/*
 * Copyright 2012 Google Inc.
 *
 * 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.api.client.googleapis.media;

import java.io.IOException;

/**
 * An interface for receiving progress notifications for downloads.
 *
 * <p>Sample usage:
 *
 * <pre>{@code
 * public static class MyDownloadProgressListener implements MediaHttpDownloaderProgressListener {
 *
 *   public void progressChanged(MediaHttpDownloader downloader) throws IOException {
 *     switch (downloader.getDownloadState()) {
 *       case MEDIA_IN_PROGRESS:
 *         System.out.println("Download in progress");
 *         System.out.println("Download percentage: " + downloader.getProgress());
 *         break;
 *       case MEDIA_COMPLETE:
 *         System.out.println("Download Completed!");
 *         break;
 *     }
 *   }
 * }
 * }</pre>
 *
 * @since 1.9
 * @author rmistry@google.com (Ravi Mistry)
 */
public interface MediaHttpDownloaderProgressListener {

  /**
   * Called to notify that progress has been changed.
   *
   * <p>This method is called multiple times depending on how many chunks are downloaded. Once the
   * download completes it is called one final time.
   *
   * <p>The download state can be queried by calling {@link MediaHttpDownloader#getDownloadState}
   * and the progress by calling {@link MediaHttpDownloader#getProgress}.
   *
   * @param downloader Media HTTP downloader
   */
  public void progressChanged(MediaHttpDownloader downloader) throws IOException;
}
