/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.cassandra.db;

import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.util.Objects;

import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.ObjectSizes;

public abstract class AbstractClusteringPrefix implements ClusteringPrefix
{
    protected static final ByteBuffer[] EMPTY_VALUES_ARRAY = new ByteBuffer[0];

    private static final long EMPTY_SIZE = ObjectSizes.measure(new Clustering(EMPTY_VALUES_ARRAY));

    protected final Kind kind;
    protected final ByteBuffer[] values;

    protected AbstractClusteringPrefix(Kind kind, ByteBuffer[] values)
    {
        this.kind = kind;
        this.values = values;
    }

    public Kind kind()
    {
        return kind;
    }

    public ClusteringPrefix clustering()
    {
        return this;
    }

    public int size()
    {
        return values.length;
    }

    public ByteBuffer get(int i)
    {
        return values[i];
    }

    public ByteBuffer[] getRawValues()
    {
        return values;
    }

    public int dataSize()
    {
        int size = 0;
        for (int i = 0; i < size(); i++)
        {
            ByteBuffer bb = get(i);
            size += bb == null ? 0 : bb.remaining();
        }
        return size;
    }

    public void digest(MessageDigest digest)
    {
        for (int i = 0; i < size(); i++)
        {
            ByteBuffer bb = get(i);
            if (bb != null)
                digest.update(bb.duplicate());
        }
        FBUtilities.updateWithByte(digest, kind().ordinal());
    }

    public long unsharedHeapSize()
    {
        return EMPTY_SIZE + ObjectSizes.sizeOnHeapOf(values);
    }

    public long unsharedHeapSizeExcludingData()
    {
        return EMPTY_SIZE + ObjectSizes.sizeOnHeapExcludingData(values);
    }

    @Override
    public final int hashCode()
    {
        int result = 31;
        for (int i = 0; i < size(); i++)
            result += 31 * Objects.hashCode(get(i));
        return 31 * result + Objects.hashCode(kind());
    }

    @Override
    public final boolean equals(Object o)
    {
        if(!(o instanceof ClusteringPrefix))
            return false;

        ClusteringPrefix that = (ClusteringPrefix)o;
        if (this.kind() != that.kind() || this.size() != that.size())
            return false;

        for (int i = 0; i < size(); i++)
            if (!Objects.equals(this.get(i), that.get(i)))
                return false;

        return true;
    }
}