/*
 * 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.runners.flink.streaming;

import static org.junit.Assert.assertThat;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.nio.ByteBuffer;
import org.apache.beam.runners.core.StateInternals;
import org.apache.beam.runners.core.StateInternalsTest;
import org.apache.beam.runners.core.StateNamespace;
import org.apache.beam.runners.core.StateNamespaceForTest;
import org.apache.beam.runners.core.StateTag;
import org.apache.beam.runners.core.StateTags;
import org.apache.beam.runners.flink.translation.wrappers.streaming.state.FlinkKeyGroupStateInternals;
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.state.BagState;
import org.apache.beam.sdk.util.CoderUtils;
import org.apache.flink.api.common.ExecutionConfig;
import org.apache.flink.api.common.JobID;
import org.apache.flink.api.java.typeutils.GenericTypeInfo;
import org.apache.flink.runtime.jobgraph.JobVertexID;
import org.apache.flink.runtime.operators.testutils.DummyEnvironment;
import org.apache.flink.runtime.query.KvStateRegistry;
import org.apache.flink.runtime.state.AbstractKeyedStateBackend;
import org.apache.flink.runtime.state.KeyGroupRange;
import org.apache.flink.runtime.state.KeyedStateBackend;
import org.apache.flink.runtime.state.memory.MemoryStateBackend;
import org.hamcrest.Matchers;
import org.junit.Ignore;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link FlinkKeyGroupStateInternals}. This is based on the tests for
 * {@code StateInternalsTest}.
 */
public class FlinkKeyGroupStateInternalsTest {

  /**
   * A standard StateInternals test. Just test BagState.
   */
  @RunWith(JUnit4.class)
  public static class StandardStateInternalsTests extends StateInternalsTest {
    @Override
    protected StateInternals createStateInternals() {
      KeyedStateBackend keyedStateBackend =
          getKeyedStateBackend(2, new KeyGroupRange(0, 1));
      return new FlinkKeyGroupStateInternals<>(StringUtf8Coder.of(), keyedStateBackend);
    }

    @Override
    @Ignore
    public void testValue() {}

    @Override
    @Ignore
    public void testSet() {}

    @Override
    @Ignore
    public void testSetIsEmpty() {}

    @Override
    @Ignore
    public void testMergeSetIntoSource() {}

    @Override
    @Ignore
    public void testMergeSetIntoNewNamespace() {}

    @Override
    @Ignore
    public void testMap() {}

    @Override
    @Ignore
    public void testCombiningValue() {}

    @Override
    @Ignore
    public void testCombiningIsEmpty() {}

    @Override
    @Ignore
    public void testMergeCombiningValueIntoSource() {}

    @Override
    @Ignore
    public void testMergeCombiningValueIntoNewNamespace() {}

    @Override
    @Ignore
    public void testWatermarkEarliestState() {}

    @Override
    @Ignore
    public void testWatermarkLatestState() {}

    @Override
    @Ignore
    public void testWatermarkEndOfWindowState() {}

    @Override
    @Ignore
    public void testWatermarkStateIsEmpty() {}

    @Override
    @Ignore
    public void testSetReadable() {}

    @Override
    @Ignore
    public void testMapReadable() {}
  }

  /**
   * A specific test of FlinkKeyGroupStateInternalsTest.
   */
  @RunWith(JUnit4.class)
  public static class OtherTests {

    private static final StateNamespace NAMESPACE_1 = new StateNamespaceForTest("ns1");
    private static final StateNamespace NAMESPACE_2 = new StateNamespaceForTest("ns2");
    private static final StateTag<BagState<String>> STRING_BAG_ADDR =
        StateTags.bag("stringBag", StringUtf8Coder.of());

    @Test
    public void testKeyGroupAndCheckpoint() throws Exception {
      // assign to keyGroup 0
      ByteBuffer key0 = ByteBuffer.wrap(
          CoderUtils.encodeToByteArray(StringUtf8Coder.of(), "11111111"));
      // assign to keyGroup 1
      ByteBuffer key1 = ByteBuffer.wrap(
          CoderUtils.encodeToByteArray(StringUtf8Coder.of(), "22222222"));
      FlinkKeyGroupStateInternals<String> allState;
      {
        KeyedStateBackend<ByteBuffer> keyedStateBackend =
            getKeyedStateBackend(2, new KeyGroupRange(0, 1));
        allState = new FlinkKeyGroupStateInternals<>(
            StringUtf8Coder.of(), keyedStateBackend);
        BagState<String> valueForNamespace0 = allState.state(NAMESPACE_1, STRING_BAG_ADDR);
        BagState<String> valueForNamespace1 = allState.state(NAMESPACE_2, STRING_BAG_ADDR);
        keyedStateBackend.setCurrentKey(key0);
        valueForNamespace0.add("0");
        valueForNamespace1.add("2");
        keyedStateBackend.setCurrentKey(key1);
        valueForNamespace0.add("1");
        valueForNamespace1.add("3");
        assertThat(valueForNamespace0.read(), Matchers.containsInAnyOrder("0", "1"));
        assertThat(valueForNamespace1.read(), Matchers.containsInAnyOrder("2", "3"));
      }

