/*
 * 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.arrow.vector;

import static org.apache.arrow.vector.TestUtils.*;
import static org.apache.arrow.vector.testing.ValueVectorDataPopulator.setVector;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.function.ToIntBiFunction;
import org.apache.arrow.memory.ArrowBuf;
import org.apache.arrow.memory.BufferAllocator;
import org.apache.arrow.vector.complex.FixedSizeListVector;
import org.apache.arrow.vector.complex.ListVector;
import org.apache.arrow.vector.complex.StructVector;
import org.apache.arrow.vector.complex.UnionVector;
import org.apache.arrow.vector.complex.impl.NullableStructWriter;
import org.apache.arrow.vector.complex.impl.UnionListWriter;
import org.apache.arrow.vector.dictionary.Dictionary;
import org.apache.arrow.vector.dictionary.DictionaryEncoder;
import org.apache.arrow.vector.dictionary.DictionaryProvider;
import org.apache.arrow.vector.dictionary.ListSubfieldEncoder;
import org.apache.arrow.vector.dictionary.StructSubfieldEncoder;
import org.apache.arrow.vector.holders.NullableIntHolder;
import org.apache.arrow.vector.holders.NullableUInt4Holder;
import org.apache.arrow.vector.types.Types;
import org.apache.arrow.vector.types.pojo.ArrowType;
import org.apache.arrow.vector.types.pojo.DictionaryEncoding;
import org.apache.arrow.vector.types.pojo.FieldType;
import org.apache.arrow.vector.util.Text;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class TestDictionaryVector {

  private BufferAllocator allocator;

  byte[] zero = "foo".getBytes(StandardCharsets.UTF_8);
  byte[] one = "bar".getBytes(StandardCharsets.UTF_8);
  byte[] two = "baz".getBytes(StandardCharsets.UTF_8);

  byte[][] data = new byte[][] {zero, one, two};

  @BeforeEach
  public void init() {
    allocator = new DirtyRootAllocator(Long.MAX_VALUE, (byte) 100);
  }

  @AfterEach
  public void terminate() throws Exception {
    allocator.close();
  }

  @Test
  public void testEncodeStrings() {
    // Create a new value vector
    try (final VarCharVector vector = newVarCharVector("foo", allocator);
        final VarCharVector dictionaryVector = newVarCharVector("dict", allocator); ) {

      setVector(vector, zero, one, one, two, zero);
      setVector(dictionaryVector, zero, one, two);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(5, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(1, index.get(1));
        assertEquals(1, index.get(2));
        assertEquals(2, index.get(3));
        assertEquals(0, index.get(4));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = DictionaryEncoder.decode(encoded, dictionary)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), ((VarCharVector) decoded).getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), ((VarCharVector) decoded).getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeLargeVector() {
    // Create a new value vector
    try (final VarCharVector vector = newVarCharVector("foo", allocator);
        final VarCharVector dictionaryVector = newVarCharVector("dict", allocator); ) {
      vector.allocateNew();

      int count = 10000;

      for (int i = 0; i < 10000; ++i) {
        vector.setSafe(i, data[i % 3], 0, data[i % 3].length);
      }
      vector.setValueCount(count);

      setVector(dictionaryVector, zero, one, two);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(count, index.getValueCount());
        for (int i = 0; i < count; ++i) {
          assertEquals(i % 3, index.get(i));
        }

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = DictionaryEncoder.decode(encoded, dictionary)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < count; ++i) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeList() {
    // Create a new value vector
    try (final ListVector vector = ListVector.empty("vector", allocator);
        final ListVector dictionaryVector = ListVector.empty("dict", allocator); ) {

      UnionListWriter writer = vector.getWriter();
      writer.allocate();

      // set some values
      writeListVector(writer, new int[] {10, 20});
      writeListVector(writer, new int[] {10, 20});
      writeListVector(writer, new int[] {10, 20});
      writeListVector(writer, new int[] {30, 40, 50});
      writeListVector(writer, new int[] {30, 40, 50});
      writeListVector(writer, new int[] {10, 20});

      writer.setValueCount(6);

      UnionListWriter dictWriter = dictionaryVector.getWriter();
      dictWriter.allocate();

      writeListVector(dictWriter, new int[] {10, 20});
      writeListVector(dictWriter, new int[] {30, 40, 50});

      dictWriter.setValueCount(2);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(6, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(0, index.get(1));
        assertEquals(0, index.get(2));
        assertEquals(1, index.get(3));
        assertEquals(1, index.get(4));
        assertEquals(0, index.get(5));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = DictionaryEncoder.decode(encoded, dictionary)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeStruct() {
    // Create a new value vector
    try (final StructVector vector = StructVector.empty("vector", allocator);
        final StructVector dictionaryVector = StructVector.empty("dict", allocator); ) {
      vector.addOrGet("f0", FieldType.nullable(new ArrowType.Int(32, true)), IntVector.class);
      vector.addOrGet("f1", FieldType.nullable(new ArrowType.Int(64, true)), BigIntVector.class);
      dictionaryVector.addOrGet(
          "f0", FieldType.nullable(new ArrowType.Int(32, true)), IntVector.class);
      dictionaryVector.addOrGet(
          "f1", FieldType.nullable(new ArrowType.Int(64, true)), BigIntVector.class);

