/*
 * 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.hadoop.hbase.io.hfile;

import static org.apache.hadoop.hbase.io.compress.Compression.Algorithm.GZ;
import static org.apache.hadoop.hbase.io.compress.Compression.Algorithm.NONE;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseTestingUtil;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.fs.HFileSystem;
import org.apache.hadoop.hbase.io.ByteBuffAllocator;
import org.apache.hadoop.hbase.io.FSDataInputStreamWrapper;
import org.apache.hadoop.hbase.io.compress.Compression;
import org.apache.hadoop.hbase.nio.ByteBuff;
import org.apache.hadoop.hbase.nio.MultiByteBuff;
import org.apache.hadoop.hbase.nio.SingleByteBuff;
import org.apache.hadoop.hbase.testclassification.IOTests;
import org.apache.hadoop.hbase.testclassification.SmallTests;
import org.apache.hadoop.hbase.util.ChecksumType;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Tag(IOTests.TAG)
@Tag(SmallTests.TAG)
public class TestChecksum {

  private static final Logger LOG = LoggerFactory.getLogger(TestChecksum.class);

  static final Compression.Algorithm[] COMPRESSION_ALGORITHMS = { NONE, GZ };

  static final int[] BYTES_PER_CHECKSUM = { 50, 500, 688, 16 * 1024, (16 * 1024 + 980), 64 * 1024 };

  private static final HBaseTestingUtil TEST_UTIL = new HBaseTestingUtil();
  private FileSystem fs;
  private HFileSystem hfs;

  @BeforeEach
  public void setUp() throws Exception {
    fs = HFileSystem.get(TEST_UTIL.getConfiguration());
    hfs = (HFileSystem) fs;
  }

  @Test
  public void testNewBlocksHaveDefaultChecksum() throws IOException {
    Path path = new Path(TEST_UTIL.getDataTestDir(), "default_checksum");
    FSDataOutputStream os = fs.create(path);
    HFileContext meta = new HFileContextBuilder().build();
    HFileBlock.Writer hbw = new HFileBlock.Writer(TEST_UTIL.getConfiguration(), null, meta);
    DataOutputStream dos = hbw.startWriting(BlockType.DATA);
    for (int i = 0; i < 1000; ++i)
      dos.writeInt(i);
    hbw.writeHeaderAndData(os);
    int totalSize = hbw.getOnDiskSizeWithHeader();
    os.close();

    // Use hbase checksums.
    assertEquals(true, hfs.useHBaseChecksum());

    FSDataInputStreamWrapper is = new FSDataInputStreamWrapper(fs, path);
    meta = new HFileContextBuilder().withHBaseCheckSum(true).build();
    ReaderContext context = new ReaderContextBuilder().withInputStreamWrapper(is)
      .withFileSize(totalSize).withFileSystem((HFileSystem) fs).withFilePath(path).build();
    HFileBlock.FSReader hbr = new HFileBlock.FSReaderImpl(context, meta, ByteBuffAllocator.HEAP,
      TEST_UTIL.getConfiguration());
    HFileBlock b = hbr.readBlockData(0, -1, false, false, true);
    assertTrue(!b.isSharedMem());
    assertEquals(b.getChecksumType(), ChecksumType.getDefaultChecksumType().getCode());
  }

  private void verifyMBBCheckSum(ByteBuff buf) throws IOException {
    int size = buf.remaining() / 2 + 1;
    ByteBuff mbb = new MultiByteBuff(ByteBuffer.allocate(size), ByteBuffer.allocate(size))
      .position(0).limit(buf.remaining());
    for (int i = buf.position(); i < buf.limit(); i++) {
      mbb.put(buf.get(i));
    }
    mbb.position(0).limit(buf.remaining());
    assertEquals(mbb.remaining(), buf.remaining());
    assertTrue(mbb.remaining() > size);
    ChecksumUtil.validateChecksum(mbb, "test", 0, HConstants.HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM);
  }

  private void verifySBBCheckSum(ByteBuff buf) throws IOException {
    ChecksumUtil.validateChecksum(buf, "test", 0, HConstants.HFILEBLOCK_HEADER_SIZE_NO_CHECKSUM);
  }

  @Test
  public void testVerifyCheckSum() throws IOException {
    int intCount = 10000;
    for (ChecksumType ckt : ChecksumType.values()) {
      Path path = new Path(TEST_UTIL.getDataTestDir(), "checksum" + ckt.getName());
      FSDataOutputStream os = fs.create(path);
      HFileContext meta = new HFileContextBuilder().withChecksumType(ckt).build();
      HFileBlock.Writer hbw = new HFileBlock.Writer(TEST_UTIL.getConfiguration(), null, meta);
      DataOutputStream dos = hbw.startWriting(BlockType.DATA);
      for (int i = 0; i < intCount; ++i) {
        dos.writeInt(i);
      }
      hbw.writeHeaderAndData(os);
      int totalSize = hbw.getOnDiskSizeWithHeader();
      os.close();

