/**
    * Copyright The Apache Software Foundation
    *
    * 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.bucket;
  
  import static org.junit.Assert.assertArrayEquals;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotEquals;
  import static org.junit.Assert.assertNotNull;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.junit.After;
  import org.junit.Before;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  /**
   * Basic test for {@link FileIOEngine}
   */
  @Category(SmallTests.class)
  public class TestFileIOEngine {
  
    private static final long TOTAL_CAPACITY = 6 * 1024 * 1024; // 6 MB
    private static final String[] FILE_PATHS = {"testFileIOEngine1", "testFileIOEngine2",
        "testFileIOEngine3"};
    private static final long SIZE_PER_FILE = TOTAL_CAPACITY / FILE_PATHS.length; // 2 MB per File
    private final static List<Long> boundaryStartPositions = new ArrayList<Long>();
    private final static List<Long> boundaryStopPositions = new ArrayList<Long>();
  
    private FileIOEngine fileIOEngine;
  
    static {
      boundaryStartPositions.add(0L);
      for (int i = 1; i < FILE_PATHS.length; i++) {
        boundaryStartPositions.add(SIZE_PER_FILE * i - 1);
        boundaryStartPositions.add(SIZE_PER_FILE * i);
        boundaryStartPositions.add(SIZE_PER_FILE * i + 1);
      }
      for (int i = 1; i < FILE_PATHS.length; i++) {
        boundaryStopPositions.add(SIZE_PER_FILE * i - 1);
        boundaryStopPositions.add(SIZE_PER_FILE * i);
        boundaryStopPositions.add(SIZE_PER_FILE * i + 1);
      }
      boundaryStopPositions.add(SIZE_PER_FILE * FILE_PATHS.length - 1);
    }
  
    @Before
    public void setUp() throws IOException {
      fileIOEngine = new FileIOEngine(TOTAL_CAPACITY, FILE_PATHS);
    }
  
    @After
    public void cleanUp() throws IOException {
      fileIOEngine.shutdown();
      for (String filePath : FILE_PATHS) {
        File file = new File(filePath);
        if (file.exists()) {
          file.delete();
        }
      }
    }
  
    @Test
    public void testFileIOEngine() throws IOException {
      for (int i = 0; i < 500; i++) {
        int len = (int) Math.floor(Math.random() * 100) + 1;
        long offset = (long) Math.floor(Math.random() * TOTAL_CAPACITY % (TOTAL_CAPACITY - len));
        if (i < boundaryStartPositions.size()) {
          // make the boundary start positon
          offset = boundaryStartPositions.get(i);
        } else if ((i - boundaryStartPositions.size()) < boundaryStopPositions.size()) {
          // make the boundary stop positon
          offset = boundaryStopPositions.get(i - boundaryStartPositions.size()) - len + 1;
        } else if (i % 2 == 0) {
          // make the cross-files block writing/reading
          offset = Math.max(1, i % FILE_PATHS.length) * SIZE_PER_FILE - len / 2;
        }
       byte[] data1 = new byte[len];
       for (int j = 0; j < data1.length; ++j) {
         data1[j] = (byte) (Math.random() * 255);
       }
       byte[] data2 = new byte[len];
       fileIOEngine.write(ByteBuffer.wrap(data1), offset);
       fileIOEngine.read(ByteBuffer.wrap(data2), offset);
       assertArrayEquals(data1, data2);
     }
   }
 
   @Test
   public void testFileIOEngineHandlesZeroLengthInput() throws IOException {
     byte[] data1 = new byte[0];
 
 
     byte[] data2 = new byte[0];
     fileIOEngine.write(ByteBuffer.wrap(data1), 0);
     fileIOEngine.read(ByteBuffer.wrap(data2), 0);
     assertArrayEquals(data1, data2);
   }
 
   @Test
   public void testClosedChannelException() throws IOException {
     fileIOEngine.closeFileChannels();
     int len = 5;
     long offset = 0L;
     byte[] data1 = new byte[len];
     for (int j = 0; j < data1.length; ++j) {
       data1[j] = (byte) (Math.random() * 255);
     }
     byte[] data2 = new byte[len];
     fileIOEngine.write(ByteBuffer.wrap(data1), offset);
     fileIOEngine.read(ByteBuffer.wrap(data2), offset);
     assertArrayEquals(data1, data2);
   }
 
   @Test
   public void testRefreshFileConnection() throws IOException {
     FileChannel[] fileChannels = fileIOEngine.getFileChannels();
     FileChannel fileChannel = fileChannels[0];
     assertNotNull(fileChannel);
     fileChannel.close();
     fileIOEngine.refreshFileConnection(0, new IOException("Test Exception"));
     FileChannel[] reopenedFileChannels = fileIOEngine.getFileChannels();
     FileChannel reopenedFileChannel = reopenedFileChannels[0];
     assertNotEquals(fileChannel, reopenedFileChannel);
     assertEquals(fileChannels.length, reopenedFileChannels.length);
     for (int i = 1; i < fileChannels.length; i++) {
       assertEquals(fileChannels[i], reopenedFileChannels[i]);
     }
   }
 }