      NullableStructWriter writer = vector.getWriter();
      writer.allocate();

      writeStructVector(writer, 1, 10L);
      writeStructVector(writer, 1, 10L);
      writeStructVector(writer, 1, 10L);
      writeStructVector(writer, 2, 20L);
      writeStructVector(writer, 2, 20L);
      writeStructVector(writer, 2, 20L);
      writeStructVector(writer, 1, 10L);

      writer.setValueCount(7);

      NullableStructWriter dictWriter = dictionaryVector.getWriter();
      dictWriter.allocate();

      writeStructVector(dictWriter, 1, 10L);
      writeStructVector(dictWriter, 2, 20L);

      dictionaryVector.setValueCount(2);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(7, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(0, index.get(1));
        assertEquals(0, index.get(2));
        assertEquals(1, index.get(3));
        assertEquals(1, index.get(4));
        assertEquals(1, index.get(5));
        assertEquals(0, index.get(6));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = DictionaryEncoder.decode(encoded, dictionary)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeBinaryVector() {
    // Create a new value vector
    try (final VarBinaryVector vector = newVarBinaryVector("foo", allocator);
        final VarBinaryVector dictionaryVector = newVarBinaryVector("dict", allocator)) {

      setVector(vector, zero, one, one, two, zero);
      setVector(dictionaryVector, zero, one, two);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(5, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(1, index.get(1));
        assertEquals(1, index.get(2));
        assertEquals(2, index.get(3));
        assertEquals(0, index.get(4));

        // now run through the decoder and verify we get the original back
        try (VarBinaryVector decoded =
            (VarBinaryVector) DictionaryEncoder.decode(encoded, dictionary)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertTrue(Arrays.equals(vector.getObject(i), decoded.getObject(i)));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeUnion() {
    // Create a new value vector
    try (final UnionVector vector =
            new UnionVector("vector", allocator, /* field type */ null, /* call-back */ null);
        final UnionVector dictionaryVector =
            new UnionVector("dict", allocator, /* field type */ null, /* call-back */ null); ) {

      final NullableUInt4Holder uintHolder1 = new NullableUInt4Holder();
      uintHolder1.value = 10;
      uintHolder1.isSet = 1;

      final NullableIntHolder intHolder1 = new NullableIntHolder();
      intHolder1.value = 10;
      intHolder1.isSet = 1;

      final NullableIntHolder intHolder2 = new NullableIntHolder();
      intHolder2.value = 20;
      intHolder2.isSet = 1;

      // write data
      vector.setType(0, Types.MinorType.UINT4);
      vector.setSafe(0, uintHolder1);

      vector.setType(1, Types.MinorType.INT);
      vector.setSafe(1, intHolder1);

      vector.setType(2, Types.MinorType.INT);
      vector.setSafe(2, intHolder1);

      vector.setType(3, Types.MinorType.INT);
      vector.setSafe(3, intHolder2);

      vector.setType(4, Types.MinorType.INT);
      vector.setSafe(4, intHolder2);

      vector.setValueCount(5);

      // write dictionary
      dictionaryVector.setType(0, Types.MinorType.UINT4);
      dictionaryVector.setSafe(0, uintHolder1);

      dictionaryVector.setType(1, Types.MinorType.INT);
      dictionaryVector.setSafe(1, intHolder1);

      dictionaryVector.setType(2, Types.MinorType.INT);
      dictionaryVector.setSafe(2, intHolder2);

      dictionaryVector.setValueCount(3);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(5, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(1, index.get(1));
        assertEquals(1, index.get(2));
        assertEquals(2, index.get(3));
        assertEquals(2, index.get(4));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = DictionaryEncoder.decode(encoded, dictionary)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testIntEquals() {
    // test Int
    try (final IntVector vector1 = new IntVector("int", allocator);
        final IntVector vector2 = new IntVector("int", allocator)) {

      Dictionary dict1 = new Dictionary(vector1, new DictionaryEncoding(1L, false, null));
      Dictionary dict2 = new Dictionary(vector2, new DictionaryEncoding(1L, false, null));

      setVector(vector1, 1, 2, 3);
      setVector(vector2, 1, 2, 0);

      assertFalse(dict1.equals(dict2));

      vector2.setSafe(2, 3);
      assertTrue(dict1.equals(dict2));
    }
  }

  @Test
  public void testVarcharEquals() {
    try (final VarCharVector vector1 = new VarCharVector("varchar", allocator);
        final VarCharVector vector2 = new VarCharVector("varchar", allocator)) {

      Dictionary dict1 = new Dictionary(vector1, new DictionaryEncoding(1L, false, null));
      Dictionary dict2 = new Dictionary(vector2, new DictionaryEncoding(1L, false, null));

      setVector(vector1, zero, one, two);
      setVector(vector2, zero, one, one);

      assertFalse(dict1.equals(dict2));

      vector2.setSafe(2, two, 0, two.length);
      assertTrue(dict1.equals(dict2));
    }
  }

  @Test
  public void testVarBinaryEquals() {
    try (final VarBinaryVector vector1 = new VarBinaryVector("binary", allocator);
        final VarBinaryVector vector2 = new VarBinaryVector("binary", allocator)) {

