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.net.Uri;
  import com.google.android.exoplayer2.C;
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.RandomAccessFile;
  
  /**
   * A {@link DataSource} for reading local files.
   */
  public final class FileDataSource implements DataSource {
  
    /**
     * Thrown when IOException is encountered during local file read operation.
     */
    public static class FileDataSourceException extends IOException {
  
      public FileDataSourceException(IOException cause) {
        super(cause);
      }
  
    }
  
    private final TransferListener<? super FileDataSource> listener;
  
    private RandomAccessFile file;
    private Uri uri;
    private long bytesRemaining;
    private boolean opened;
  
    public FileDataSource() {
      this(null);
    }
  
    /**
     * @param listener An optional listener.
     */
    public FileDataSource(TransferListener<? super FileDataSource> listener) {
      this.listener = listener;
    }
  
    @Override
    public long open(DataSpec dataSpec) throws FileDataSourceException {
      try {
        uri = dataSpec.uri;
        file = new RandomAccessFile(dataSpec.uri.getPath(), "r");
        file.seek(dataSpec.position);
        bytesRemaining = dataSpec.length == C.LENGTH_UNSET ? file.length() - dataSpec.position
            : dataSpec.length;
        if (bytesRemaining < 0) {
          throw new EOFException();
        }
      } catch (IOException e) {
        throw new FileDataSourceException(e);
      }
  
      opened = true;
      if (listener != null) {
        listener.onTransferStart(this, dataSpec);
      }
  
      return bytesRemaining;
    }
  
    @Override
    public int read(byte[] buffer, int offset, int readLength) throws FileDataSourceException {
      if (readLength == 0) {
        return 0;
      } else if (bytesRemaining == 0) {
        return C.RESULT_END_OF_INPUT;
      } else {
        int bytesRead;
        try {
          bytesRead = file.read(buffer, offset, (int) Math.min(bytesRemaining, readLength));
        } catch (IOException e) {
          throw new FileDataSourceException(e);
        }
  
        if (bytesRead > 0) {
          bytesRemaining -= bytesRead;
          if (listener != null) {
            listener.onBytesTransferred(this, bytesRead);
          }
        }
  
        return bytesRead;
      }
    }
  
    @Override
    public Uri getUri() {
      return uri;
    }
  
    @Override
    public void close() throws FileDataSourceException {
      uri = null;
      try {
        if (file != null) {
          file.close();
        }
      } catch (IOException e) {
        throw new FileDataSourceException(e);
      } finally {
        file = null;
        if (opened) {
          opened = false;
          if (listener != null) {
            listener.onTransferEnd(this);
          }
        }
      }
    }
  
  }
  