      // Use hbase checksums.
      assertEquals(true, hfs.useHBaseChecksum());

      FSDataInputStreamWrapper is = new FSDataInputStreamWrapper(fs, path);
      meta = new HFileContextBuilder().withHBaseCheckSum(true).build();
      ReaderContext context = new ReaderContextBuilder().withInputStreamWrapper(is)
        .withFileSize(totalSize).withFileSystem((HFileSystem) fs).withFilePath(path).build();
      HFileBlock.FSReader hbr = new HFileBlock.FSReaderImpl(context, meta, ByteBuffAllocator.HEAP,
        TEST_UTIL.getConfiguration());
      HFileBlock b = hbr.readBlockData(0, -1, false, false, true);
      assertTrue(!b.isSharedMem());

      ByteBuff bufferWithChecksum = getBufferWithChecksum(b);

      // verify SingleByteBuff checksum.
      verifySBBCheckSum(bufferWithChecksum);

      // verify MultiByteBuff checksum.
      verifyMBBCheckSum(bufferWithChecksum);

      ByteBuff data = b.getBufferWithoutHeader();
      for (int i = 0; i < intCount; i++) {
        assertEquals(i, data.getInt());
      }
      try {
        data.getInt();
        fail();
      } catch (BufferUnderflowException e) {
        // expected failure
      }
      assertEquals(0, HFile.getAndResetChecksumFailuresCount());
    }
  }

  /**
   * HFileBlock buffer does not include checksum because it is discarded after verifying upon
   * reading from disk. We artificially add a checksum onto the buffer for use in testing that
   * ChecksumUtil.validateChecksum works for SingleByteBuff and MultiByteBuff in
   * {@link #verifySBBCheckSum(ByteBuff)} and {@link #verifyMBBCheckSum(ByteBuff)}
   */
  private ByteBuff getBufferWithChecksum(HFileBlock block) throws IOException {
    ByteBuff buf = block.getBufferReadOnly();

    int numBytes =
      (int) ChecksumUtil.numBytes(buf.remaining(), block.getHFileContext().getBytesPerChecksum());
    byte[] checksum = new byte[numBytes];
    ChecksumUtil.generateChecksums(buf.array(), 0, buf.limit(), checksum, 0,
      block.getHFileContext().getChecksumType(), block.getBytesPerChecksum());

    ByteBuff bufWithChecksum = ByteBuffAllocator.HEAP.allocate(buf.limit() + numBytes);
    bufWithChecksum.put(buf.array(), 0, buf.limit());
    bufWithChecksum.put(checksum);

    return bufWithChecksum.rewind();
  }

  /**
   * Introduce checksum failures and check that we can still read the data
   */
  @Test
  public void testChecksumCorruption() throws IOException {
    testChecksumCorruptionInternals(false);
    testChecksumCorruptionInternals(true);
  }

  protected void testChecksumCorruptionInternals(boolean useTags) throws IOException {
    for (Compression.Algorithm algo : COMPRESSION_ALGORITHMS) {
      for (boolean pread : new boolean[] { false, true }) {
        LOG.info("testChecksumCorruption: Compression algorithm: " + algo + ", pread=" + pread);
        Path path = new Path(TEST_UTIL.getDataTestDir(), "blocks_v2_" + algo);
        FSDataOutputStream os = fs.create(path);
        HFileContext meta = new HFileContextBuilder().withCompression(algo).withIncludesMvcc(true)
          .withIncludesTags(useTags).withBytesPerCheckSum(HFile.DEFAULT_BYTES_PER_CHECKSUM).build();
        HFileBlock.Writer hbw = new HFileBlock.Writer(TEST_UTIL.getConfiguration(), null, meta);
        long totalSize = 0;
        for (int blockId = 0; blockId < 2; ++blockId) {
          DataOutputStream dos = hbw.startWriting(BlockType.DATA);
          for (int i = 0; i < 1234; ++i)
            dos.writeInt(i);
          hbw.writeHeaderAndData(os);
          totalSize += hbw.getOnDiskSizeWithHeader();
        }
        os.close();

        // Use hbase checksums.
        assertEquals(true, hfs.useHBaseChecksum());

