/*
    * 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.commons.compress.compressors.bzip2;
  
  import org.junit.Test;
  
  import static org.junit.Assert.assertArrayEquals;
  import static org.junit.Assert.assertEquals;
  
  public class BlockSortTest {
  
      private static final byte[] FIXTURE = { 0, 1, (byte) 252, (byte) 253, (byte) 255,
                                              (byte) 254, 3, 2, (byte) 128 };
  
      /*
        Burrows-Wheeler transform of fixture the manual way:
  
        * build the matrix
  
        0, 1, 252, 253, 255, 254, 3, 2, 128
        1, 252, 253, 255, 254, 3, 2, 128, 0
        252, 253, 255, 254, 3, 2, 128, 0, 1
        253, 255, 254, 3, 2, 128, 0, 1, 252
        255, 254, 3, 2, 128, 0, 1, 252, 253
        254, 3, 2, 128, 0, 1, 252, 253, 255
        3, 2, 128, 0, 1, 252, 253, 255, 254
        2, 128, 0, 1, 252, 253, 255, 254, 3
        128, 0, 1, 252, 253, 255, 254, 3, 2
  
        * sort it
  
        0, 1, 252, 253, 255, 254, 3, 2, 128
        1, 252, 253, 255, 254, 3, 2, 128, 0
        2, 128, 0, 1, 252, 253, 255, 254, 3
        3, 2, 128, 0, 1, 252, 253, 255, 254
        128, 0, 1, 252, 253, 255, 254, 3, 2
        252, 253, 255, 254, 3, 2, 128, 0, 1
        253, 255, 254, 3, 2, 128, 0, 1, 252
        254, 3, 2, 128, 0, 1, 252, 253, 255
        255, 254, 3, 2, 128, 0, 1, 252, 253
  
        * grab last column
  
        128, 0, 3, 254, 2, 1, 252, 255, 253
  
          and the original line has been 0
      */
  
      private static final byte[] FIXTURE_BWT = { (byte) 128, 0, 3, (byte) 254, 2, 1, 
                                                  (byte) 252, (byte) 255, (byte) 253 };
  
      private static final int[] FIXTURE_SORTED = {
          0, 1, 7, 6, 8, 2, 3, 5, 4
      };
  
      private static final byte[] FIXTURE2 = { 
          'C', 'o', 'm', 'm', 'o', 'n', 's', ' ', 'C', 'o', 'm', 'p', 'r', 'e', 's', 's', 
      };
  
      private static final byte[] FIXTURE2_BWT = {
          's', 's', ' ', 'r', 'o', 'm', 'o', 'o', 'C', 'C', 'm', 'm', 'p', 'n', 's', 'e', 
      };
  
      @Test
      public void testSortFixture() {
          DS ds = setUpFixture();
          ds.s.blockSort(ds.data, FIXTURE.length - 1);
          assertFixtureSorted(ds.data);
          assertEquals(0, ds.data.origPtr);
      }
  
      @Test
      public void testSortFixtureMainSort() {
          DS ds = setUpFixture();
          ds.s.mainSort(ds.data, FIXTURE.length - 1);
          assertFixtureSorted(ds.data);
      }
  
      @Test
      public void testSortFixtureFallbackSort() {
          DS ds = setUpFixture();
          ds.s.fallbackSort(ds.data, FIXTURE.length - 1);
          assertFixtureSorted(ds.data);
     }
 
     @Test
     public void testSortFixture2() {
         DS ds = setUpFixture2();
         ds.s.blockSort(ds.data, FIXTURE2.length - 1);
         assertFixture2Sorted(ds.data);
         assertEquals(1, ds.data.origPtr);
     }
 
     @Test
     public void testSortFixture2MainSort() {
         DS ds = setUpFixture2();
         ds.s.mainSort(ds.data, FIXTURE2.length - 1);
         assertFixture2Sorted(ds.data);
     }
 
     @Test
     public void testSortFixture2FallbackSort() {
         DS ds = setUpFixture2();
         ds.s.fallbackSort(ds.data, FIXTURE2.length - 1);
         assertFixture2Sorted(ds.data);
     }
 
     @Test
     public void testFallbackSort() {
         BZip2CompressorOutputStream.Data data = new BZip2CompressorOutputStream.Data(1);
         BlockSort s = new BlockSort(data);
         int[] fmap = new int[FIXTURE.length];
         s.fallbackSort(fmap, FIXTURE, FIXTURE.length);
         assertArrayEquals(FIXTURE_SORTED, fmap);
     }
 
     private DS setUpFixture() {
         return setUpFixture(FIXTURE);
     }
 
     private void assertFixtureSorted(BZip2CompressorOutputStream.Data data) {
         assertFixtureSorted(data, FIXTURE, FIXTURE_BWT);
     }
 
     private DS setUpFixture2() {
         return setUpFixture(FIXTURE2);
     }
 
     private void assertFixture2Sorted(BZip2CompressorOutputStream.Data data) {
         assertFixtureSorted(data, FIXTURE2, FIXTURE2_BWT);
     }
 
     private DS setUpFixture(byte[] fixture) {
         BZip2CompressorOutputStream.Data data = new BZip2CompressorOutputStream.Data(1);
         System.arraycopy(fixture, 0, data.block, 1, fixture.length);
         return new DS(data, new BlockSort(data));
     }
 
     private void assertFixtureSorted(BZip2CompressorOutputStream.Data data,
                                      byte[] fixture, byte[] fixtureBwt) {
         assertEquals(fixture[fixture.length - 1], data.block[0]);
         for (int i = 0; i < fixture.length; i++) {
             assertEquals(fixtureBwt[i], data.block[data.fmap[i]]);
         }
     }
 
     private static class DS {
         private final BZip2CompressorOutputStream.Data data;
         private final BlockSort s;
         DS(BZip2CompressorOutputStream.Data data, BlockSort s) {
             this.data = data;
             this.s = s;
         }
     }
 }