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 * 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.util;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.Random;
import java.util.TreeMap;
import java.util.concurrent.ThreadLocalRandom;
import org.apache.hadoop.hbase.testclassification.MediumTests;
import org.apache.hadoop.hbase.testclassification.MiscTests;
import org.apache.hadoop.hbase.util.AvlUtil.AvlIterableList;
import org.apache.hadoop.hbase.util.AvlUtil.AvlKeyComparator;
import org.apache.hadoop.hbase.util.AvlUtil.AvlLinkedNode;
import org.apache.hadoop.hbase.util.AvlUtil.AvlNode;
import org.apache.hadoop.hbase.util.AvlUtil.AvlNodeVisitor;
import org.apache.hadoop.hbase.util.AvlUtil.AvlTree;
import org.apache.hadoop.hbase.util.AvlUtil.AvlTreeIterator;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

@Tag(MiscTests.TAG)
@Tag(MediumTests.TAG)
public class TestAvlUtil {

  private static final TestAvlKeyComparator KEY_COMPARATOR = new TestAvlKeyComparator();

  @Test
  public void testAvlTreeCrud() {
    final int MAX_KEY = 99999999;
    final int NELEM = 10000;

    final TreeMap<Integer, Object> treeMap = new TreeMap<>();
    TestAvlNode root = null;

    Random rand = ThreadLocalRandom.current();
    for (int i = 0; i < NELEM; ++i) {
      int key = rand.nextInt(MAX_KEY);
      if (AvlTree.get(root, key, KEY_COMPARATOR) != null) {
        i--;
        continue;
      }
      root = AvlTree.insert(root, new TestAvlNode(key));
      treeMap.put(key, null);
      for (Integer keyX : treeMap.keySet()) {
        TestAvlNode node = AvlTree.get(root, keyX, KEY_COMPARATOR);
        assertNotNull(node);
        assertEquals(keyX.intValue(), node.getKey());
      }
    }

    for (int i = 0; i < NELEM; ++i) {
      int key = rand.nextInt(MAX_KEY);
      TestAvlNode node = AvlTree.get(root, key, KEY_COMPARATOR);
      if (!treeMap.containsKey(key)) {
        assertNull(node);
        continue;
      }
      treeMap.remove(key);
      assertEquals(key, node.getKey());
      root = AvlTree.remove(root, key, KEY_COMPARATOR);
      for (Integer keyX : treeMap.keySet()) {
        node = AvlTree.get(root, keyX, KEY_COMPARATOR);
        assertNotNull(node);
        assertEquals(keyX.intValue(), node.getKey());
      }
    }
  }

  @Test
  public void testAvlTreeVisitor() {
    final int MIN_KEY = 0;
    final int MAX_KEY = 50;

    TestAvlNode root = null;
    for (int i = MAX_KEY; i >= MIN_KEY; --i) {
      root = AvlTree.insert(root, new TestAvlNode(i));
    }

    AvlTree.visit(root, new AvlNodeVisitor<TestAvlNode>() {
      private int prevKey = -1;

      @Override
      public boolean visitNode(TestAvlNode node) {
        assertEquals(prevKey, node.getKey() - 1);
        assertTrue(node.getKey() >= MIN_KEY);
        assertTrue(node.getKey() <= MAX_KEY);
        prevKey = node.getKey();
        return node.getKey() <= MAX_KEY;
      }
    });
  }

  @Test
  public void testAvlTreeIterSeekFirst() {
    final int MIN_KEY = 1;
    final int MAX_KEY = 50;

    TestAvlNode root = null;
    for (int i = MIN_KEY; i < MAX_KEY; ++i) {
      root = AvlTree.insert(root, new TestAvlNode(i));
    }

    AvlTreeIterator<TestAvlNode> iter = new AvlTreeIterator<>(root);
    assertTrue(iter.hasNext());
    long prevKey = 0;
    while (iter.hasNext()) {
      TestAvlNode node = iter.next();
      assertEquals(prevKey + 1, node.getKey());
      prevKey = node.getKey();
    }
    assertEquals(MAX_KEY - 1, prevKey);
  }

