/*
 * 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.regionserver.wal;

import static org.apache.hadoop.hbase.regionserver.wal.AbstractProtobufWALReader.DEFAULT_WAL_TRAILER_WARN_SIZE;
import static org.apache.hadoop.hbase.regionserver.wal.AbstractProtobufWALReader.PB_WAL_COMPLETE_MAGIC;
import static org.apache.hadoop.hbase.regionserver.wal.AbstractProtobufWALReader.PB_WAL_MAGIC;
import static org.apache.hadoop.hbase.regionserver.wal.AbstractProtobufWALReader.WAL_TRAILER_WARN_SIZE;

import java.io.IOException;
import java.io.OutputStream;
import java.security.Key;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.codec.Codec;
import org.apache.hadoop.hbase.io.asyncfs.monitor.StreamSlowMonitor;
import org.apache.hadoop.hbase.io.compress.Compression;
import org.apache.hadoop.hbase.io.crypto.Cipher;
import org.apache.hadoop.hbase.io.crypto.Encryption;
import org.apache.hadoop.hbase.io.crypto.Encryptor;
import org.apache.hadoop.hbase.io.util.LRUDictionary;
import org.apache.hadoop.hbase.security.EncryptionUtil;
import org.apache.hadoop.hbase.security.User;
import org.apache.hadoop.hbase.util.CommonFSUtils;
import org.apache.hadoop.hbase.util.CommonFSUtils.StreamLacksCapabilityException;
import org.apache.hadoop.hbase.util.EncryptionTest;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.hbase.thirdparty.com.google.protobuf.UnsafeByteOperations;

import org.apache.hadoop.hbase.shaded.protobuf.generated.WALProtos.WALHeader;
import org.apache.hadoop.hbase.shaded.protobuf.generated.WALProtos.WALTrailer;

/**
 * Base class for Protobuf log writer.
 */
@InterfaceAudience.Private
public abstract class AbstractProtobufLogWriter {

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

  protected CompressionContext compressionContext;
  protected Configuration conf;
  protected Encryptor encryptor;
  protected Codec.Encoder cellEncoder;
  protected WALCellCodec.ByteStringCompressor compressor;
  protected boolean trailerWritten;
  protected WALTrailer trailer;
  // maximum size of the wal Trailer in bytes. If a user writes/reads a trailer with size larger
  // than this size, it is written/read respectively, with a WARN message in the log.
  protected int trailerWarnSize;

  protected AtomicLong length = new AtomicLong();

  private WALCellCodec getCodec(Configuration conf, CompressionContext compressionContext)
    throws IOException {
    return WALCellCodec.create(conf, null, compressionContext);
  }

  private WALHeader buildWALHeader(Configuration conf, WALHeader.Builder builder)
    throws IOException {
    builder.setWriterClsName(getWriterClassName());
    builder.setCellCodecClsName(WALCellCodec.getWALCellCodecClass(conf).getName());
    return builder.build();
  }

  private WALHeader buildSecureWALHeader(Configuration conf, WALHeader.Builder builder)
    throws IOException {
    EncryptionTest.testKeyProvider(conf);
    EncryptionTest.testCipherProvider(conf);

    // Get an instance of our cipher
    final String cipherName =
      conf.get(HConstants.CRYPTO_WAL_ALGORITHM_CONF_KEY, HConstants.CIPHER_AES);
    Cipher cipher = Encryption.getCipher(conf, cipherName);
    if (cipher == null) {
      throw new RuntimeException("Cipher '" + cipherName + "' is not available");
    }

    // Generate a random encryption key for this WAL
    Key key = cipher.getRandomKey();
    builder.setEncryptionKey(UnsafeByteOperations.unsafeWrap(EncryptionUtil.wrapKey(conf,
      conf.get(HConstants.CRYPTO_WAL_KEY_NAME_CONF_KEY,
        conf.get(HConstants.CRYPTO_MASTERKEY_NAME_CONF_KEY, User.getCurrent().getShortName())),
      key)));

    // Set up the encryptor
    Encryptor encryptor = cipher.getEncryptor();
    encryptor.setKey(key);
    this.encryptor = encryptor;
    if (LOG.isTraceEnabled()) {
      LOG.trace("Initialized secure protobuf WAL: cipher={}", cipher.getName());
    }
    builder.setWriterClsName(getWriterClassName());
    builder.setCellCodecClsName(SecureWALCellCodec.class.getName());
    return builder.build();
  }

  private String getWriterClassName() {
    // class name which is recognized by hbase-1.x to avoid ProtobufLogReader throwing error:
    // IOException: Got unknown writer class: AsyncProtobufLogWriter
    if (encryptor == null) {
      return "ProtobufLogWriter";
    } else {
      return "SecureProtobufLogWriter";
    }
  }

  private boolean initializeCompressionContext(Configuration conf, Path path) throws IOException {
    boolean doCompress = conf.getBoolean(HConstants.ENABLE_WAL_COMPRESSION, false);
    if (doCompress) {
      try {
        final boolean useTagCompression =
          conf.getBoolean(CompressionContext.ENABLE_WAL_TAGS_COMPRESSION, true);
        final boolean useValueCompression =
          conf.getBoolean(CompressionContext.ENABLE_WAL_VALUE_COMPRESSION, false);
        final Compression.Algorithm valueCompressionType = useValueCompression
          ? CompressionContext.getValueCompressionAlgorithm(conf)
          : Compression.Algorithm.NONE;
        if (LOG.isTraceEnabled()) {
          LOG.trace(
            "Initializing compression context for {}: isRecoveredEdits={}"
              + ", hasTagCompression={}, hasValueCompression={}, valueCompressionType={}",
            path, CommonFSUtils.isRecoveredEdits(path), useTagCompression, useValueCompression,
            valueCompressionType);
        }
        this.compressionContext =
          new CompressionContext(LRUDictionary.class, CommonFSUtils.isRecoveredEdits(path),
            useTagCompression, useValueCompression, valueCompressionType);
      } catch (Exception e) {
        throw new IOException("Failed to initiate CompressionContext", e);
      }
    }
    return doCompress;
  }