        // Do a read that purposely introduces checksum verification failures.
        FSDataInputStreamWrapper is = new FSDataInputStreamWrapper(fs, path);
        meta = new HFileContextBuilder().withCompression(algo).withIncludesMvcc(true)
          .withIncludesTags(useTags).withHBaseCheckSum(true).build();
        ReaderContext context = new ReaderContextBuilder().withInputStreamWrapper(is)
          .withFileSize(totalSize).withFileSystem(fs).withFilePath(path).build();
        HFileBlock.FSReader hbr =
          new CorruptedFSReaderImpl(context, meta, TEST_UTIL.getConfiguration());
        HFileBlock b = hbr.readBlockData(0, -1, pread, false, true);
        b.sanityCheck();
        assertEquals(4936, b.getUncompressedSizeWithoutHeader());
        assertEquals(algo == GZ ? 2173 : 4936,
          b.getOnDiskSizeWithoutHeader() - b.totalChecksumBytes());
        // read data back from the hfile, exclude header and checksum
        ByteBuff bb = b.unpack(meta, hbr).getBufferWithoutHeader(); // read back data
        DataInputStream in =
          new DataInputStream(new ByteArrayInputStream(bb.array(), bb.arrayOffset(), bb.limit()));

        // assert that we encountered hbase checksum verification failures
        // but still used hdfs checksums and read data successfully.
        assertEquals(1, HFile.getAndResetChecksumFailuresCount());
        validateData(in);

        // A single instance of hbase checksum failure causes the reader to
        // switch off hbase checksum verification for the next 100 read
        // requests. Verify that this is correct.
        for (int i = 0; i < HFileBlock.CHECKSUM_VERIFICATION_NUM_IO_THRESHOLD + 1; i++) {
          b = hbr.readBlockData(0, -1, pread, false, true);
          assertTrue(b.getBufferReadOnly() instanceof SingleByteBuff);
          assertEquals(0, HFile.getAndResetChecksumFailuresCount());
        }
        // The next read should have hbase checksum verification reanabled,
        // we verify this by assertng that there was a hbase-checksum failure.
        b = hbr.readBlockData(0, -1, pread, false, true);
        assertTrue(b.getBufferReadOnly() instanceof SingleByteBuff);
        assertEquals(1, HFile.getAndResetChecksumFailuresCount());

        // Since the above encountered a checksum failure, we switch
        // back to not checking hbase checksums.
        b = hbr.readBlockData(0, -1, pread, false, true);
        assertTrue(b.getBufferReadOnly() instanceof SingleByteBuff);
        assertEquals(0, HFile.getAndResetChecksumFailuresCount());
        is.close();

        // Now, use a completely new reader. Switch off hbase checksums in
        // the configuration. In this case, we should not detect
        // any retries within hbase.
        Configuration conf = TEST_UTIL.getConfiguration();
        HFileSystem newfs = new HFileSystem(conf, false);
        assertEquals(false, newfs.useHBaseChecksum());
        is = new FSDataInputStreamWrapper(newfs, path);
        context = new ReaderContextBuilder().withInputStreamWrapper(is).withFileSize(totalSize)
          .withFileSystem(newfs).withFilePath(path).build();
        hbr = new CorruptedFSReaderImpl(context, meta, conf);
        b = hbr.readBlockData(0, -1, pread, false, true);
        is.close();
        b.sanityCheck();
        b = b.unpack(meta, hbr);
        assertEquals(4936, b.getUncompressedSizeWithoutHeader());
        assertEquals(algo == GZ ? 2173 : 4936,
          b.getOnDiskSizeWithoutHeader() - b.totalChecksumBytes());
        // read data back from the hfile, exclude header and checksum
        bb = b.getBufferWithoutHeader(); // read back data
        in =
          new DataInputStream(new ByteArrayInputStream(bb.array(), bb.arrayOffset(), bb.limit()));

        // assert that we did not encounter hbase checksum verification failures
        // but still used hdfs checksums and read data successfully.
        assertEquals(0, HFile.getAndResetChecksumFailuresCount());
        validateData(in);
      }
    }
  }

  /**
   * Test different values of bytesPerChecksum
   */
  @Test
  public void testChecksumChunks() throws IOException {
    testChecksumInternals(false);
    testChecksumInternals(true);
  }

  protected void testChecksumInternals(boolean useTags) throws IOException {
    Compression.Algorithm algo = NONE;
    for (boolean pread : new boolean[] { false, true }) {
      for (int bytesPerChecksum : BYTES_PER_CHECKSUM) {
        Path path =
          new Path(TEST_UTIL.getDataTestDir(), "checksumChunk_" + algo + bytesPerChecksum);
        FSDataOutputStream os = fs.create(path);
        HFileContext meta = new HFileContextBuilder().withCompression(algo).withIncludesMvcc(true)
          .withIncludesTags(useTags).withHBaseCheckSum(true).withBytesPerCheckSum(bytesPerChecksum)
          .build();
        HFileBlock.Writer hbw = new HFileBlock.Writer(TEST_UTIL.getConfiguration(), null, meta);