      Dictionary dict1 = new Dictionary(vector1, new DictionaryEncoding(1L, false, null));
      Dictionary dict2 = new Dictionary(vector2, new DictionaryEncoding(1L, false, null));

      setVector(vector1, zero, one, two);
      setVector(vector2, zero, one, one);

      assertFalse(dict1.equals(dict2));

      vector2.setSafe(2, two, 0, two.length);
      assertTrue(dict1.equals(dict2));
    }
  }

  @Test
  public void testListEquals() {
    try (final ListVector vector1 = ListVector.empty("list", allocator);
        final ListVector vector2 = ListVector.empty("list", allocator); ) {

      Dictionary dict1 = new Dictionary(vector1, new DictionaryEncoding(1L, false, null));
      Dictionary dict2 = new Dictionary(vector2, new DictionaryEncoding(1L, false, null));

      UnionListWriter writer1 = vector1.getWriter();
      writer1.allocate();

      // set some values
      writeListVector(writer1, new int[] {1, 2});
      writeListVector(writer1, new int[] {3, 4});
      writeListVector(writer1, new int[] {5, 6});
      writer1.setValueCount(3);

      UnionListWriter writer2 = vector2.getWriter();
      writer2.allocate();

      // set some values
      writeListVector(writer2, new int[] {1, 2});
      writeListVector(writer2, new int[] {3, 4});
      writeListVector(writer2, new int[] {5, 6});
      writer2.setValueCount(3);

      assertTrue(dict1.equals(dict2));
    }
  }

  @Test
  public void testStructEquals() {
    try (final StructVector vector1 = StructVector.empty("struct", allocator);
        final StructVector vector2 = StructVector.empty("struct", allocator); ) {
      vector1.addOrGet("f0", FieldType.nullable(new ArrowType.Int(32, true)), IntVector.class);
      vector1.addOrGet("f1", FieldType.nullable(new ArrowType.Int(64, true)), BigIntVector.class);
      vector2.addOrGet("f0", FieldType.nullable(new ArrowType.Int(32, true)), IntVector.class);
      vector2.addOrGet("f1", FieldType.nullable(new ArrowType.Int(64, true)), BigIntVector.class);

      Dictionary dict1 = new Dictionary(vector1, new DictionaryEncoding(1L, false, null));
      Dictionary dict2 = new Dictionary(vector2, new DictionaryEncoding(1L, false, null));

      NullableStructWriter writer1 = vector1.getWriter();
      writer1.allocate();

      writeStructVector(writer1, 1, 10L);
      writeStructVector(writer1, 2, 20L);
      writer1.setValueCount(2);

      NullableStructWriter writer2 = vector2.getWriter();
      writer2.allocate();

      writeStructVector(writer2, 1, 10L);
      writeStructVector(writer2, 2, 20L);
      writer2.setValueCount(2);

      assertTrue(dict1.equals(dict2));
    }
  }

  @Test
  public void testUnionEquals() {
    try (final UnionVector vector1 =
            new UnionVector("union", allocator, /* field type */ null, /* call-back */ null);
        final UnionVector vector2 =
            new UnionVector("union", allocator, /* field type */ null, /* call-back */ null); ) {

      final NullableUInt4Holder uInt4Holder = new NullableUInt4Holder();
      uInt4Holder.value = 10;
      uInt4Holder.isSet = 1;

      final NullableIntHolder intHolder = new NullableIntHolder();
      uInt4Holder.value = 20;
      uInt4Holder.isSet = 1;

      vector1.setType(0, Types.MinorType.UINT4);
      vector1.setSafe(0, uInt4Holder);

      vector1.setType(2, Types.MinorType.INT);
      vector1.setSafe(2, intHolder);
      vector1.setValueCount(3);

      vector2.setType(0, Types.MinorType.UINT4);
      vector2.setSafe(0, uInt4Holder);

      vector2.setType(2, Types.MinorType.INT);
      vector2.setSafe(2, intHolder);
      vector2.setValueCount(3);

      Dictionary dict1 = new Dictionary(vector1, new DictionaryEncoding(1L, false, null));
      Dictionary dict2 = new Dictionary(vector2, new DictionaryEncoding(1L, false, null));

      assertTrue(dict1.equals(dict2));
    }
  }

  @Test
  public void testEncodeWithEncoderInstance() {
    // Create a new value vector
    try (final VarCharVector vector = newVarCharVector("vector", allocator);
        final VarCharVector dictionaryVector = newVarCharVector("dict", allocator); ) {

      setVector(vector, zero, one, one, two, zero);
      setVector(dictionaryVector, zero, one, two);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
      DictionaryEncoder encoder = new DictionaryEncoder(dictionary, allocator);

      try (final ValueVector encoded = encoder.encode(vector)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(5, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(1, index.get(1));
        assertEquals(1, index.get(2));
        assertEquals(2, index.get(3));
        assertEquals(0, index.get(4));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decode(encoded)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), ((VarCharVector) decoded).getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeMultiVectors() {
    // Create a new value vector
    try (final VarCharVector vector1 = newVarCharVector("vector1", allocator);
        final VarCharVector vector2 = newVarCharVector("vector2", allocator);
        final VarCharVector dictionaryVector = newVarCharVector("dict", allocator); ) {

