/*
 * Copyright (C) 2017, David PHAM-VAN <dev.nfet.net@gmail.com>
 *
 * 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.
 */

part of pdf;

class PdfObjectStream extends PdfObject {
  /// Constructs a stream. The supplied type is stored in the stream's header
  /// and is used by other objects that extend the [PdfStream] class (like
  /// [PdfImage]).
  /// By default, the stream will be compressed.
  ///
  /// @param type type for the stream
  /// @see [PdfImage]
  PdfObjectStream(PdfDocument pdfDocument, {String type, this.isBinary = false})
      : super(pdfDocument, type);

  /// This holds the stream's content.
  final PdfStream buf = PdfStream();

  /// defines if the stream needs to be converted to ascii85
  final bool isBinary;

  List<int> _data;

  @override
  void _prepare() {
    super._prepare();

    if (params.containsKey('/Filter')) {
      // The data is already in the right format
      _data = buf.output();
    } else if (pdfDocument.deflate != null) {
      _data = pdfDocument.deflate(buf.output());
      params['/Filter'] = PdfStream.string('/FlateDecode');
    } else if (isBinary) {
      // This is a Ascii85 stream
      final Ascii85Encoder e = Ascii85Encoder();
      _data = e.convert(buf.output());
      params['/Filter'] = PdfStream.string('/ASCII85Decode');
    } else {
      // This is a non-deflated stream
      _data = buf.output();
    }
    params['/Length'] = PdfStream.intNum(_data.length);
  }

  @override
  void _writeContent(PdfStream os) {
    super._writeContent(os);

    os.putString('stream\n');
    os.putBytes(_data);
    os.putString('\nendstream\n');
  }
}