/*
 * 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.eagle.log.entity.meta;

import java.io.UnsupportedEncodingException;

import org.apache.eagle.common.ByteUtil;

/**
 * String array entity serializer and deserializer
 */
public class StringArraySerDeser implements EntitySerDeser<String[]> {

    public static final int MAX_STRING_LENGTH = 65535;
    public static final String UTF_8 = "UTF-8";

    @Override
    public String[] deserialize(byte[] bytes) {
        if (bytes == null || bytes.length < 4) {
            return null;
        }
        int offset = 0;
        // get size of int array
        final int size = ByteUtil.bytesToInt(bytes, offset);
        offset += 4;
        final String[] strings = new String[size];
        try {
            for (int i = 0; i < size; i++) {
                final int len = ByteUtil.bytesToInt(bytes, offset);
                offset += 4;
                strings[i] = new String(bytes, offset, len, UTF_8);
                offset += len;
            }
        } catch (UnsupportedEncodingException e) {
            throw new IllegalArgumentException("Invalid byte array");
        }
        return strings;
    }

    /**
     * size + str1 length + str1 + str2 length + str2 + ... 4B 4B n1B 4B n2B
     * 
     * @param obj
     * @return
     */
    @Override
    public byte[] serialize(String[] array) {
        if (array == null) {
            return null;
        }
        final int size = array.length;
        final byte[][] tmp = new byte[size][];
        int total = 4 + 4 * size;
        for (int i = 0; i < size; ++i) {
            try {
                tmp[i] = array[i].getBytes(UTF_8);
            } catch (UnsupportedEncodingException e) {
                throw new IllegalArgumentException("String doesn't support UTF-8 encoding: " + array[i]);
            }
            total += tmp[i].length;
        }
        final byte[] result = new byte[total];
        int offset = 0;
        ByteUtil.intToBytes(size, result, offset);
        offset += 4;
        for (int i = 0; i < size; ++i) {
            ByteUtil.intToBytes(tmp[i].length, result, offset);
            offset += 4;
            System.arraycopy(tmp[i], 0, result, offset, tmp[i].length);
            offset += tmp[i].length;
        }
        return result;
    }

    @Override
    public Class<String[]> type() {
        return String[].class;
    }

}