/**
 * 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.server.namenode.snapshot;

import java.util.Random;

import org.apache.hadoop.fs.FileStatus;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DFSTestUtil;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.MiniDFSCluster;

public class TestSnapshotFileLength {

  private static final long SEED = 0;
  private static final short REPLICATION = 1;
  private static final int BLOCKSIZE = 1024;

  private static Configuration conf = new Configuration();
  private static MiniDFSCluster cluster;
  private static DistributedFileSystem hdfs;

  private final Path dir = new Path("/TestSnapshotFileLength");
  private final Path sub = new Path(dir, "sub1");
  private final String file1Name = "file1";
  private final String snapshot1 = "snapshot1";

  @Before
  public void setUp() throws Exception {
    cluster = new MiniDFSCluster.Builder(conf).numDataNodes(REPLICATION)
                                              .build();
    cluster.waitActive();
    hdfs = cluster.getFileSystem();
  }

  @After
  public void tearDown() throws Exception {
    if (cluster != null) {
      cluster.shutdown();
      cluster = null;
    }
  }


  /**
   * Test that we cannot read a file beyond its snapshot length
   * when accessing it via a snapshot path.
   *
   */
  @Test (timeout=300000)
  public void testSnapshotfileLength() throws Exception {
    hdfs.mkdirs(sub);

    int bytesRead;
    byte[] buffer = new byte[BLOCKSIZE * 8];
    FSDataInputStream fis = null;
    FileStatus fileStatus = null;

    // Create and write a file.
    Path file1 = new Path(sub, file1Name);
    DFSTestUtil.createFile(hdfs, file1, 0, REPLICATION, SEED);
    DFSTestUtil.appendFile(hdfs, file1, BLOCKSIZE);

    // Create a snapshot on the parent directory.
    hdfs.allowSnapshot(sub);
    hdfs.createSnapshot(sub, snapshot1);

    // Write more data to the file.
    DFSTestUtil.appendFile(hdfs, file1, BLOCKSIZE);

    // Make sure we can read the entire file via its non-snapshot path.
    fileStatus = hdfs.getFileStatus(file1);
    assertThat(fileStatus.getLen(), is((long) BLOCKSIZE * 2));
    fis = hdfs.open(file1);
    bytesRead = fis.read(0, buffer, 0, buffer.length);
    assertThat(bytesRead, is(BLOCKSIZE * 2));
    fis.close();

    // Try to open the file via its snapshot path.
    Path file1snap1 =
        SnapshotTestHelper.getSnapshotPath(sub, snapshot1, file1Name);
    fis = hdfs.open(file1snap1);
    fileStatus = hdfs.getFileStatus(file1snap1);
    assertThat(fileStatus.getLen(), is((long) BLOCKSIZE));

    // Make sure we can only read up to the snapshot length.
    bytesRead = fis.read(0, buffer, 0, buffer.length);
    assertThat(bytesRead, is(BLOCKSIZE));
    fis.close();
  }
}