      ClassLoader classLoader = FlinkKeyGroupStateInternalsTest.class.getClassLoader();

      // 1. scale up
      ByteArrayOutputStream out0 = new ByteArrayOutputStream();
      allState.snapshotKeyGroupState(0, new DataOutputStream(out0));
      DataInputStream in0 = new DataInputStream(
          new ByteArrayInputStream(out0.toByteArray()));
      {
        KeyedStateBackend<ByteBuffer> keyedStateBackend =
            getKeyedStateBackend(2, new KeyGroupRange(0, 0));
        FlinkKeyGroupStateInternals<String> state0 =
            new FlinkKeyGroupStateInternals<>(
                StringUtf8Coder.of(), keyedStateBackend);
        state0.restoreKeyGroupState(0, in0, classLoader);
        BagState<String> valueForNamespace0 = state0.state(NAMESPACE_1, STRING_BAG_ADDR);
        BagState<String> valueForNamespace1 = state0.state(NAMESPACE_2, STRING_BAG_ADDR);
        assertThat(valueForNamespace0.read(), Matchers.containsInAnyOrder("0"));
        assertThat(valueForNamespace1.read(), Matchers.containsInAnyOrder("2"));
      }

      ByteArrayOutputStream out1 = new ByteArrayOutputStream();
      allState.snapshotKeyGroupState(1, new DataOutputStream(out1));
      DataInputStream in1 = new DataInputStream(
          new ByteArrayInputStream(out1.toByteArray()));
      {
        KeyedStateBackend<ByteBuffer> keyedStateBackend =
            getKeyedStateBackend(2, new KeyGroupRange(1, 1));
        FlinkKeyGroupStateInternals<String> state1 =
            new FlinkKeyGroupStateInternals<>(
                StringUtf8Coder.of(), keyedStateBackend);
        state1.restoreKeyGroupState(1, in1, classLoader);
        BagState<String> valueForNamespace0 = state1.state(NAMESPACE_1, STRING_BAG_ADDR);
        BagState<String> valueForNamespace1 = state1.state(NAMESPACE_2, STRING_BAG_ADDR);
        assertThat(valueForNamespace0.read(), Matchers.containsInAnyOrder("1"));
        assertThat(valueForNamespace1.read(), Matchers.containsInAnyOrder("3"));
      }

      // 2. scale down
      {
        KeyedStateBackend<ByteBuffer> keyedStateBackend =
            getKeyedStateBackend(2, new KeyGroupRange(0, 1));
        FlinkKeyGroupStateInternals<String> newAllState = new FlinkKeyGroupStateInternals<>(
            StringUtf8Coder.of(), keyedStateBackend);
        in0.reset();
        in1.reset();
        newAllState.restoreKeyGroupState(0, in0, classLoader);
        newAllState.restoreKeyGroupState(1, in1, classLoader);
        BagState<String> valueForNamespace0 = newAllState.state(NAMESPACE_1, STRING_BAG_ADDR);
        BagState<String> valueForNamespace1 = newAllState.state(NAMESPACE_2, STRING_BAG_ADDR);
        assertThat(valueForNamespace0.read(), Matchers.containsInAnyOrder("0", "1"));
        assertThat(valueForNamespace1.read(), Matchers.containsInAnyOrder("2", "3"));
      }
    }

  }

  private static KeyedStateBackend<ByteBuffer> getKeyedStateBackend(int numberOfKeyGroups,
                                                   KeyGroupRange keyGroupRange) {
    MemoryStateBackend backend = new MemoryStateBackend();
    try {
      AbstractKeyedStateBackend<ByteBuffer> keyedStateBackend = backend.createKeyedStateBackend(
          new DummyEnvironment("test", 1, 0),
          new JobID(),
          "test_op",
          new GenericTypeInfo<>(ByteBuffer.class).createSerializer(new ExecutionConfig()),
          numberOfKeyGroups,
          keyGroupRange,
          new KvStateRegistry().createTaskRegistry(new JobID(), new JobVertexID()));
      keyedStateBackend.setCurrentKey(ByteBuffer.wrap(
          CoderUtils.encodeToByteArray(StringUtf8Coder.of(), "1")));
      return keyedStateBackend;
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }

}