      setVector(vector1, zero, one, one, two, zero);
      setVector(vector2, zero, one, one);
      setVector(dictionaryVector, zero, one, two);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
      DictionaryEncoder encoder = new DictionaryEncoder(dictionary, allocator);

      try (final ValueVector encoded = encoder.encode(vector1)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(5, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(1, index.get(1));
        assertEquals(1, index.get(2));
        assertEquals(2, index.get(3));
        assertEquals(0, index.get(4));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decode(encoded)) {
          assertEquals(vector1.getClass(), decoded.getClass());
          assertEquals(vector1.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector1.getObject(i), ((VarCharVector) decoded).getObject(i));
          }
        }
      }

      try (final ValueVector encoded = encoder.encode(vector2)) {
        // verify indices
        assertEquals(IntVector.class, encoded.getClass());

        IntVector index = ((IntVector) encoded);
        assertEquals(3, index.getValueCount());
        assertEquals(0, index.get(0));
        assertEquals(1, index.get(1));
        assertEquals(1, index.get(2));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decode(encoded)) {
          assertEquals(vector2.getClass(), decoded.getClass());
          assertEquals(vector2.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 3; i++) {
            assertEquals(vector2.getObject(i), ((VarCharVector) decoded).getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeListSubField() {
    // Create a new value vector
    try (final ListVector vector = ListVector.empty("vector", allocator);
        final ListVector dictionaryVector = ListVector.empty("dict", allocator); ) {

      UnionListWriter writer = vector.getWriter();
      writer.allocate();

      // set some values
      writeListVector(writer, new int[] {10, 20});
      writeListVector(writer, new int[] {10, 20});
      writeListVector(writer, new int[] {10, 20});
      writeListVector(writer, new int[] {30, 40, 50});
      writeListVector(writer, new int[] {30, 40, 50});
      writeListVector(writer, new int[] {10, 20});
      writer.setValueCount(6);

      UnionListWriter dictWriter = dictionaryVector.getWriter();
      dictWriter.allocate();
      writeListVector(dictWriter, new int[] {10, 20, 30, 40, 50});
      dictionaryVector.setValueCount(1);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
      ListSubfieldEncoder encoder = new ListSubfieldEncoder(dictionary, allocator);

      try (final ListVector encoded = (ListVector) encoder.encodeListSubField(vector)) {
        // verify indices
        assertEquals(ListVector.class, encoded.getClass());

        assertEquals(6, encoded.getValueCount());
        int[] realValue1 = convertListToIntArray(encoded.getObject(0));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue1));
        int[] realValue2 = convertListToIntArray(encoded.getObject(1));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue2));
        int[] realValue3 = convertListToIntArray(encoded.getObject(2));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue3));
        int[] realValue4 = convertListToIntArray(encoded.getObject(3));
        assertTrue(Arrays.equals(new int[] {2, 3, 4}, realValue4));
        int[] realValue5 = convertListToIntArray(encoded.getObject(4));
        assertTrue(Arrays.equals(new int[] {2, 3, 4}, realValue5));
        int[] realValue6 = convertListToIntArray(encoded.getObject(5));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue6));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decodeListSubField(encoded)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeFixedSizeListSubField() {
    // Create a new value vector
    try (final FixedSizeListVector vector = FixedSizeListVector.empty("vector", 2, allocator);
        final FixedSizeListVector dictionaryVector =
            FixedSizeListVector.empty("dict", 2, allocator)) {

      vector.allocateNew();
      vector.setValueCount(4);

      IntVector dataVector =
          (IntVector)
              vector.addOrGetVector(FieldType.nullable(Types.MinorType.INT.getType())).getVector();
      dataVector.allocateNew(8);
      dataVector.setValueCount(8);
      // set value at index 0
      vector.setNotNull(0);
      dataVector.set(0, 10);
      dataVector.set(1, 20);
      // set value at index 1
      vector.setNotNull(1);
      dataVector.set(2, 10);
      dataVector.set(3, 20);
      // set value at index 2
      vector.setNotNull(2);
      dataVector.set(4, 30);
      dataVector.set(5, 40);
      // set value at index 3
      vector.setNotNull(3);
      dataVector.set(6, 10);
      dataVector.set(7, 20);

      dictionaryVector.allocateNew();
      dictionaryVector.setValueCount(2);
      IntVector dictDataVector =
          (IntVector)
              dictionaryVector
                  .addOrGetVector(FieldType.nullable(Types.MinorType.INT.getType()))
                  .getVector();
      dictDataVector.allocateNew(4);
      dictDataVector.setValueCount(4);

      dictionaryVector.setNotNull(0);
      dictDataVector.set(0, 10);
      dictDataVector.set(1, 20);
      dictionaryVector.setNotNull(1);
      dictDataVector.set(2, 30);
      dictDataVector.set(3, 40);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
      ListSubfieldEncoder encoder = new ListSubfieldEncoder(dictionary, allocator);

      try (final FixedSizeListVector encoded =
          (FixedSizeListVector) encoder.encodeListSubField(vector)) {
        // verify indices
        assertEquals(FixedSizeListVector.class, encoded.getClass());

