content: /*
   * Copyright (C) 2019 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 androidx.annotation.WorkerThread;
  import java.io.IOException;
  
  /** An index of {@link Download Downloads}. */
  @WorkerThread
  public interface DownloadIndex {
  
    /**
     * Returns the {@link Download} with the given {@code id}, or null.
     *
     * <p>This method may be slow and shouldn't normally be called on the main thread.
     *
     * @param id ID of a {@link Download}.
     * @return The {@link Download} with the given {@code id}, or null if a download state with this
     *     id doesn't exist.
     * @throws IOException If an error occurs reading the state.
     */
    @Nullable
    Download getDownload(String id) throws IOException;
  
    /**
     * Returns a {@link DownloadCursor} to {@link Download}s with the given {@code states}.
     *
     * <p>This method may be slow and shouldn't normally be called on the main thread.
     *
     * @param states Returns only the {@link Download}s with this states. If empty, returns all.
     * @return A cursor to {@link Download}s with the given {@code states}.
     * @throws IOException If an error occurs reading the state.
     */
    DownloadCursor getDownloads(@Download.State int... states) throws IOException;
  }
  