content: /*
   * Copyright (C) 2017 The Android Open Source Project
   *
   * Licensed 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 com.google.android.exoplayer2.source;
  
  import static com.google.common.truth.Truth.assertThat;
  
  import androidx.test.ext.junit.runners.AndroidJUnit4;
  import com.google.android.exoplayer2.C;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  
  /** Unit test for {@link CompositeSequenceableLoader}. */
  @RunWith(AndroidJUnit4.class)
  public final class CompositeSequenceableLoaderTest {
  
    /**
     * Tests that {@link CompositeSequenceableLoader#getBufferedPositionUs()} returns minimum buffered
     * position among all sub-loaders.
     */
    @Test
    public void getBufferedPositionUsReturnsMinimumLoaderBufferedPosition() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
      assertThat(compositeSequenceableLoader.getBufferedPositionUs()).isEqualTo(1000);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#getBufferedPositionUs()} returns minimum buffered
     * position that is not {@link C#TIME_END_OF_SOURCE} among all sub-loaders.
     */
    @Test
    public void getBufferedPositionUsReturnsMinimumNonEndOfSourceLoaderBufferedPosition() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader3 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ C.TIME_END_OF_SOURCE,
              /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2, loader3});
      assertThat(compositeSequenceableLoader.getBufferedPositionUs()).isEqualTo(1000);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#getBufferedPositionUs()} returns {@link
     * C#TIME_END_OF_SOURCE} when all sub-loaders have buffered till end-of-source.
     */
    @Test
    public void getBufferedPositionUsReturnsEndOfSourceWhenAllLoaderBufferedTillEndOfSource() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ C.TIME_END_OF_SOURCE,
              /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ C.TIME_END_OF_SOURCE,
              /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
      assertThat(compositeSequenceableLoader.getBufferedPositionUs()).isEqualTo(C.TIME_END_OF_SOURCE);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#getNextLoadPositionUs()} returns minimum next
     * load position among all sub-loaders.
     */
    @Test
    public void getNextLoadPositionUsReturnMinimumLoaderNextLoadPositionUs() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2001);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2000);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
      assertThat(compositeSequenceableLoader.getNextLoadPositionUs()).isEqualTo(2000);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#getNextLoadPositionUs()} returns minimum next
     * load position that is not {@link C#TIME_END_OF_SOURCE} among all sub-loaders.
     */
    @Test
    public void getNextLoadPositionUsReturnMinimumNonEndOfSourceLoaderNextLoadPositionUs() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
      FakeSequenceableLoader loader3 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2, loader3});
      assertThat(compositeSequenceableLoader.getNextLoadPositionUs()).isEqualTo(2000);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#getNextLoadPositionUs()} returns {@link
     * C#TIME_END_OF_SOURCE} when all sub-loaders have next load position at end-of-source.
     */
    @Test
    public void getNextLoadPositionUsReturnsEndOfSourceWhenAllLoaderLoadingLastChunk() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
      assertThat(compositeSequenceableLoader.getNextLoadPositionUs()).isEqualTo(C.TIME_END_OF_SOURCE);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} only allows the loader
     * with minimum next load position to continue loading if next load positions are not behind
     * current playback position.
     */
    @Test
    public void continueLoadingOnlyAllowFurthestBehindLoaderToLoadIfNotBehindPlaybackPosition() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
      compositeSequenceableLoader.continueLoading(100);
  
      assertThat(loader1.numInvocations).isEqualTo(1);
      assertThat(loader2.numInvocations).isEqualTo(0);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} allows all loaders with
     * next load position behind current playback position to continue loading.
     */
    @Test
    public void continueLoadingReturnAllowAllLoadersBehindPlaybackPositionToLoad() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
      FakeSequenceableLoader loader3 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1002, /* nextLoadPositionUs */ 2002);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2, loader3});
      compositeSequenceableLoader.continueLoading(3000);
  
      assertThat(loader1.numInvocations).isEqualTo(1);
      assertThat(loader2.numInvocations).isEqualTo(1);
      assertThat(loader3.numInvocations).isEqualTo(1);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} does not allow loader with
     * next load position at end-of-source to continue loading.
     */
    @Test
    public void continueLoadingOnlyNotAllowEndOfSourceLoaderToLoad() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(
              /* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
      compositeSequenceableLoader.continueLoading(3000);
  
      assertThat(loader1.numInvocations).isEqualTo(0);
      assertThat(loader2.numInvocations).isEqualTo(0);
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} returns true if the loader
     * with minimum next load position can make progress if next load positions are not behind current
     * playback position.
     */
    @Test
    public void continueLoadingReturnTrueIfFurthestBehindLoaderCanMakeProgress() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
      loader1.setNextChunkDurationUs(1000);
  
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
  
      assertThat(compositeSequenceableLoader.continueLoading(100)).isTrue();
    }
  
    /**
     * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} returns true if any loader
     * that are behind current playback position can make progress, even if it is not the one with
     * minimum next load position.
     */
    @Test
    public void continueLoadingReturnTrueIfLoaderBehindPlaybackPositionCanMakeProgress() {
      FakeSequenceableLoader loader1 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
      FakeSequenceableLoader loader2 =
          new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
      // loader2 is not the furthest behind, but it can make progress if allowed.
      loader2.setNextChunkDurationUs(1000);
  
      CompositeSequenceableLoader compositeSequenceableLoader =
          new CompositeSequenceableLoader(new SequenceableLoader[] {loader1, loader2});
  
      assertThat(compositeSequenceableLoader.continueLoading(3000)).isTrue();
    }
  
    private static class FakeSequenceableLoader implements SequenceableLoader {
  
      private long bufferedPositionUs;
      private long nextLoadPositionUs;
      private int numInvocations;
      private int nextChunkDurationUs;
  
      private FakeSequenceableLoader(long bufferedPositionUs, long nextLoadPositionUs) {
        this.bufferedPositionUs = bufferedPositionUs;
        this.nextLoadPositionUs = nextLoadPositionUs;
      }
  
      @Override
      public long getBufferedPositionUs() {
        return bufferedPositionUs;
      }
  
      @Override
      public long getNextLoadPositionUs() {
        return nextLoadPositionUs;
      }
  
      @Override
      public boolean continueLoading(long positionUs) {
        numInvocations++;
        boolean loaded = nextChunkDurationUs != 0;
        // The current chunk has been loaded, advance to next chunk.
        bufferedPositionUs = nextLoadPositionUs;
        nextLoadPositionUs += nextChunkDurationUs;
        nextChunkDurationUs = 0;
        return loaded;
      }
  
      @Override
      public boolean isLoading() {
        return nextChunkDurationUs != 0;
      }
  
      @Override
      public void reevaluateBuffer(long positionUs) {
        // Do nothing.
      }
  
      private void setNextChunkDurationUs(int nextChunkDurationUs) {
        this.nextChunkDurationUs = nextChunkDurationUs;
      }
    }
  }
  