        assertEquals(4, encoded.getValueCount());
        int[] realValue1 = convertListToIntArray(encoded.getObject(0));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue1));
        int[] realValue2 = convertListToIntArray(encoded.getObject(1));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue2));
        int[] realValue3 = convertListToIntArray(encoded.getObject(2));
        assertTrue(Arrays.equals(new int[] {2, 3}, realValue3));
        int[] realValue4 = convertListToIntArray(encoded.getObject(3));
        assertTrue(Arrays.equals(new int[] {0, 1}, realValue4));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decodeListSubField(encoded)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeStructSubField() {
    try (final StructVector vector = StructVector.empty("vector", allocator);
        final VarCharVector dictVector1 = new VarCharVector("f0", allocator);
        final VarCharVector dictVector2 = new VarCharVector("f1", allocator)) {

      vector.addOrGet("f0", FieldType.nullable(ArrowType.Utf8.INSTANCE), VarCharVector.class);
      vector.addOrGet("f1", FieldType.nullable(ArrowType.Utf8.INSTANCE), VarCharVector.class);

      NullableStructWriter writer = vector.getWriter();
      writer.allocate();
      // set some values
      writeStructVector(writer, "aa", "baz");
      writeStructVector(writer, "bb", "bar");
      writeStructVector(writer, "cc", "foo");
      writeStructVector(writer, "aa", "foo");
      writeStructVector(writer, "dd", "foo");
      writer.setValueCount(5);

      // initialize dictionaries
      DictionaryProvider.MapDictionaryProvider provider =
          new DictionaryProvider.MapDictionaryProvider();

      setVector(
          dictVector1,
          "aa".getBytes(StandardCharsets.UTF_8),
          "bb".getBytes(StandardCharsets.UTF_8),
          "cc".getBytes(StandardCharsets.UTF_8),
          "dd".getBytes(StandardCharsets.UTF_8));
      setVector(
          dictVector2,
          "foo".getBytes(StandardCharsets.UTF_8),
          "baz".getBytes(StandardCharsets.UTF_8),
          "bar".getBytes(StandardCharsets.UTF_8));

      provider.put(new Dictionary(dictVector1, new DictionaryEncoding(1L, false, null)));
      provider.put(new Dictionary(dictVector2, new DictionaryEncoding(2L, false, null)));

      StructSubfieldEncoder encoder = new StructSubfieldEncoder(allocator, provider);
      Map<Integer, Long> columnToDictionaryId = new HashMap<>();
      columnToDictionaryId.put(0, 1L);
      columnToDictionaryId.put(1, 2L);

      try (final StructVector encoded =
          (StructVector) encoder.encode(vector, columnToDictionaryId)) {
        // verify indices
        assertEquals(StructVector.class, encoded.getClass());

        assertEquals(5, encoded.getValueCount());
        Object[] realValue1 = convertMapValuesToArray(encoded.getObject(0));
        assertTrue(Arrays.equals(new Object[] {0, 1}, realValue1));
        Object[] realValue2 = convertMapValuesToArray(encoded.getObject(1));
        assertTrue(Arrays.equals(new Object[] {1, 2}, realValue2));
        Object[] realValue3 = convertMapValuesToArray(encoded.getObject(2));
        assertTrue(Arrays.equals(new Object[] {2, 0}, realValue3));
        Object[] realValue4 = convertMapValuesToArray(encoded.getObject(3));
        assertTrue(Arrays.equals(new Object[] {0, 0}, realValue4));
        Object[] realValue5 = convertMapValuesToArray(encoded.getObject(4));
        assertTrue(Arrays.equals(new Object[] {3, 0}, realValue5));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decode(encoded)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testEncodeStructSubFieldWithCertainColumns() {
    // in this case, some child vector is encoded and others are not
    try (final StructVector vector = StructVector.empty("vector", allocator);
        final VarCharVector dictVector1 = new VarCharVector("f0", allocator)) {

      vector.addOrGet("f0", FieldType.nullable(ArrowType.Utf8.INSTANCE), VarCharVector.class);
      vector.addOrGet("f1", FieldType.nullable(ArrowType.Utf8.INSTANCE), VarCharVector.class);

      NullableStructWriter writer = vector.getWriter();
      writer.allocate();
      // set some values
      writeStructVector(writer, "aa", "baz");
      writeStructVector(writer, "bb", "bar");
      writeStructVector(writer, "cc", "foo");
      writeStructVector(writer, "aa", "foo");
      writeStructVector(writer, "dd", "foo");
      writer.setValueCount(5);