  public void init(FileSystem fs, Path path, Configuration conf, boolean overwritable,
    long blocksize, StreamSlowMonitor monitor) throws IOException, StreamLacksCapabilityException {
    try {
      this.conf = conf;
      boolean doCompress = initializeCompressionContext(conf, path);
      this.trailerWarnSize = conf.getInt(WAL_TRAILER_WARN_SIZE, DEFAULT_WAL_TRAILER_WARN_SIZE);
      int bufferSize = CommonFSUtils.getDefaultBufferSize(fs);
      short replication = (short) conf.getInt("hbase.regionserver.hlog.replication",
        CommonFSUtils.getDefaultReplication(fs, path));

      initOutput(fs, path, overwritable, bufferSize, replication, blocksize, monitor);

      boolean doTagCompress =
        doCompress && conf.getBoolean(CompressionContext.ENABLE_WAL_TAGS_COMPRESSION, true);
      boolean doValueCompress =
        doCompress && conf.getBoolean(CompressionContext.ENABLE_WAL_VALUE_COMPRESSION, false);
      WALHeader.Builder headerBuilder = WALHeader.newBuilder().setHasCompression(doCompress)
        .setHasTagCompression(doTagCompress).setHasValueCompression(doValueCompress);
      if (doValueCompress) {
        headerBuilder.setValueCompressionAlgorithm(
          CompressionContext.getValueCompressionAlgorithm(conf).ordinal());
      }
      if (conf.getBoolean(HConstants.ENABLE_WAL_ENCRYPTION, false)) {
        length.set(writeMagicAndWALHeader(PB_WAL_MAGIC, buildSecureWALHeader(conf, headerBuilder)));
        secureInitAfterHeader(doCompress, encryptor);
      } else {
        length.set(writeMagicAndWALHeader(PB_WAL_MAGIC, buildWALHeader(conf, headerBuilder)));
        initAfterHeader(doCompress);
      }

      // instantiate trailer to default value.
      trailer = WALTrailer.newBuilder().build();

      if (LOG.isTraceEnabled()) {
        LOG.trace("Initialized protobuf WAL={}, compression={}, tagCompression={}"
          + ", valueCompression={}", path, doCompress, doTagCompress, doValueCompress);
      }
    } catch (Exception e) {
      LOG.warn("Init output failed, path={}", path, e);
      closeOutputIfNecessary();
      throw e;
    }
  }

  private void initAfterHeader(boolean doCompress) throws IOException {
    WALCellCodec codec = getCodec(conf, this.compressionContext);
    this.cellEncoder = codec.getEncoder(getOutputStreamForCellEncoder());
    if (doCompress) {
      this.compressor = codec.getByteStringCompressor();
    } else {
      this.compressor = WALCellCodec.getNoneCompressor();
    }
  }

  private void secureInitAfterHeader(boolean doCompress, Encryptor encryptor) throws IOException {
    if (encryptor != null) {
      WALCellCodec codec = SecureWALCellCodec.getCodec(this.conf, encryptor);
      this.cellEncoder = codec.getEncoder(getOutputStreamForCellEncoder());
      // We do not support compression
      this.compressionContext = null;
      this.compressor = WALCellCodec.getNoneCompressor();
    } else {
      initAfterHeader(doCompress);
    }
  }

  void setWALTrailer(WALTrailer walTrailer) {
    this.trailer = walTrailer;
  }

  public long getLength() {
    return length.get();
  }

  private WALTrailer buildWALTrailer(WALTrailer.Builder builder) {
    return builder.build();
  }

  protected final void writeWALTrailer() {
    try {
      int trailerSize = 0;
      if (this.trailer == null) {
        // use default trailer.
        LOG.warn("WALTrailer is null. Continuing with default.");
        this.trailer = buildWALTrailer(WALTrailer.newBuilder());
        trailerSize = this.trailer.getSerializedSize();
      } else if ((trailerSize = this.trailer.getSerializedSize()) > this.trailerWarnSize) {
        // continue writing after warning the user.
        LOG.warn("Please investigate WALTrailer usage. Trailer size > maximum size : " + trailerSize
          + " > " + this.trailerWarnSize);
      }
      length.set(writeWALTrailerAndMagic(trailer, PB_WAL_COMPLETE_MAGIC));
      this.trailerWritten = true;
    } catch (IOException ioe) {
      LOG.warn("Failed to write trailer, non-fatal, continuing...", ioe);
    }
  }

  protected abstract void initOutput(FileSystem fs, Path path, boolean overwritable, int bufferSize,
    short replication, long blockSize, StreamSlowMonitor monitor)
    throws IOException, StreamLacksCapabilityException;

  /**
   * It is straight forward to close the output, do not need to write trailer like the Writer.close
   */
  protected void closeOutputIfNecessary() {
  }

  /**
   * return the file length after written.
   */
  protected abstract long writeMagicAndWALHeader(byte[] magic, WALHeader header) throws IOException;

  protected abstract long writeWALTrailerAndMagic(WALTrailer trailer, byte[] magic)
    throws IOException;

  protected abstract OutputStream getOutputStreamForCellEncoder();
}
