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.offline;
  
  import androidx.annotation.Nullable;
  import com.google.android.exoplayer2.C;
  import java.io.IOException;
  import java.util.concurrent.CancellationException;
  
  /** Downloads and removes a piece of content. */
  public interface Downloader {
  
    /** Receives progress updates during download operations. */
    interface ProgressListener {
  
      /**
       * Called when progress is made during a download operation.
       *
       * <p>May be called directly from {@link #download}, or from any other thread used by the
       * downloader. In all cases, {@link #download} is guaranteed not to return until after the last
       * call to this method has finished executing.
       *
       * @param contentLength The length of the content in bytes, or {@link C#LENGTH_UNSET} if
       *     unknown.
       * @param bytesDownloaded The number of bytes that have been downloaded.
       * @param percentDownloaded The percentage of the content that has been downloaded, or {@link
       *     C#PERCENTAGE_UNSET}.
       */
      void onProgress(long contentLength, long bytesDownloaded, float percentDownloaded);
    }
  
    /**
     * Downloads the content.
     *
     * <p>If downloading fails, this method can be called again to resume the download. It cannot be
     * called again after the download has been {@link #cancel canceled}.
     *
     * <p>If downloading is canceled whilst this method is executing, then it is expected that it will
     * return reasonably quickly. However, there are no guarantees about how the method will return,
     * meaning that it can return without throwing, or by throwing any of its documented exceptions.
     * The caller must use its own knowledge about whether downloading has been canceled to determine
     * whether this is why the method has returned, rather than relying on the method returning in a
     * particular way.
     *
     * @param progressListener A listener to receive progress updates, or {@code null}.
     * @throws IOException If the download failed to complete successfully.
     * @throws InterruptedException If the download was interrupted.
     * @throws CancellationException If the download was canceled.
     */
    void download(@Nullable ProgressListener progressListener)
        throws IOException, InterruptedException;
  
    /**
     * Permanently cancels the downloading by this downloader. The caller should also interrupt the
     * downloading thread immediately after calling this method.
     *
     * <p>Once canceled, {@link #download} cannot be called again.
     */
    void cancel();
  
    /** Removes the content. */
    void remove();
  }
  