      // initialize dictionaries
      DictionaryProvider.MapDictionaryProvider provider =
          new DictionaryProvider.MapDictionaryProvider();

      setVector(
          dictVector1,
          "aa".getBytes(StandardCharsets.UTF_8),
          "bb".getBytes(StandardCharsets.UTF_8),
          "cc".getBytes(StandardCharsets.UTF_8),
          "dd".getBytes(StandardCharsets.UTF_8));

      provider.put(new Dictionary(dictVector1, new DictionaryEncoding(1L, false, null)));
      StructSubfieldEncoder encoder = new StructSubfieldEncoder(allocator, provider);
      Map<Integer, Long> columnToDictionaryId = new HashMap<>();
      columnToDictionaryId.put(0, 1L);

      try (final StructVector encoded =
          (StructVector) encoder.encode(vector, columnToDictionaryId)) {
        // verify indices
        assertEquals(StructVector.class, encoded.getClass());

        assertEquals(5, encoded.getValueCount());
        Object[] realValue1 = convertMapValuesToArray(encoded.getObject(0));
        assertTrue(Arrays.equals(new Object[] {0, new Text("baz")}, realValue1));
        Object[] realValue2 = convertMapValuesToArray(encoded.getObject(1));
        assertTrue(Arrays.equals(new Object[] {1, new Text("bar")}, realValue2));
        Object[] realValue3 = convertMapValuesToArray(encoded.getObject(2));
        assertTrue(Arrays.equals(new Object[] {2, new Text("foo")}, realValue3));
        Object[] realValue4 = convertMapValuesToArray(encoded.getObject(3));
        assertTrue(Arrays.equals(new Object[] {0, new Text("foo")}, realValue4));
        Object[] realValue5 = convertMapValuesToArray(encoded.getObject(4));
        assertTrue(Arrays.equals(new Object[] {3, new Text("foo")}, realValue5));

        // now run through the decoder and verify we get the original back
        try (ValueVector decoded = encoder.decode(encoded)) {
          assertEquals(vector.getClass(), decoded.getClass());
          assertEquals(vector.getValueCount(), decoded.getValueCount());
          for (int i = 0; i < 5; i++) {
            assertEquals(vector.getObject(i), decoded.getObject(i));
          }
        }
      }
    }
  }

  @Test
  public void testNoMemoryLeak() {
    // test no memory leak when encode
    try (final VarCharVector vector = newVarCharVector("foo", allocator);
        final VarCharVector dictionaryVector = newVarCharVector("dict", allocator)) {

      setVector(vector, zero, one, two);
      setVector(dictionaryVector, zero, one);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector encoded = DictionaryEncoder.encode(vector, dictionary)) {
        fail("There should be an exception when encoding");
      } catch (Exception e) {
        assertEquals("Dictionary encoding not defined for value:" + new Text(two), e.getMessage());
      }
    }
    assertEquals(0, allocator.getAllocatedMemory(), "encode memory leak");

    // test no memory leak when decode
    try (final IntVector indices = newVector(IntVector.class, "", Types.MinorType.INT, allocator);
        final VarCharVector dictionaryVector = newVarCharVector("dict", allocator)) {

      setVector(indices, 3);
      setVector(dictionaryVector, zero, one);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector decoded = DictionaryEncoder.decode(indices, dictionary, allocator)) {
        fail("There should be an exception when decoding");
      } catch (Exception e) {
        assertEquals("Provided dictionary does not contain value for index 3", e.getMessage());
      }
    }
    assertEquals(0, allocator.getAllocatedMemory(), "decode memory leak");
  }

  @Test
  public void testListNoMemoryLeak() {
    // Create a new value vector
    try (final ListVector vector = ListVector.empty("vector", allocator);
        final ListVector dictionaryVector = ListVector.empty("dict", allocator)) {

      UnionListWriter writer = vector.getWriter();
      writer.allocate();
      writeListVector(writer, new int[] {10, 20});
      writer.setValueCount(1);

      UnionListWriter dictWriter = dictionaryVector.getWriter();
      dictWriter.allocate();
      writeListVector(dictWriter, new int[] {10});
      dictionaryVector.setValueCount(1);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));
      ListSubfieldEncoder encoder = new ListSubfieldEncoder(dictionary, allocator);

      try (final ListVector encoded = (ListVector) encoder.encodeListSubField(vector)) {
        fail("There should be an exception when encoding");
      } catch (Exception e) {
        assertEquals("Dictionary encoding not defined for value:20", e.getMessage());
      }
    }
    assertEquals(0, allocator.getAllocatedMemory(), "list encode memory leak");

    try (final ListVector indices = ListVector.empty("indices", allocator);
        final ListVector dictionaryVector = ListVector.empty("dict", allocator)) {

      UnionListWriter writer = indices.getWriter();
      writer.allocate();
      writeListVector(writer, new int[] {3});
      writer.setValueCount(1);

      UnionListWriter dictWriter = dictionaryVector.getWriter();
      dictWriter.allocate();
      writeListVector(dictWriter, new int[] {10, 20});
      dictionaryVector.setValueCount(1);

      Dictionary dictionary =
          new Dictionary(dictionaryVector, new DictionaryEncoding(1L, false, null));

      try (final ValueVector decoded =
          ListSubfieldEncoder.decodeListSubField(indices, dictionary, allocator)) {
        fail("There should be an exception when decoding");
      } catch (Exception e) {
        assertEquals("Provided dictionary does not contain value for index 3", e.getMessage());
      }
    }
    assertEquals(0, allocator.getAllocatedMemory(), "list decode memory leak");
  }

  @Test
  public void testStructNoMemoryLeak() {
    try (final StructVector vector = StructVector.empty("vector", allocator);
        final VarCharVector dictVector1 = new VarCharVector("f0", allocator);
        final VarCharVector dictVector2 = new VarCharVector("f1", allocator)) {

      vector.addOrGet("f0", FieldType.nullable(ArrowType.Utf8.INSTANCE), VarCharVector.class);
      vector.addOrGet("f1", FieldType.nullable(ArrowType.Utf8.INSTANCE), VarCharVector.class);

