/*
 * 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.beam.sdk.coders;

import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import com.google.common.collect.ImmutableList;
import java.util.Arrays;
import java.util.List;
import org.apache.beam.sdk.testing.CoderProperties;
import org.apache.beam.sdk.transforms.windowing.GlobalWindow;
import org.apache.beam.sdk.util.CoderUtils;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for {@link LengthPrefixCoder}. */
@RunWith(JUnit4.class)
public class LengthPrefixCoderTest {
  private static final StructuredCoder<byte[]> TEST_CODER =
      LengthPrefixCoder.of(ByteArrayCoder.of());

  private static final List<byte[]> TEST_VALUES = Arrays.asList(
    new byte[]{ 0xa, 0xb, 0xc },
    new byte[]{ 0xd, 0x3 },
    new byte[]{ 0xd, 0xe },
    new byte[]{ });

  /**
   * Generated data to check that the wire format has not changed. To regenerate, see
   * {@link org.apache.beam.sdk.coders.PrintBase64Encodings}.
   */
  private static final ImmutableList<String> TEST_ENCODINGS = ImmutableList.of(
      "AwoLDA",
      "Ag0D",
      "Ag0O",
      "AA");

  @Test
  public void testCoderSerializable() throws Exception {
    CoderProperties.coderSerializable(TEST_CODER);
  }

  @Test
  public void testCoderIsSerializableWithWellKnownCoderType() throws Exception {
    CoderProperties.coderSerializable(LengthPrefixCoder.of(GlobalWindow.Coder.INSTANCE));
  }

  @Test
  public void testEncodedSize() throws Exception {
    assertEquals(5L,
        TEST_CODER.getEncodedElementByteSize(TEST_VALUES.get(0)));
  }

  @Test
  public void testObserverIsCheap() throws Exception {
    LengthPrefixCoder<Double> coder = LengthPrefixCoder.of(DoubleCoder.of());
    assertTrue(coder.isRegisterByteSizeObserverCheap(5.0));
  }

  @Test
  public void testObserverIsNotCheap() throws Exception {
    LengthPrefixCoder<List<String>> coder =
        LengthPrefixCoder.of(ListCoder.of(StringUtf8Coder.of()));
    assertFalse(coder.isRegisterByteSizeObserverCheap(
        ImmutableList.of("hi", "test")));
  }

  @Test
  public void testDecodeEncodeEquals() throws Exception {
    for (byte[] value : TEST_VALUES) {
      CoderProperties.coderDecodeEncodeEqual(TEST_CODER, value);
    }
  }

  @Test
  public void testRegisterByteSizeObserver() throws Exception {
    CoderProperties.testByteCount(
        LengthPrefixCoder.of(VarIntCoder.of()),
        Coder.Context.NESTED,
        new Integer[]{0, 10, 1000});
  }

  @Test
  public void testStructuralValueConsistentWithEquals() throws Exception {
    for (byte[] value1 : TEST_VALUES) {
      for (byte[] value2 : TEST_VALUES) {
        CoderProperties.structuralValueConsistentWithEquals(TEST_CODER, value1, value2);
      }
    }
  }

  @Test
  public void testWireFormatEncode() throws Exception {
    CoderProperties.coderEncodesBase64(TEST_CODER, TEST_VALUES, TEST_ENCODINGS);
  }

  @Test
  public void testMultiCoderCycle() throws Exception {
    LengthPrefixCoder<Long> lengthPrefixedValueCoder =
        LengthPrefixCoder.of(BigEndianLongCoder.of());

    LengthPrefixCoder<byte[]> lengthPrefixedBytesCoder = LengthPrefixCoder.of(ByteArrayCoder.of());

    // [0x08, 0, 0, 0, 0, 0, 0, 0, 0x16]
    byte[] userEncoded = CoderUtils.encodeToByteArray(lengthPrefixedValueCoder, 22L);

    // [0, 0, 0, 0, 0, 0, 0, 0x16]
    byte[] decodedToBytes = CoderUtils.decodeFromByteArray(lengthPrefixedBytesCoder, userEncoded);

    // [0x08, 0, 0, 0, 0, 0, 0, 0, 0x16]
    byte[] reencodedBytes = CoderUtils.encodeToByteArray(lengthPrefixedBytesCoder, decodedToBytes);

    long userDecoded = CoderUtils.decodeFromByteArray(lengthPrefixedValueCoder, reencodedBytes);

    assertFalse(
        "Length-prefix decoding to bytes should drop the length",
        Arrays.equals(userEncoded, decodedToBytes));
    assertArrayEquals(userEncoded, reencodedBytes);
    assertEquals(22L, userDecoded);
  }
}
