/*
 * 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.transforms.join;

import static org.hamcrest.Matchers.contains;
import static org.hamcrest.Matchers.emptyIterable;
import static org.hamcrest.Matchers.equalTo;
import static org.junit.Assert.assertThat;

import java.util.ArrayList;
import java.util.List;
import org.apache.beam.sdk.util.common.Reiterable;
import org.apache.beam.sdk.util.common.Reiterator;
import org.apache.beam.sdk.values.TupleTag;
import org.apache.beam.sdk.values.TupleTagList;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests the CoGbkResult.
 */
@RunWith(JUnit4.class)
public class CoGbkResultTest {

  @Test
  public void testLazyResults() {
    runLazyResult(0);
    runLazyResult(1);
    runLazyResult(3);
    runLazyResult(10);
  }

  public void runLazyResult(int cacheSize) {
    int valueLen = 7;
    TestUnionValues values = new TestUnionValues(0, 1, 0, 3, 0, 3, 3);
    CoGbkResult result = new CoGbkResult(createSchema(5), values, cacheSize);
    assertThat(values.maxPos(), equalTo(Math.min(cacheSize, valueLen)));
    assertThat(result.getAll(new TupleTag<Integer>("tag0")), contains(0, 2, 4));
    assertThat(values.maxPos(), equalTo(valueLen));
    assertThat(result.getAll(new TupleTag<Integer>("tag3")), contains(3, 5, 6));
    assertThat(result.getAll(new TupleTag<Integer>("tag2")), emptyIterable());
    assertThat(result.getOnly(new TupleTag<Integer>("tag1")), equalTo(1));
    assertThat(result.getAll(new TupleTag<Integer>("tag0")), contains(0, 2, 4));
  }

  private CoGbkResultSchema createSchema(int size) {
    List<TupleTag<?>> tags = new ArrayList<>();
    for (int i = 0; i < size; i++) {
      tags.add(new TupleTag<Integer>("tag" + i));
    }
    return new CoGbkResultSchema(TupleTagList.of(tags));
  }

  private static class TestUnionValues implements Reiterable<RawUnionValue> {

    final int[] tags;
    int maxPos = 0;

    /**
     * This will create a list of RawUnionValues whose tags are as given and
     * values are increasing starting at 0 (i.e. the index in the constructor).
     */
    public TestUnionValues(int... tags) {
      this.tags = tags;
    }

    /**
     * Returns the highest position iterated to so far, useful for ensuring
     * laziness.
     */
    public int maxPos() {
      return maxPos;
    }

    @Override
    public Reiterator<RawUnionValue> iterator() {
      return iterator(0);
    }

    public Reiterator<RawUnionValue> iterator(final int start) {
      return new Reiterator<RawUnionValue>() {
        int pos = start;

        @Override
        public boolean hasNext() {
          return pos < tags.length;
        }

        @Override
        public RawUnionValue next() {
          maxPos = Math.max(pos + 1, maxPos);
          return new RawUnionValue(tags[pos], pos++);
        }

        @Override
        public void remove() {
          throw new UnsupportedOperationException();
        }

        @Override
        public Reiterator<RawUnionValue> copy() {
          return iterator(pos);
        }
      };
    }
  }
}