        // write one block. The block has data
        // that is at least 6 times more than the checksum chunk size
        long dataSize = 0;
        DataOutputStream dos = hbw.startWriting(BlockType.DATA);
        for (; dataSize < 6 * bytesPerChecksum;) {
          for (int i = 0; i < 1234; ++i) {
            dos.writeInt(i);
            dataSize += 4;
          }
        }
        hbw.writeHeaderAndData(os);
        long totalSize = hbw.getOnDiskSizeWithHeader();
        os.close();

        long expectedChunks =
          ChecksumUtil.numChunks(dataSize + HConstants.HFILEBLOCK_HEADER_SIZE, bytesPerChecksum);
        LOG.info(
          "testChecksumChunks: pread={}, bytesPerChecksum={}, fileSize={}, "
            + "dataSize={}, expectedChunks={}, compression={}",
          pread, bytesPerChecksum, totalSize, dataSize, expectedChunks, algo.toString());

        // Verify hbase checksums.
        assertEquals(true, hfs.useHBaseChecksum());

        // Read data back from file.
        FSDataInputStream is = fs.open(path);
        FSDataInputStream nochecksum = hfs.getNoChecksumFs().open(path);
        meta = new HFileContextBuilder().withCompression(algo).withIncludesMvcc(true)
          .withIncludesTags(useTags).withHBaseCheckSum(true).withBytesPerCheckSum(bytesPerChecksum)
          .build();
        ReaderContext context = new ReaderContextBuilder()
          .withInputStreamWrapper(new FSDataInputStreamWrapper(is, nochecksum))
          .withFileSize(totalSize).withFileSystem(hfs).withFilePath(path).build();
        HFileBlock.FSReader hbr = new HFileBlock.FSReaderImpl(context, meta, ByteBuffAllocator.HEAP,
          TEST_UTIL.getConfiguration());
        HFileBlock b = hbr.readBlockData(0, -1, pread, false, true);
        assertTrue(b.getBufferReadOnly() instanceof SingleByteBuff);
        is.close();
        b.sanityCheck();
        assertEquals(dataSize, b.getUncompressedSizeWithoutHeader());

        // verify that we have the expected number of checksum chunks
        assertEquals(totalSize,
          HConstants.HFILEBLOCK_HEADER_SIZE + dataSize + expectedChunks * HFileBlock.CHECKSUM_SIZE);

        // assert that we did not encounter hbase checksum verification failures
        assertEquals(0, HFile.getAndResetChecksumFailuresCount());
      }
    }
  }

  private void validateData(DataInputStream in) throws IOException {
    // validate data
    for (int i = 0; i < 1234; i++) {
      int val = in.readInt();
      assertEquals(i, val, "testChecksumCorruption: data mismatch at index " + i);
    }
  }

  /**
   * This class is to test checksum behavior when data is corrupted. It mimics the following
   * behavior: - When fs checksum is disabled, hbase may get corrupted data from hdfs. If
   * verifyChecksum is true, it means hbase checksum is on and fs checksum is off, so we corrupt the
   * data. - When fs checksum is enabled, hdfs will get a different copy from another node, and will
   * always return correct data. So we don't corrupt the data when verifyChecksum for hbase is off.
   */
  static private class CorruptedFSReaderImpl extends HFileBlock.FSReaderImpl {
    /**
     * If set to true, corrupt reads using readAtOffset(...).
     */
    boolean corruptDataStream = false;

    public CorruptedFSReaderImpl(ReaderContext context, HFileContext meta, Configuration conf)
      throws IOException {
      super(context, meta, ByteBuffAllocator.HEAP, conf);
    }

    @Override
    protected HFileBlock readBlockDataInternal(FSDataInputStream is, long offset,
      long onDiskSizeWithHeaderL, boolean pread, boolean verifyChecksum, boolean updateMetrics,
      boolean useHeap) throws IOException {
      if (verifyChecksum) {
        corruptDataStream = true;
      }
      HFileBlock b = super.readBlockDataInternal(is, offset, onDiskSizeWithHeaderL, pread,
        verifyChecksum, updateMetrics, useHeap);
      corruptDataStream = false;
      return b;
    }

    @Override
    protected boolean readAtOffset(FSDataInputStream istream, ByteBuff dest, int size,
      boolean peekIntoNextBlock, long fileOffset, boolean pread) throws IOException {
      int destOffset = dest.position();
      boolean returnValue =
        super.readAtOffset(istream, dest, size, peekIntoNextBlock, fileOffset, pread);
      if (!corruptDataStream) {
        return returnValue;
      }
      // Corrupt 3rd character of block magic of next block's header.
      if (peekIntoNextBlock) {
        dest.put(destOffset + size + 3, (byte) 0b00000000);
      }
      // We might be reading this block's header too, corrupt it.
      dest.put(destOffset + 1, (byte) 0b00000000);
      // Corrupt non header data
      if (size > hdrSize) {
        dest.put(destOffset + hdrSize + 1, (byte) 0b00000000);
      }
      return returnValue;
    }
  }
}