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.content.Context;
  import android.content.res.AssetFileDescriptor;
  import android.content.res.Resources;
  import android.net.Uri;
  import android.text.TextUtils;
  import com.google.android.exoplayer2.C;
  import java.io.EOFException;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * A {@link DataSource} for reading a raw resource inside the APK.
   * <p>
   * URIs supported by this source are of the form {@code rawresource:///rawResourceId}, where
   * rawResourceId is the integer identifier of a raw resource. {@link #buildRawResourceUri(int)} can
   * be used to build {@link Uri}s in this format.
   */
  public final class RawResourceDataSource implements DataSource {
  
    /**
     * Thrown when an {@link IOException} is encountered reading from a raw resource.
     */
    public static class RawResourceDataSourceException extends IOException {
      public RawResourceDataSourceException(String message) {
        super(message);
      }
  
      public RawResourceDataSourceException(IOException e) {
        super(e);
      }
    }
  
    /**
     * Builds a {@link Uri} for the specified raw resource identifier.
     *
     * @param rawResourceId A raw resource identifier (i.e. a constant defined in {@code R.raw}).
     * @return The corresponding {@link Uri}.
     */
    public static Uri buildRawResourceUri(int rawResourceId) {
      return Uri.parse(RAW_RESOURCE_SCHEME + ":///" + rawResourceId);
    }
  
    /** The scheme part of a raw resource URI. */
    public static final String RAW_RESOURCE_SCHEME = "rawresource";
  
    private final Resources resources;
    private final TransferListener<? super RawResourceDataSource> listener;
  
    private Uri uri;
    private AssetFileDescriptor assetFileDescriptor;
    private InputStream inputStream;
    private long bytesRemaining;
    private boolean opened;
  
    /**
     * @param context A context.
     */
    public RawResourceDataSource(Context context) {
      this(context, null);
    }
  
    /**
     * @param context A context.
     * @param listener An optional listener.
     */
    public RawResourceDataSource(Context context,
        TransferListener<? super RawResourceDataSource> listener) {
      this.resources = context.getResources();
      this.listener = listener;
    }
  
    @Override
    public long open(DataSpec dataSpec) throws RawResourceDataSourceException {
      try {
        uri = dataSpec.uri;
        if (!TextUtils.equals(RAW_RESOURCE_SCHEME, uri.getScheme())) {
          throw new RawResourceDataSourceException("URI must use scheme " + RAW_RESOURCE_SCHEME);
        }
  
        int resourceId;
        try {
          resourceId = Integer.parseInt(uri.getLastPathSegment());
        } catch (NumberFormatException e) {
          throw new RawResourceDataSourceException("Resource identifier must be an integer.");
        }
  
        assetFileDescriptor = resources.openRawResourceFd(resourceId);
        inputStream = new FileInputStream(assetFileDescriptor.getFileDescriptor());
        inputStream.skip(assetFileDescriptor.getStartOffset());
        long skipped = inputStream.skip(dataSpec.position);
        if (skipped < dataSpec.position) {
          // We expect the skip to be satisfied in full. If it isn't then we're probably trying to
          // skip beyond the end of the data.
          throw new EOFException();
        }
        if (dataSpec.length != C.LENGTH_UNSET) {
          bytesRemaining = dataSpec.length;
        } else {
          long assetFileDescriptorLength = assetFileDescriptor.getLength();
          // If the length is UNKNOWN_LENGTH then the asset extends to the end of the file.
          bytesRemaining = assetFileDescriptorLength == AssetFileDescriptor.UNKNOWN_LENGTH
              ? C.LENGTH_UNSET : (assetFileDescriptorLength - dataSpec.position);
        }
      } catch (IOException e) {
        throw new RawResourceDataSourceException(e);
      }
  
      opened = true;
      if (listener != null) {
        listener.onTransferStart(this, dataSpec);
      }
  
      return bytesRemaining;
    }
  
    @Override
    public int read(byte[] buffer, int offset, int readLength) throws RawResourceDataSourceException {
      if (readLength == 0) {
        return 0;
      } else if (bytesRemaining == 0) {
        return C.RESULT_END_OF_INPUT;
      }
  
      int bytesRead;
      try {
        int bytesToRead = bytesRemaining == C.LENGTH_UNSET ? readLength
            : (int) Math.min(bytesRemaining, readLength);
        bytesRead = inputStream.read(buffer, offset, bytesToRead);
      } catch (IOException e) {
        throw new RawResourceDataSourceException(e);
      }
  
      if (bytesRead == -1) {
        if (bytesRemaining != C.LENGTH_UNSET) {
          // End of stream reached having not read sufficient data.
          throw new RawResourceDataSourceException(new EOFException());
        }
        return C.RESULT_END_OF_INPUT;
      }
      if (bytesRemaining != C.LENGTH_UNSET) {
        bytesRemaining -= bytesRead;
      }
      if (listener != null) {
        listener.onBytesTransferred(this, bytesRead);
      }
      return bytesRead;
    }
  
    @Override
    public Uri getUri() {
      return uri;
    }
  
    @Override
    public void close() throws RawResourceDataSourceException {
      uri = null;
      try {
        if (inputStream != null) {
          inputStream.close();
        }
      } catch (IOException e) {
        throw new RawResourceDataSourceException(e);
      } finally {
        inputStream = null;
        try {
          if (assetFileDescriptor != null) {
            assetFileDescriptor.close();
          }
        } catch (IOException e) {
          throw new RawResourceDataSourceException(e);
        } finally {
          assetFileDescriptor = null;
          if (opened) {
            opened = false;
            if (listener != null) {
              listener.onTransferEnd(this);
            }
          }
        }
      }
    }
  
  }
  