content: /*
   * 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 com.google.android.exoplayer2.upstream;
  
  import android.support.annotation.NonNull;
  import com.google.android.exoplayer2.C;
  import com.google.android.exoplayer2.util.Assertions;
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * Allows data corresponding to a given {@link DataSpec} to be read from a {@link DataSource} and
   * consumed through an {@link InputStream}.
   */
  public final class DataSourceInputStream extends InputStream {
  
    private final DataSource dataSource;
    private final DataSpec dataSpec;
    private final byte[] singleByteArray;
  
    private boolean opened = false;
    private boolean closed = false;
    private long totalBytesRead;
  
    /**
     * @param dataSource The {@link DataSource} from which the data should be read.
     * @param dataSpec The {@link DataSpec} defining the data to be read from {@code dataSource}.
     */
    public DataSourceInputStream(DataSource dataSource, DataSpec dataSpec) {
      this.dataSource = dataSource;
      this.dataSpec = dataSpec;
      singleByteArray = new byte[1];
    }
  
    /**
     * Returns the total number of bytes that have been read or skipped.
     */
    public long bytesRead() {
      return totalBytesRead;
    }
  
    /**
     * Optional call to open the underlying {@link DataSource}.
     * <p>
     * Calling this method does nothing if the {@link DataSource} is already open. Calling this
     * method is optional, since the read and skip methods will automatically open the underlying
     * {@link DataSource} if it's not open already.
     *
     * @throws IOException If an error occurs opening the {@link DataSource}.
     */
    public void open() throws IOException {
      checkOpened();
    }
  
    @Override
    public int read() throws IOException {
      int length = read(singleByteArray);
      return length == -1 ? -1 : (singleByteArray[0] & 0xFF);
    }
  
    @Override
    public int read(@NonNull byte[] buffer) throws IOException {
      return read(buffer, 0, buffer.length);
    }
  
    @Override
    public int read(@NonNull byte[] buffer, int offset, int length) throws IOException {
      Assertions.checkState(!closed);
      checkOpened();
      int bytesRead = dataSource.read(buffer, offset, length);
      if (bytesRead == C.RESULT_END_OF_INPUT) {
        return -1;
      } else {
        totalBytesRead += bytesRead;
        return bytesRead;
      }
    }
  
    @Override
    public void close() throws IOException {
      if (!closed) {
        dataSource.close();
        closed = true;
      }
    }
  
    private void checkOpened() throws IOException {
      if (!opened) {
        dataSource.open(dataSpec);
        opened = true;
      }
    }
  
  }
  