      NullableStructWriter writer = vector.getWriter();
      writer.allocate();
      writeStructVector(writer, "aa", "baz");
      writer.setValueCount(1);

      DictionaryProvider.MapDictionaryProvider provider =
          new DictionaryProvider.MapDictionaryProvider();
      setVector(dictVector1, "aa".getBytes(StandardCharsets.UTF_8));
      setVector(dictVector2, "foo".getBytes(StandardCharsets.UTF_8));

      provider.put(new Dictionary(dictVector1, new DictionaryEncoding(1L, false, null)));
      provider.put(new Dictionary(dictVector2, new DictionaryEncoding(2L, false, null)));

      StructSubfieldEncoder encoder = new StructSubfieldEncoder(allocator, provider);
      Map<Integer, Long> columnToDictionaryId = new HashMap<>();
      columnToDictionaryId.put(0, 1L);
      columnToDictionaryId.put(1, 2L);

      try (final StructVector encoded =
          (StructVector) encoder.encode(vector, columnToDictionaryId)) {
        fail("There should be an exception when encoding");
      } catch (Exception e) {
        assertEquals("Dictionary encoding not defined for value:baz", e.getMessage());
      }
    }
    assertEquals(0, allocator.getAllocatedMemory(), "struct encode memory leak");

    try (final StructVector indices = StructVector.empty("indices", allocator);
        final VarCharVector dictVector1 = new VarCharVector("f0", allocator);
        final VarCharVector dictVector2 = new VarCharVector("f1", allocator)) {

      DictionaryProvider.MapDictionaryProvider provider =
          new DictionaryProvider.MapDictionaryProvider();
      setVector(dictVector1, "aa".getBytes(StandardCharsets.UTF_8));
      setVector(dictVector2, "foo".getBytes(StandardCharsets.UTF_8));

      provider.put(new Dictionary(dictVector1, new DictionaryEncoding(1L, false, null)));
      provider.put(new Dictionary(dictVector2, new DictionaryEncoding(2L, false, null)));

      ArrowType int32 = new ArrowType.Int(32, true);
      indices.addOrGet(
          "f0", new FieldType(true, int32, provider.lookup(1L).getEncoding()), IntVector.class);
      indices.addOrGet(
          "f1", new FieldType(true, int32, provider.lookup(2L).getEncoding()), IntVector.class);

      NullableStructWriter writer = indices.getWriter();
      writer.allocate();
      writer.start();
      writer.integer("f0").writeInt(1);
      writer.integer("f1").writeInt(3);
      writer.end();
      writer.setValueCount(1);

      try (final StructVector decode = StructSubfieldEncoder.decode(indices, provider, allocator)) {
        fail("There should be an exception when decoding");
      } catch (Exception e) {
        assertEquals("Provided dictionary does not contain value for index 3", e.getMessage());
      }
    }
    assertEquals(0, allocator.getAllocatedMemory(), "struct decode memory leak");
  }

  private void testDictionary(
      Dictionary dictionary, ToIntBiFunction<ValueVector, Integer> valGetter) {
    try (VarCharVector vector = new VarCharVector("vector", allocator)) {
      setVector(vector, "1", "3", "5", "7", "9");
      try (ValueVector encodedVector = DictionaryEncoder.encode(vector, dictionary)) {

        // verify encoded result
        assertEquals(vector.getValueCount(), encodedVector.getValueCount());
        assertEquals(1, valGetter.applyAsInt(encodedVector, 0));
        assertEquals(3, valGetter.applyAsInt(encodedVector, 1));
        assertEquals(5, valGetter.applyAsInt(encodedVector, 2));
        assertEquals(7, valGetter.applyAsInt(encodedVector, 3));
        assertEquals(9, valGetter.applyAsInt(encodedVector, 4));

        try (ValueVector decodedVector = DictionaryEncoder.decode(encodedVector, dictionary)) {
          assertTrue(decodedVector instanceof VarCharVector);
          assertEquals(vector.getValueCount(), decodedVector.getValueCount());
          assertArrayEquals(
              "1".getBytes(StandardCharsets.UTF_8), ((VarCharVector) decodedVector).get(0));
          assertArrayEquals(
              "3".getBytes(StandardCharsets.UTF_8), ((VarCharVector) decodedVector).get(1));
          assertArrayEquals(
              "5".getBytes(StandardCharsets.UTF_8), ((VarCharVector) decodedVector).get(2));
          assertArrayEquals(
              "7".getBytes(StandardCharsets.UTF_8), ((VarCharVector) decodedVector).get(3));
          assertArrayEquals(
              "9".getBytes(StandardCharsets.UTF_8), ((VarCharVector) decodedVector).get(4));
        }
      }
    }
  }

  @Test
  public void testDictionaryUInt1() {
    try (VarCharVector dictionaryVector = new VarCharVector("dict vector", allocator)) {
      setVector(dictionaryVector, "0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
      Dictionary dictionary1 =
          new Dictionary(
              dictionaryVector,
              new DictionaryEncoding(
                  /*id=*/ 10L,
                  /*ordered=*/ false,
                  /*indexType=*/ new ArrowType.Int(/*bitWidth*/ 8, /*isSigned*/ false)));
      testDictionary(dictionary1, (vector, index) -> ((UInt1Vector) vector).get(index));
    }
  }

