/*
 * 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.
 */

import 'dart:async';
import 'dart:io';
import 'dart:isolate';
import 'dart:typed_data';

import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart';
import 'package:test/test.dart';

class Message {
  Message(this.image, this.sendPort);

  final Uint8List image;
  final SendPort sendPort;
}

Future<Uint8List> download(String url) async {
  final HttpClient client = HttpClient();
  final HttpClientRequest request = await client.getUrl(Uri.parse(url));
  final HttpClientResponse response = await request.close();
  final BytesBuilder builder = await response.fold(
      BytesBuilder(), (BytesBuilder b, List<int> d) => b..add(d));
  final List<int> data = builder.takeBytes();
  return Uint8List.fromList(data);
}

void compute(Message message) {
  final Document pdf = Document();

  final PdfImage image = PdfImage.jpeg(
    pdf.document,
    image: message.image,
  );

  pdf.addPage(Page(build: (Context context) => Center(child: Image(image))));

  message.sendPort.send(pdf.save());
}

void main() {
  test('Pdf Isolate', () async {
    final Completer<void> completer = Completer<void>();
    final ReceivePort receivePort = ReceivePort();

    receivePort.listen((dynamic data) async {
      if (data is List<int>) {
        print('Received a ${data.length} bytes PDF');
        final File file = File('isolate.pdf');
        await file.writeAsBytes(data);
        print('File saved');
      }
      completer.complete();
    });

    print('Download image');
    final Uint8List imageBytes =
        await download('https://www.nfet.net/nfet.jpg');

    print('Generate PDF');
    await Isolate.spawn<Message>(
      compute,
      Message(imageBytes, receivePort.sendPort),
    );

    print('Wait PDF to be generated');
    await completer.future;
    print('Done');
  });
}