/*
 * 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.tomcat.util.codec.binary;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

/**
 * Converts String to and from bytes using the encodings required by the Java specification. These encodings are
 * specified in <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/nio/charset/Charset.html">
 * Standard charsets</a>.
 * <p>
 * This class is immutable and thread-safe.
 * </p>
 *
 * @see Charset
 * @see StandardCharsets
 *
 * @since 1.4
 *
 * @deprecated Unused. This class will be removed in Tomcat 11 onwards.
 */
@Deprecated
public class StringUtils {

    /**
     * Calls {@link String#getBytes(Charset)}
     *
     * @param string  The string to encode (if null, return null).
     * @param charset The {@link Charset} to encode the {@code String}
     *
     * @return the encoded bytes
     */
    private static byte[] getBytes(final String string, final Charset charset) {
        return string == null ? null : string.getBytes(charset);
    }

    /**
     * Encodes the given string into a sequence of bytes using the UTF-8 charset, storing the result into a new byte
     * array.
     *
     * @param string the String to encode, may be {@code null}
     *
     * @return encoded bytes, or {@code null} if the input string was {@code null}
     *
     * @throws NullPointerException Thrown if {@link StandardCharsets#UTF_8} is not initialized, which should never
     *                                  happen since it is required by the Java platform specification.
     *
     * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException
     *
     * @see Charset
     */
    public static byte[] getBytesUtf8(final String string) {
        return getBytes(string, StandardCharsets.UTF_8);
    }

    /**
     * Constructs a new {@code String} by decoding the specified array of bytes using the given charset.
     *
     * @param bytes   The bytes to be decoded into characters
     * @param charset The {@link Charset} to encode the {@code String}; not {@code null}
     *
     * @return A new {@code String} decoded from the specified array of bytes using the given charset, or {@code null}
     *             if the input byte array was {@code null}.
     *
     * @throws NullPointerException Thrown if charset is {@code null}
     */
    private static String newString(final byte[] bytes, final Charset charset) {
        return bytes == null ? null : new String(bytes, charset);
    }

    /**
     * Constructs a new {@code String} by decoding the specified array of bytes using the US-ASCII charset.
     *
     * @param bytes The bytes to be decoded into characters
     *
     * @return A new {@code String} decoded from the specified array of bytes using the US-ASCII charset, or
     *             {@code null} if the input byte array was {@code null}.
     *
     * @throws NullPointerException Thrown if {@link StandardCharsets#US_ASCII} is not initialized, which should never
     *                                  happen since it is required by the Java platform specification.
     *
     * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException
     */
    public static String newStringUsAscii(final byte[] bytes) {
        return newString(bytes, StandardCharsets.US_ASCII);
    }

    /**
     * Constructs a new {@code String} by decoding the specified array of bytes using the UTF-8 charset.
     *
     * @param bytes The bytes to be decoded into characters
     *
     * @return A new {@code String} decoded from the specified array of bytes using the UTF-8 charset, or {@code null}
     *             if the input byte array was {@code null}.
     *
     * @throws NullPointerException Thrown if {@link StandardCharsets#UTF_8} is not initialized, which should never
     *                                  happen since it is required by the Java platform specification.
     *
     * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException
     */
    public static String newStringUtf8(final byte[] bytes) {
        return newString(bytes, StandardCharsets.UTF_8);
    }

    private StringUtils() {
        // empty
    }
}