  @Test
  public void testAvlTreeIterSeekTo() {
    final int MIN_KEY = 1;
    final int MAX_KEY = 50;

    TestAvlNode root = null;
    for (int i = MIN_KEY; i < MAX_KEY; i += 2) {
      root = AvlTree.insert(root, new TestAvlNode(i));
    }

    for (int i = MIN_KEY - 1; i < MAX_KEY + 1; ++i) {
      AvlTreeIterator<TestAvlNode> iter = new AvlTreeIterator<>(root, i, KEY_COMPARATOR);
      if (i < MAX_KEY) {
        assertTrue(iter.hasNext());
      } else {
        // searching for something greater than the last node
        assertFalse(iter.hasNext());
        break;
      }

      TestAvlNode node = iter.next();
      assertEquals((i % 2 == 0) ? i + 1 : i, node.getKey());

      long prevKey = node.getKey();
      while (iter.hasNext()) {
        node = iter.next();
        assertTrue(node.getKey() > prevKey);
        prevKey = node.getKey();
      }
    }
  }

  @Test
  public void testAvlIterableListCrud() {
    final int NITEMS = 10;
    TestLinkedAvlNode prependHead = null;
    TestLinkedAvlNode appendHead = null;
    // prepend()/append()
    for (int i = 0; i <= NITEMS; ++i) {
      TestLinkedAvlNode pNode = new TestLinkedAvlNode(i);
      assertFalse(AvlIterableList.isLinked(pNode));
      prependHead = AvlIterableList.prepend(prependHead, pNode);
      assertTrue(AvlIterableList.isLinked(pNode));

      TestLinkedAvlNode aNode = new TestLinkedAvlNode(i);
      assertFalse(AvlIterableList.isLinked(aNode));
      appendHead = AvlIterableList.append(appendHead, aNode);
      assertTrue(AvlIterableList.isLinked(aNode));
    }
    // readNext()
    TestLinkedAvlNode pNode = prependHead;
    TestLinkedAvlNode aNode = appendHead;
    for (int i = 0; i <= NITEMS; ++i) {
      assertEquals(NITEMS - i, pNode.getKey());
      pNode = AvlIterableList.readNext(pNode);

      assertEquals(i, aNode.getKey());
      aNode = AvlIterableList.readNext(aNode);
    }
    // readPrev()
    pNode = AvlIterableList.readPrev(prependHead);
    aNode = AvlIterableList.readPrev(appendHead);
    for (int i = 0; i <= NITEMS; ++i) {
      assertEquals(i, pNode.getKey());
      pNode = AvlIterableList.readPrev(pNode);

      assertEquals(NITEMS - i, aNode.getKey());
      aNode = AvlIterableList.readPrev(aNode);
    }
    // appendList()
    TestLinkedAvlNode node = AvlIterableList.appendList(prependHead, appendHead);
    for (int i = NITEMS; i >= 0; --i) {
      assertEquals(i, node.getKey());
      node = AvlIterableList.readNext(node);
    }
    for (int i = 0; i <= NITEMS; ++i) {
      assertEquals(i, node.getKey());
      node = AvlIterableList.readNext(node);
    }
  }

  private static class TestAvlNode extends AvlNode<TestAvlNode> {
    private final int key;

    public TestAvlNode(int key) {
      this.key = key;
    }

    public int getKey() {
      return key;
    }

    @Override
    public int compareTo(TestAvlNode other) {
      return this.key - other.key;
    }

    @Override
    public String toString() {
      return String.format("TestAvlNode(%d)", key);
    }
  }

  private static class TestLinkedAvlNode extends AvlLinkedNode<TestLinkedAvlNode> {
    private final int key;

    public TestLinkedAvlNode(int key) {
      this.key = key;
    }

    public int getKey() {
      return key;
    }

    @Override
    public int compareTo(TestLinkedAvlNode other) {
      return this.key - other.key;
    }

    @Override
    public String toString() {
      return String.format("TestLinkedAvlNode(%d)", key);
    }
  }

  private static class TestAvlKeyComparator implements AvlKeyComparator<TestAvlNode> {
    @Override
    public int compareKey(TestAvlNode node, Object key) {
      return node.getKey() - (int) key;
    }
  }
}