common/src/main/java/org/apache/cassandra/sidecar/common/data/XXHash32Digest.java

/*
 * 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.sidecar.common.data;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import static org.apache.cassandra.sidecar.common.http.SidecarHttpHeaderNames.CONTENT_XXHASH32;
import static org.apache.cassandra.sidecar.common.http.SidecarHttpHeaderNames.CONTENT_XXHASH32_SEED;

/**
 * Implements the XXHash32 Digest
 */
public class XXHash32Digest implements Digest
{
    private final @NotNull String value;
    private final @Nullable String seedHex;

    /**
     * Constructs a new XXHashDigest with the provided XXHash {@code value}
     *
     * @param value the xxhash value
     */
    public XXHash32Digest(String value)
    {
        this(value, null);
    }

    /**
     * Constructs a new instance with the provided XXHash {@code value} and the {@code seed} value.
     *
     * @param value the xxhash value
     * @param seed  the seed
     */
    public XXHash32Digest(String value, int seed)
    {
        this(value, Integer.toHexString(seed));
    }

    /**
     * Constructs a new XXHashDigest with the provided XXHash {@code value} and the seed value represented as
     * a hexadecimal string
     *
     * @param value   the xxhash value
     * @param seedHex the value of the seed represented as a hexadecimal value
     */
    public XXHash32Digest(@NotNull String value, @Nullable String seedHex)
    {
        this.value = Objects.requireNonNull(value, "value is required");
        this.seedHex = seedHex;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String value()
    {
        return value;
    }

    /**
     * @return the optional seed in hexadecimal format
     */
    public @Nullable String seedHex()
    {
        return seedHex;
    }

    @Override
    public String algorithm()
    {
        return "XXHash32";
    }

    /**
     * @return XXHash headers for the digest
     */
    @Override
    public Map<String, String> headers()
    {
        Map<String, String> headers = new HashMap<>();
        headers.put(CONTENT_XXHASH32, value);
        if (seedHex != null)
        {
            headers.put(CONTENT_XXHASH32_SEED, seedHex);
        }
        return headers;
    }
}