content: /*
   * Copyright (C) 2018 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.upstream;
  
  import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
  import static com.google.android.exoplayer2.util.Util.castNonNull;
  
  import androidx.annotation.Nullable;
  import java.util.ArrayList;
  
  /**
   * Base {@link DataSource} implementation to keep a list of {@link TransferListener}s.
   *
   * <p>Subclasses must call {@link #transferInitializing(DataSpec)}, {@link
   * #transferStarted(DataSpec)}, {@link #bytesTransferred(int)}, and {@link #transferEnded()} to
   * inform listeners of data transfers.
   */
  public abstract class BaseDataSource implements DataSource {
  
    private final boolean isNetwork;
    private final ArrayList<TransferListener> listeners;
  
    private int listenerCount;
    @Nullable private DataSpec dataSpec;
  
    /**
     * Creates base data source.
     *
     * @param isNetwork Whether the data source loads data through a network.
     */
    protected BaseDataSource(boolean isNetwork) {
      this.isNetwork = isNetwork;
      this.listeners = new ArrayList<>(/* initialCapacity= */ 1);
    }
  
    @Override
    public final void addTransferListener(TransferListener transferListener) {
      checkNotNull(transferListener);
      if (!listeners.contains(transferListener)) {
        listeners.add(transferListener);
        listenerCount++;
      }
    }
  
    /**
     * Notifies listeners that data transfer for the specified {@link DataSpec} is being initialized.
     *
     * @param dataSpec {@link DataSpec} describing the data for initializing transfer.
     */
    protected final void transferInitializing(DataSpec dataSpec) {
      for (int i = 0; i < listenerCount; i++) {
        listeners.get(i).onTransferInitializing(/* source= */ this, dataSpec, isNetwork);
      }
    }
  
    /**
     * Notifies listeners that data transfer for the specified {@link DataSpec} started.
     *
     * @param dataSpec {@link DataSpec} describing the data being transferred.
     */
    protected final void transferStarted(DataSpec dataSpec) {
      this.dataSpec = dataSpec;
      for (int i = 0; i < listenerCount; i++) {
        listeners.get(i).onTransferStart(/* source= */ this, dataSpec, isNetwork);
      }
    }
  
    /**
     * Notifies listeners that bytes were transferred.
     *
     * @param bytesTransferred The number of bytes transferred since the previous call to this method
     *     (or if the first call, since the transfer was started).
     */
    protected final void bytesTransferred(int bytesTransferred) {
      DataSpec dataSpec = castNonNull(this.dataSpec);
      for (int i = 0; i < listenerCount; i++) {
        listeners
            .get(i)
            .onBytesTransferred(/* source= */ this, dataSpec, isNetwork, bytesTransferred);
      }
    }
  
    /** Notifies listeners that a transfer ended. */
    protected final void transferEnded() {
      DataSpec dataSpec = castNonNull(this.dataSpec);
      for (int i = 0; i < listenerCount; i++) {
        listeners.get(i).onTransferEnd(/* source= */ this, dataSpec, isNetwork);
      }
      this.dataSpec = null;
    }
  }
  