implements Keyed, MerkleInternal {

    private static class ClassVersion {
        public static final int ORIGINAL = 1;
    }

    public static final long CLASS_ID = 0x19bddb9a9d69bfd0L;

    /**
     * Create a new entry.
     *
     * @param key
     * 		the key
     * @param value
     * 		the value
     */
    public MerkleMapEntry(final K key, final V value) {
        super();
        setLeft(new MerkleMapEntryKey(key));
        setRight(value);
    }

    /**
     * Create a new entry without specifying the key.
     * If inserted into a {@link MerkleMap} then the key will automatically be set.
     *
     * @param value
     * 		the value of the entry
     */
    public MerkleMapEntry(final V value) {
        super();
        setRight(value);
    }

    /**
     * Create a new merkle pair.
     */
    public MerkleMapEntry() {
        super();
    }

    /**
     * Copy constructor.
     *
     * @param that
     * 		the node to copy
     */
    protected MerkleMapEntry(final MerkleMapEntry that) {
        super(that);
        that.setImmutable(true);

        if (that.getLeft() != null) {
            setLeft(that.getLeft().copy().cast());
        }
        if (that.getRight() != null) {
            setRight(that.getRight().copy().cast());
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(final Object object) {
        if (this == object) {
            return true;
        }

        if (!(object instanceof MerkleMapEntry)) {
            return false;
        }

        final MerkleMapEntry otherLeaf = (MerkleMapEntry) object;
        return Objects.equals(getLeft(), otherLeaf.getLeft()) && Objects.equals(getRight(), otherLeaf.getRight());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        return Objects.hash(getLeft(), getRight());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public MerkleMapEntry copy() {
        throwIfImmutable();
        throwIfDestroyed();
        return new MerkleMapEntry<>(this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public long getClassId() {
        return CLASS_ID;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int getVersion() {
        return MerkleMapEntry.ClassVersion.ORIGINAL;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public K getKey() {
        final MerkleMapEntryKey key = getLeft();
        return key == null ? null : key.getKey();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setKey(final K key) {
        if (getLeft() == null) {
            setLeft(new MerkleMapEntryKey<>(key));
        } else {
            final MerkleMapEntryKey keyWrapper = getLeft();
            keyWrapper.setKey(key);
        }
    }

    /**
     * Get the value of this entry.
     */
    public V getValue() {
        return getRight();
    }

    /**
     * Set the value of this entry.
     *
     * @param value
     * 		the new value
     */
    public void setValue(final V value) {
        setRight(value);
    }
}