/*
 * 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.util;

import com.google.common.collect.FluentIterable;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import org.apache.beam.sdk.coders.ByteArrayCoder;
import org.apache.beam.sdk.coders.IterableCoder;
import org.apache.beam.sdk.coders.ListCoder;
import org.apache.beam.sdk.coders.VarIntCoder;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link MutationDetectors}.
 */
@RunWith(JUnit4.class)
public class MutationDetectorsTest {

  @Rule public ExpectedException thrown = ExpectedException.none();

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} detects a mutation to a list.
   */
  @Test
  public void testMutatingList() throws Exception {
    List<Integer> value = Arrays.asList(1, 2, 3, 4);
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, ListCoder.of(VarIntCoder.of()));
    value.set(0, 37);

    thrown.expect(IllegalMutationException.class);
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} does not false positive on a
   * {@link LinkedList} that will clone as an {@code ArrayList}.
   */
  @Test
  public void testUnmodifiedLinkedList() throws Exception {
    List<Integer> value = Lists.newLinkedList(Arrays.asList(1, 2, 3, 4));
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, ListCoder.of(VarIntCoder.of()));
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} does not false positive on a
   * {@link LinkedList} coded as an {@link Iterable}.
   */
  @Test
  public void testImmutableList() throws Exception {
    List<Integer> value = Lists.newLinkedList(Arrays.asList(1, 2, 3, 4));
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, IterableCoder.of(VarIntCoder.of()));
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} does not false positive on a
   * {@link Set} coded as an {@link Iterable}.
   */
  @Test
  public void testImmutableSet() throws Exception {
    Set<Integer> value = Sets.newHashSet(Arrays.asList(1, 2, 3, 4));
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, IterableCoder.of(VarIntCoder.of()));
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} does not false positive on an
   * {@link Iterable} that is not known to be bounded; after coder-based cloning the bound
   * will be known and it will be a {@link List} so it will encode more compactly the second
   * time around.
   */
  @Test
  public void testImmutableIterable() throws Exception {
    Iterable<Integer> value = FluentIterable.from(Arrays.asList(1, 2, 3, 4)).cycle().limit(50);
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, IterableCoder.of(VarIntCoder.of()));
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} detects a mutation to a byte array.
   */
  @Test
  public void testMutatingArray() throws Exception {
    byte[] value = new byte[]{0x1, 0x2, 0x3, 0x4};
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, ByteArrayCoder.of());
    value[0] = 0xa;
    thrown.expect(IllegalMutationException.class);
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} does not false positive on an
   * array, even though it will decode is another array which Java will not say is {@code equals}.
   */
  @Test
  public void testUnmodifiedArray() throws Exception {
    byte[] value = new byte[]{0x1, 0x2, 0x3, 0x4};
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, ByteArrayCoder.of());
    detector.verifyUnmodified();
  }

  /**
   * Tests that {@link MutationDetectors#forValueWithCoder} does not false positive on an
   * list of arrays, even when some array is set to a deeply equal array that is not {@code equals}.
   */
  @Test
  public void testEquivalentListOfArrays() throws Exception {
    List<byte[]> value = Arrays.asList(new byte[]{0x1}, new byte[]{0x2, 0x3}, new byte[]{0x4});
    MutationDetector detector =
        MutationDetectors.forValueWithCoder(value, ListCoder.of(ByteArrayCoder.of()));
    value.set(0, new byte[]{0x1});
    detector.verifyUnmodified();
  }
}