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/**
 * Copyright (c) 2011-2017, 玛雅牛 (myaniu AT gmail dot com).
 *
 * 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.jfinal.kit;

import java.nio.charset.Charset;

public class Base64Kit {

    public static final Charset UTF_8 = Charset.forName("UTF-8");
    private static IBase64 delegate;

    private Base64Kit() {
    }

    static {
        if (isPresent("java.util.Base64", Base64Kit.class.getClassLoader())) {
            delegate = new Java8Base64();
        } else {
            delegate = new Java67Base64();
        }
    }

    /**
     * 编码
     * 
     * @param value
     *            byte数组
     * @return {String}
     */
    public static String encode(byte[] value) {
        return delegate.encode(value);
    }

    /**
     * 编码
     * 
     * @param value
     *            字符串
     * @return {String}
     */
    public static String encode(String value) {
        byte[] val = value.getBytes(UTF_8);
        return delegate.encode(val);
    }

    /**
     * 编码
     * 
     * @param value
     *            字符串
     * @param charsetName
     *            charSet
     * @return {String}
     */
    public static String encode(String value, String charsetName) {
        byte[] val = value.getBytes(Charset.forName(charsetName));
        return delegate.encode(val);
    }

    /**
     * 解码
     * 
     * @param value
     *            字符串
     * @return {byte[]}
     */
    public static byte[] decode(String value) {
        return delegate.decode(value);
    }

    /**
     * 解码
     * 
     * @param value
     *            字符串
     * @return {String}
     */
    public static String decodeToStr(String value) {
        byte[] decodedValue = delegate.decode(value);
        return new String(decodedValue, UTF_8);
    }

    /**
     * 解码
     * 
     * @param value
     *            字符串
     * @param charsetName
     *            字符集
     * @return {String}
     */
    public static String decodeToStr(String value, String charsetName) {
        byte[] decodedValue = delegate.decode(value);
        return new String(decodedValue, Charset.forName(charsetName));
    }

    private static boolean isPresent(String className, ClassLoader classLoader) {
        try {
            Class.forName(className, true, classLoader);
            return true;
        } catch (Throwable ex) {
            return false;
        }
    }

    static interface IBase64 {
        public String encode(byte[] value);

        public byte[] decode(String value);
    }

    static class Java8Base64 implements IBase64 {
        @Override
        public String encode(byte[] value) {
            return java.util.Base64.getEncoder().encodeToString(value);
        }

        @Override
        public byte[] decode(String value) {
            return java.util.Base64.getDecoder().decode(value);
        }
    }

    static class Java67Base64 implements IBase64 {
        public String encode(byte[] data) {
            return javax.xml.bind.DatatypeConverter.printBase64Binary(data);
        }

        public byte[] decode(String base64) {
            return javax.xml.bind.DatatypeConverter.parseBase64Binary(base64);
        }
    }
}