  @Test
  public void testDictionaryUInt2() {
    try (VarCharVector dictionaryVector = new VarCharVector("dict vector", allocator)) {
      setVector(dictionaryVector, "0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
      Dictionary dictionary2 =
          new Dictionary(
              dictionaryVector,
              new DictionaryEncoding(
                  /*id=*/ 20L,
                  /*ordered=*/ false,
                  /*indexType=*/ new ArrowType.Int(/*bitWidth=*/ 16, /*isSigned*/ false)));
      testDictionary(dictionary2, (vector, index) -> ((UInt2Vector) vector).get(index));
    }
  }

  @Test
  public void testDictionaryUInt4() {
    try (VarCharVector dictionaryVector = new VarCharVector("dict vector", allocator)) {
      setVector(dictionaryVector, "0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
      Dictionary dictionary4 =
          new Dictionary(
              dictionaryVector,
              new DictionaryEncoding(
                  /*id=*/ 30L,
                  /*ordered=*/ false,
                  /*indexType=*/ new ArrowType.Int(/*bitWidth=*/ 32, /*isSigned*/ false)));
      testDictionary(dictionary4, (vector, index) -> ((UInt4Vector) vector).get(index));
    }
  }

  @Test
  public void testDictionaryUInt8() {
    try (VarCharVector dictionaryVector = new VarCharVector("dict vector", allocator)) {
      setVector(dictionaryVector, "0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
      Dictionary dictionary8 =
          new Dictionary(
              dictionaryVector,
              new DictionaryEncoding(
                  /*id=*/ 40L,
                  /*ordered=*/ false,
                  /*indexType=*/ new ArrowType.Int(/*bitWidth=*/ 64, /*isSigned*/ false)));
      testDictionary(dictionary8, (vector, index) -> (int) ((UInt8Vector) vector).get(index));
    }
  }

  @Test
  public void testDictionaryUIntOverflow() {
    // the size is within the range of UInt1, but outside the range of TinyInt.
    final int vecLength = 256;
    try (VarCharVector dictionaryVector = new VarCharVector("dict vector", allocator)) {
      dictionaryVector.allocateNew(vecLength * 3, vecLength);
      for (int i = 0; i < vecLength; i++) {
        dictionaryVector.set(i, String.valueOf(i).getBytes(StandardCharsets.UTF_8));
      }
      dictionaryVector.setValueCount(vecLength);

      Dictionary dictionary =
          new Dictionary(
              dictionaryVector,
              new DictionaryEncoding(
                  /*id=*/ 10L,
                  /*ordered=*/ false,
                  /*indexType=*/ new ArrowType.Int(/*bitWidth=*/ 8, /*isSigned*/ false)));

      try (VarCharVector vector = new VarCharVector("vector", allocator)) {
        setVector(vector, "255");
        try (UInt1Vector encodedVector =
            (UInt1Vector) DictionaryEncoder.encode(vector, dictionary)) {

          // verify encoded result
          assertEquals(1, encodedVector.getValueCount());
          assertEquals(255, encodedVector.getValueAsLong(0));

          try (VarCharVector decodedVector =
              (VarCharVector) DictionaryEncoder.decode(encodedVector, dictionary)) {
            assertEquals(1, decodedVector.getValueCount());
            assertArrayEquals("255".getBytes(StandardCharsets.UTF_8), decodedVector.get(0));
          }
        }
      }
    }
  }

  private int[] convertListToIntArray(List list) {
    int[] values = new int[list.size()];
    for (int i = 0; i < list.size(); i++) {
      values[i] = (int) list.get(i);
    }
    return values;
  }

  private Object[] convertMapValuesToArray(Map map) {
    Object[] values = new Object[map.size()];
    Iterator valueIterator = map.values().iterator();
    for (int i = 0; i < map.size(); i++) {
      values[i] = valueIterator.next();
    }
    return values;
  }

  private void writeStructVector(NullableStructWriter writer, String value1, String value2) {

    byte[] bytes1 = value1.getBytes(StandardCharsets.UTF_8);
    byte[] bytes2 = value2.getBytes(StandardCharsets.UTF_8);
    ArrowBuf temp = allocator.buffer(bytes1.length > bytes2.length ? bytes1.length : bytes2.length);

    writer.start();
    temp.setBytes(0, bytes1);
    writer.varChar("f0").writeVarChar(0, bytes1.length, temp);
    temp.setBytes(0, bytes2);
    writer.varChar("f1").writeVarChar(0, bytes2.length, temp);
    writer.end();
    temp.close();
  }

  private void writeStructVector(NullableStructWriter writer, int value1, long value2) {
    writer.start();
    writer.integer("f0").writeInt(value1);
    writer.bigInt("f1").writeBigInt(value2);
    writer.end();
  }

  private void writeListVector(UnionListWriter writer, int[] values) {
    writer.startList();
    for (int v : values) {
      writer.integer().writeInt(v);
    }
    writer.endList();
  }
}
