/*
 * Copyright (C) 2016 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.chunk;

import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.upstream.DataSource;
import com.google.android.exoplayer2.upstream.DataSpec;
import com.google.android.exoplayer2.upstream.Loader.Loadable;
import com.google.android.exoplayer2.util.Assertions;

/**
 * An abstract base class for {@link Loadable} implementations that load chunks of data required
 * for the playback of streams.
 */
public abstract class Chunk implements Loadable {

  /**
   * The {@link DataSpec} that defines the data to be loaded.
   */
  public final DataSpec dataSpec;
  /**
   * The type of the chunk. One of the {@code DATA_TYPE_*} constants defined in {@link C}. For
   * reporting only.
   */
  public final int type;
  /**
   * The format of the track to which this chunk belongs, or null if the chunk does not belong to
   * a track.
   */
  public final Format trackFormat;
  /**
   * One of the {@link C} {@code SELECTION_REASON_*} constants if the chunk belongs to a track.
   * {@link C#SELECTION_REASON_UNKNOWN} if the chunk does not belong to a track.
   */
  public final int trackSelectionReason;
  /**
   * Optional data associated with the selection of the track to which this chunk belongs. Null if
   * the chunk does not belong to a track.
   */
  public final Object trackSelectionData;
  /**
   * The start time of the media contained by the chunk, or {@link C#TIME_UNSET} if the data
   * being loaded does not contain media samples.
   */
  public final long startTimeUs;
  /**
   * The end time of the media contained by the chunk, or {@link C#TIME_UNSET} if the data being
   * loaded does not contain media samples.
   */
  public final long endTimeUs;

  protected final DataSource dataSource;

  /**
   * @param dataSource The source from which the data should be loaded.
   * @param dataSpec Defines the data to be loaded.
   * @param type See {@link #type}.
   * @param trackFormat See {@link #trackFormat}.
   * @param trackSelectionReason See {@link #trackSelectionReason}.
   * @param trackSelectionData See {@link #trackSelectionData}.
   * @param startTimeUs See {@link #startTimeUs}.
   * @param endTimeUs See {@link #endTimeUs}.
   */
  public Chunk(DataSource dataSource, DataSpec dataSpec, int type, Format trackFormat,
      int trackSelectionReason, Object trackSelectionData, long startTimeUs, long endTimeUs) {
    this.dataSource = Assertions.checkNotNull(dataSource);
    this.dataSpec = Assertions.checkNotNull(dataSpec);
    this.type = type;
    this.trackFormat = trackFormat;
    this.trackSelectionReason = trackSelectionReason;
    this.trackSelectionData = trackSelectionData;
    this.startTimeUs = startTimeUs;
    this.endTimeUs = endTimeUs;
  }

  /**
   * Returns the duration of the chunk in microseconds.
   */
  public final long getDurationUs() {
    return endTimeUs - startTimeUs;
  }

  /**
   * Returns the number of bytes that have been loaded.
   */
  public abstract long bytesLoaded();

}
