/*
 * 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 androidx.media3.common.util.UnstableApi;
import androidx.media3.exoplayer.LoadingInfo;
import androidx.media3.exoplayer.SeekParameters;
import androidx.media3.exoplayer.upstream.LoadErrorHandlingPolicy;
import java.io.IOException;
import java.util.List;

/** A provider of {@link Chunk}s for a {@link ChunkSampleStream} to load. */
@UnstableApi
public interface ChunkSource {

  /**
   * Adjusts a seek position given the specified {@link SeekParameters}. Chunk boundaries are used
   * as sync points.
   *
   * @param positionUs The seek position in microseconds.
   * @param seekParameters Parameters that control how the seek is performed.
   * @return The adjusted seek position, in microseconds.
   */
  long getAdjustedSeekPositionUs(long positionUs, SeekParameters seekParameters);

  /**
   * If the source is currently having difficulty providing chunks, then this method throws the
   * underlying error. Otherwise does nothing.
   *
   * @throws IOException The underlying error.
   */
  void maybeThrowError() throws IOException;

  /**
   * Evaluates whether {@link MediaChunk}s should be removed from the back of the queue.
   *
   * <p>Removing {@link MediaChunk}s from the back of the queue can be useful if they could be
   * replaced with chunks of a significantly higher quality (e.g. because the available bandwidth
   * has substantially increased).
   *
   * <p>Will only be called if no {@link MediaChunk} in the queue is currently loading.
   *
   * @param playbackPositionUs The current playback position, in microseconds.
   * @param queue The queue of buffered {@link MediaChunk}s.
   * @return The preferred queue size.
   */
  int getPreferredQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue);

  /**
   * Returns whether an ongoing load of a chunk should be canceled.
   *
   * @param playbackPositionUs The current playback position, in microseconds.
   * @param loadingChunk The currently loading {@link Chunk}.
   * @param queue The queue of buffered {@link MediaChunk MediaChunks}.
   * @return Whether the ongoing load of {@code loadingChunk} should be canceled.
   */
  boolean shouldCancelLoad(
      long playbackPositionUs, Chunk loadingChunk, List<? extends MediaChunk> queue);

  /**
   * Returns the next chunk to load.
   *
   * <p>If a chunk is available then {@link ChunkHolder#chunk} is set. If the end of the stream has
   * been reached then {@link ChunkHolder#endOfStream} is set. If a chunk is not available but the
   * end of the stream has not been reached, the {@link ChunkHolder} is not modified.
   *
   * @param loadingInfo The {@link LoadingInfo} when loading request is made.
   * @param loadPositionUs The current load position in microseconds. If {@code queue} is empty,
   *     this is the starting position from which chunks should be provided. Else it's equal to
   *     {@link MediaChunk#endTimeUs} of the last chunk in the {@code queue}.
   * @param queue The queue of buffered {@link MediaChunk}s.
   * @param out A holder to populate.
   */
  void getNextChunk(
      LoadingInfo loadingInfo,
      long loadPositionUs,
      List<? extends MediaChunk> queue,
      ChunkHolder out);

  /**
   * Called when the {@link ChunkSampleStream} has finished loading a chunk obtained from this
   * source.
   *
   * @param chunk The chunk whose load has been completed.
   */
  void onChunkLoadCompleted(Chunk chunk);

  /**
   * Called when the {@link ChunkSampleStream} encounters an error loading a chunk obtained from
   * this source.
   *
   * @param chunk The chunk whose load encountered the error.
   * @param cancelable Whether the load can be canceled.
   * @param loadErrorInfo The load error info.
   * @param loadErrorHandlingPolicy The load error handling policy to customize the behaviour of
   *     handling the load error.
   * @return Whether the load should be canceled so that a replacement chunk can be loaded instead.
   *     Must be {@code false} if {@code cancelable} is {@code false}. If {@code true}, {@link
   *     #getNextChunk(LoadingInfo, long, List, ChunkHolder)} will be called to obtain the
   *     replacement chunk.
   */
  boolean onChunkLoadError(
      Chunk chunk,
      boolean cancelable,
      LoadErrorHandlingPolicy.LoadErrorInfo loadErrorInfo,
      LoadErrorHandlingPolicy loadErrorHandlingPolicy);

  /** Releases any held resources. */
  void release();
}