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There is a newer version: 8.16.0

/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.common.lucene;

import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.util.BytesRef;

public class BytesRefs {

    /**
     * Converts a value to a string, taking special care if its a {@link BytesRef} to call
     * {@link org.apache.lucene.util.BytesRef#utf8ToString()}.
     */
    public static String toString(Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof BytesRef) {
            return ((BytesRef) value).utf8ToString();
        }
        return value.toString();
    }

    /**
     * Converts an object value to BytesRef.
     */
    public static BytesRef toBytesRef(Object value) {
        if (value == null) {
            return null;
        }
        if (value instanceof BytesRef) {
            return (BytesRef) value;
        }
        return new BytesRef(value.toString());
    }

    /**
     * Checks that the input is not longer than {@link IndexWriter#MAX_TERM_LENGTH}
     * @param input a BytesRef
     * @return the same BytesRef, if no exception has been thrown
     * @throws IllegalArgumentException if the input is too long
     */
    public static BytesRef checkIndexableLength(BytesRef input) {
        if (input.length > IndexWriter.MAX_TERM_LENGTH) {
            throw new IllegalArgumentException(
                "Term is longer than maximum indexable length, term starting with [" + safeStringPrefix(input, 10)
            );
        }
        return input;
    }

    /**
     * Produces a UTF-string prefix of the input BytesRef.  If the prefix cutoff would produce
     * ill-formed UTF, it falls back to the hexadecimal representation.
     * @param input an input BytesRef
     * @return a String prefix
     */
    private static String safeStringPrefix(BytesRef input, int prefixLength) {
        BytesRef prefix = new BytesRef(input.bytes, input.offset, prefixLength);
        try {
            return prefix.utf8ToString();
        } catch (Exception e) {
            return prefix.toString();
        }
    }

}