/**
 * 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.hdfs;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSClient.Conf;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferEncryptor;
import org.apache.hadoop.hdfs.protocol.datatransfer.IOStreamPair;
import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.token.Token;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;


/**
 * Utility class to create BlockReader implementations.
 */
@InterfaceAudience.Private
public class BlockReaderFactory {
  /**
   * @see #newBlockReader(Conf, Socket, String, ExtendedBlock, Token, long,
   * long, int, boolean, String)
   */
  public static BlockReader newBlockReader(Configuration conf, Socket sock,
      String file, ExtendedBlock block, Token<BlockTokenIdentifier> blockToken,
      long startOffset, long len, DataEncryptionKey encryptionKey)
      throws IOException {
    int bufferSize = conf.getInt(DFSConfigKeys.IO_FILE_BUFFER_SIZE_KEY,
        DFSConfigKeys.IO_FILE_BUFFER_SIZE_DEFAULT);
    return newBlockReader(new Conf(conf), sock, file, block, blockToken,
        startOffset, len, bufferSize, true, "", encryptionKey, null);
  }

  /**
   * Create a new BlockReader specifically to satisfy a read.
   * This method also sends the OP_READ_BLOCK request.
   *
   * @param conf
   *     the DFSClient configuration
   * @param sock
   *     An established Socket to the DN. The BlockReader will not close it
   *     normally
   * @param file
   *     File location
   * @param block
   *     The block object
   * @param blockToken
   *     The block token for security
   * @param startOffset
   *     The read offset, relative to block head
   * @param len
   *     The number of bytes to read
   * @param bufferSize
   *     The IO buffer size (not the client buffer size)
   * @param verifyChecksum
   *     Whether to verify checksum
   * @param clientName
   *     Client name
   * @return New BlockReader instance, or null on error.
   */
  @SuppressWarnings("deprecation")
  public static BlockReader newBlockReader(Conf conf, Socket sock, String file,
      ExtendedBlock block, Token<BlockTokenIdentifier> blockToken,
      long startOffset, long len, int bufferSize, boolean verifyChecksum,
      String clientName, DataEncryptionKey encryptionKey,
      IOStreamPair ioStreams) throws IOException {
    
    if (conf.useLegacyBlockReader) {
      if (encryptionKey != null) {
        throw new RuntimeException(
            "Encryption is not supported with the legacy block reader.");
      }
      return RemoteBlockReader
          .newBlockReader(sock, file, block, blockToken, startOffset, len,
              bufferSize, verifyChecksum, clientName);
    } else {
      if (ioStreams == null) {
        ioStreams = new IOStreamPair(NetUtils.getInputStream(sock),
            NetUtils.getOutputStream(sock, HdfsServerConstants.WRITE_TIMEOUT));
        if (encryptionKey != null) {
          IOStreamPair encryptedStreams = DataTransferEncryptor
              .getEncryptedStreams(ioStreams.out, ioStreams.in, encryptionKey);
          ioStreams = encryptedStreams;
        }
      }
      
      return RemoteBlockReader2
          .newBlockReader(sock, file, block, blockToken, startOffset, len,
              bufferSize, verifyChecksum, clientName, encryptionKey, ioStreams);
    }
  }
  
  /**
   * File name to print when accessing a block directly (from servlets)
   *
   * @param s
   *     Address of the block location
   * @param poolId
   *     Block pool ID of the block
   * @param blockId
   *     Block ID of the block
   * @return string that has a file name for debug purposes
   */
  public static String getFileName(final InetSocketAddress s,
      final String poolId, final long blockId) {
    return s.toString() + ":" + poolId + ":" + blockId;
  }
}