/**
    * 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.metrics.impl;
  
  import static org.junit.Assert.assertEquals;
  
  import java.util.Arrays;
  import java.util.Random;
  
  
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.junit.Assert;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  /**
   * Testcases for FastLongHistogram.
   */
  @Category(SmallTests.class)
  public class TestFastLongHistogram {
  
    private static void doTestUniform(FastLongHistogram hist) {
      long[] VALUES = { 0, 10, 20, 30, 40, 50 };
      double[] qs = new double[VALUES.length];
      for (int i = 0; i < qs.length; i++) {
        qs[i] = (double) VALUES[i] / VALUES[VALUES.length - 1];
      }
  
      for (int i = 0; i < 10; i++) {
        for (long v : VALUES) {
          hist.add(v, 1);
        }
        long[] vals = hist.getQuantiles(qs);
        System.out.println(Arrays.toString(vals));
        for (int j = 0; j < qs.length; j++) {
          Assert.assertTrue(j + "-th element org: " + VALUES[j] + ", act: " + vals[j],
            Math.abs(vals[j] - VALUES[j]) <= 10);
        }
        hist.snapshotAndReset();
      }
    }
  
    @Test
    public void testUniform() {
      FastLongHistogram hist = new FastLongHistogram(100, 0, 50);
      doTestUniform(hist);
    }
  
    @Test
    public void testAdaptionOfChange() {
      // assumes the uniform distribution
      FastLongHistogram hist = new FastLongHistogram(100, 0, 100);
  
      Random rand = new Random();
  
      for (int n = 0; n < 10; n++) {
        for (int i = 0; i < 900; i++) {
          hist.add(rand.nextInt(100), 1);
        }
  
        // add 10% outliers, this breaks the assumption, hope bin10xMax works
        for (int i = 0; i < 100; i++) {
          hist.add(1000 + rand.nextInt(100), 1);
        }
  
        long[] vals = hist.getQuantiles(new double[] { 0.25, 0.75, 0.95 });
        System.out.println(Arrays.toString(vals));
        if (n == 0) {
          Assert.assertTrue("Out of possible value", vals[0] >= 0 && vals[0] <= 50);
          Assert.assertTrue("Out of possible value", vals[1] >= 50 && vals[1] <= 100);
          Assert.assertTrue("Out of possible value", vals[2] >= 900 && vals[2] <= 1100);
        }
  
        hist.snapshotAndReset();
      }
    }
  
  
    @Test
    public void testGetNumAtOrBelow() {
      long[] VALUES = { 1, 10, 20, 30, 40, 50 };
  
      FastLongHistogram h = new FastLongHistogram();
      for (long v : VALUES) {
       for (int i = 0; i < 100; i++) {
         h.add(v, 1);
       }
     }
 
     h.add(Integer.MAX_VALUE, 1);
 
     h.snapshotAndReset();
 
     for (long v : VALUES) {
       for (int i = 0; i < 100; i++) {
         h.add(v, 1);
       }
     }
     // Add something way out there to make sure it doesn't throw off the counts.
     h.add(Integer.MAX_VALUE, 1);
 
     assertEquals(100, h.getNumAtOrBelow(1));
     assertEquals(200, h.getNumAtOrBelow(11));
     assertEquals(601, h.getNumAtOrBelow(Long.MAX_VALUE));
   }
 
 
   @Test
   public void testSameValues() {
     FastLongHistogram hist = new FastLongHistogram(100);
 
     hist.add(50, 100);
 
     hist.snapshotAndReset();
     doTestUniform(hist);
   }
 }