/****************************************************************************
 * Copyright (C) 2016-2018 Maschell
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ****************************************************************************/
package de.mas.wiiu.jnus.utils;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import lombok.extern.java.Log;

@Log
public final class StreamUtils {
    private StreamUtils() {
        // Utility class
    }

    public static byte[] getBytesFromStream(InputStream in, int size) throws IOException {
        byte[] result = new byte[size];
        byte[] buffer = new byte[0x8000];
        int totalRead = 0;
        do {
            int read = in.read(buffer);
            if (read < 0) break;
            System.arraycopy(buffer, 0, result, totalRead, read);
            totalRead += read;
        } while (totalRead < size);
        in.close();
        return result;
    }

    public static int getChunkFromStream(InputStream inputStream, byte[] output, ByteArrayBuffer overflowbuffer, int BLOCKSIZE) throws IOException {
        int bytesRead = -1;
        int inBlockBuffer = 0;
        byte[] overflowbuf = overflowbuffer.getBuffer();
        do {
            try {
                bytesRead = inputStream.read(overflowbuf, overflowbuffer.getLengthOfDataInBuffer(), overflowbuffer.getSpaceLeft());

            } catch (IOException e) {
                log.info(e.getMessage());
                if (!e.getMessage().equals("Write end dead")) {
                    throw e;
                }
                bytesRead = -1;
            }

            if (bytesRead <= 0) {
                if (overflowbuffer.getLengthOfDataInBuffer() > 0) {
                    System.arraycopy(overflowbuf, 0, output, 0, overflowbuffer.getLengthOfDataInBuffer());
                    inBlockBuffer = overflowbuffer.getLengthOfDataInBuffer();
                }

                break;
            }

            overflowbuffer.addLengthOfDataInBuffer(bytesRead);

            if (inBlockBuffer + overflowbuffer.getLengthOfDataInBuffer() > BLOCKSIZE) {
                int tooMuch = (inBlockBuffer + bytesRead) - BLOCKSIZE;
                int toRead = BLOCKSIZE - inBlockBuffer;

                System.arraycopy(overflowbuf, 0, output, inBlockBuffer, toRead);
                inBlockBuffer += toRead;

                System.arraycopy(overflowbuf, toRead, overflowbuf, 0, tooMuch);
                overflowbuffer.setLengthOfDataInBuffer(tooMuch);
            } else {
                System.arraycopy(overflowbuf, 0, output, inBlockBuffer, overflowbuffer.getLengthOfDataInBuffer());
                inBlockBuffer += overflowbuffer.getLengthOfDataInBuffer();
                overflowbuffer.resetLengthOfDataInBuffer();
            }
        } while (inBlockBuffer != BLOCKSIZE);
        return inBlockBuffer;
    }

    public static void saveInputStreamToOutputStream(InputStream inputStream, OutputStream outputStream, long filesize) throws IOException {
        try {
            saveInputStreamToOutputStreamWithHash(inputStream, outputStream, filesize, null, 0L);
        } catch (CheckSumWrongException e) {
            // Should never happen because the hash is not set. Lets print it anyway.
            e.printStackTrace();
        }
    }

    public static void saveInputStreamToOutputStreamWithHash(InputStream inputStream, OutputStream outputStream, long filesize, byte[] hash,
            long expectedSizeForHash) throws IOException, CheckSumWrongException {
        MessageDigest sha1 = null;
        if (hash != null) {
            try {
                sha1 = MessageDigest.getInstance("SHA1");
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
            }
        }

        int BUFFER_SIZE = 0x8000;
        byte[] buffer = new byte[BUFFER_SIZE];
        int read = 0;
        long totalRead = 0;
        long written = 0;
        do {
            read = inputStream.read(buffer);
            if (read < 0) {
                break;
            }
            totalRead += read;

            if (totalRead > filesize) {
                read = (int) (read - (totalRead - filesize));
            }

            outputStream.write(buffer, 0, read);
            written += read;

            if (sha1 != null) {
                sha1.update(buffer, 0, read);
            }
        } while (written < filesize);

        if (sha1 != null && hash != null) {
            long missingInHash = expectedSizeForHash - written;
            if (missingInHash > 0) {
                sha1.update(new byte[(int) missingInHash]);
            }

            byte[] calculated_hash = sha1.digest();
            byte[] expected_hash = hash;
            if (!Arrays.equals(calculated_hash, expected_hash)) {
                outputStream.close();
                inputStream.close();
                throw new CheckSumWrongException("Hash doesn't match saves output stream.", calculated_hash, expected_hash);
            }
        }

        outputStream.close();
        inputStream.close();
    }

    public static void skipExactly(InputStream in, long offset) throws IOException {
        long n = offset;
        while (n != 0) {
            long skipped = in.skip(n);
            if (skipped == 0) {
                in.close();
                throw new EOFException();
            }
            n -= skipped;
        }
    }
}