/*
 * 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 androidx.media3.exoplayer.source.chunk;

import android.net.Uri;
import androidx.annotation.Nullable;
import androidx.media3.common.C;
import androidx.media3.common.C.DataType;
import androidx.media3.common.Format;
import androidx.media3.common.util.Assertions;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.datasource.DataSource;
import androidx.media3.datasource.DataSpec;
import androidx.media3.datasource.StatsDataSource;
import androidx.media3.exoplayer.source.LoadEventInfo;
import androidx.media3.exoplayer.upstream.Loader.Loadable;
import java.util.List;
import java.util.Map;

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

  /** Identifies the load task for this loadable. */
  public final long loadTaskId;

  /** The {@link DataSpec} that defines the data to be loaded. */
  public final DataSpec dataSpec;

  /** The {@link DataType data type} of the chunk. For reporting only. */
  public final @DataType int type;

  /** The format of the track to which this chunk belongs. */
  public final Format trackFormat;

  /**
   * One of the {@link C.SelectionReason selection reasons} if the chunk belongs to a track. {@link
   * C#SELECTION_REASON_UNKNOWN} if the chunk does not belong to a track, or if the selection reason
   * is unknown.
   */
  public final @C.SelectionReason 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, or if there is no associated track selection data.
   */
  @Nullable 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 StatsDataSource 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,
      @DataType int type,
      Format trackFormat,
      @C.SelectionReason int trackSelectionReason,
      @Nullable Object trackSelectionData,
      long startTimeUs,
      long endTimeUs) {
    this.dataSource = new StatsDataSource(dataSource);
    this.dataSpec = Assertions.checkNotNull(dataSpec);
    this.type = type;
    this.trackFormat = trackFormat;
    this.trackSelectionReason = trackSelectionReason;
    this.trackSelectionData = trackSelectionData;
    this.startTimeUs = startTimeUs;
    this.endTimeUs = endTimeUs;
    loadTaskId = LoadEventInfo.getNewId();
  }

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

  /**
   * Returns the number of bytes that have been loaded. Must only be called after the load
   * completed, failed, or was canceled.
   */
  public final long bytesLoaded() {
    return dataSource.getBytesRead();
  }

  /**
   * Returns the {@link Uri} associated with the last {@link DataSource#open} call. If redirection
   * occurred, this is the redirected uri. Must only be called after the load completed, failed, or
   * was canceled.
   *
   * @see DataSource#getUri()
   */
  public final Uri getUri() {
    return dataSource.getLastOpenedUri();
  }

  /**
   * Returns the response headers associated with the last {@link DataSource#open} call. Must only
   * be called after the load completed, failed, or was canceled.
   *
   * @see DataSource#getResponseHeaders()
   */
  public final Map<String, List<String>> getResponseHeaders() {
    return dataSource.getLastResponseHeaders();
  }
}