import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.IntStream;

public final class Chunker implements IChunker{
    private static final int CHUNK_SIZE = 512;
    private static final byte[] KEY_WORD =
            new byte[]{34, 36, 83, 84, 79, 80, 95, 84, 82, 65, 78, 83, 70, 69, 82, 82, 73, 78, 71, 36, 34};

    /**
     * This method is used to convert inputArray to a list of chunks, and added
     * key word to the end.
     *
     * @param inputArray
     * @return List of chunks
     */
    @Override
    public List<byte[]> split(byte[] inputArray) {
        List<byte[]> chunks = new ArrayList<>();

        for (int index = 0; index < inputArray.length; index += CHUNK_SIZE) {
            if (inputArray.length - index < CHUNK_SIZE) {
                chunks.add(Arrays.copyOfRange(inputArray, index, inputArray.length - (CHUNK_SIZE * index + 1)));
                break;
            }

            chunks.add(Arrays.copyOfRange(inputArray, index, index + CHUNK_SIZE - 1));
        }

        chunks.add(getKeyWord());

        return chunks;
    }

    /**
     * This method is used to get "stop chunk", which shows us
     * end of transferring query to server.
     *
     * @return KEY_WORD
     */
    @Override
    public byte[] getKeyWord() {
        byte[] stopChunk = new byte[CHUNK_SIZE];
        for (int index = 0; index < KEY_WORD.length; index++) {
            stopChunk[index] = KEY_WORD[index];
        }
        return stopChunk;
    }

    /**
     * This method joins all chunks to one array.
     *
     * @param chunks
     * @return outputArray
     */
    @Override
    public byte[] join(List<byte[]> chunks) {
        chunks.remove(chunks.size() - 1);

        byte[] outputArray = new byte[CHUNK_SIZE * chunks.size()];

        for (int iteration = 0; iteration < chunks.size(); iteration++) {
            for (int index = 0; index < CHUNK_SIZE; index++) {
                outputArray[index + iteration * CHUNK_SIZE] = chunks.get(iteration)[index];
            }
        }

        return outputArray;
    }

    public static void main(String[] args) {

    }
}