kmpdfkit_demo/example/lib/states/convert_task_queue_provider.dart

///  convert_task_queue_provider.dart
///  Copyright © 2014-2023 PDF Technologies, Inc. All Rights Reserved.
///
///  THIS SOURCE CODE AND ANY ACCOMPANYING DOCUMENTATION ARE PROTECTED BY INTERNATIONAL COPYRIGHT LAW
///  AND MAY NOT BE RESOLD OR REDISTRIBUTED. USAGE IS BOUND TO THE ComPDFKit LICENSE AGREEMENT.
///  UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS SUBJECT TO CIVIL AND CRIMINAL PENALTIES.
///  This notice may not be removed from this file.

import 'package:flutter/material.dart';
import 'package:kmpdfkit_conversion_flutter/cpdf_converter.dart';
import 'package:kmpdfkit_conversion_flutter/models/convert_type.dart';
import 'package:kmpdfkit_conversion_flutter/models/options/options.dart';
import 'package:kmpdfkit_conversion_flutter/models/task_result.dart';
import 'package:kmpdfkit_conversion_flutter/models/task_status.dart';
import 'package:kmpdfkit_conversion_flutter/util/string_extensions.dart';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';
import 'package:uuid/uuid.dart';

import '../models/convert_task.dart';

class ConvertTaskQueueProvider extends ChangeNotifier {
  final List<ConvertTask> _taskQueue = [];

  List<ConvertTask> get taskQueue => _taskQueue;

  bool _isExecuting = false;

  //Whether to automatically start executing the conversion task after the task is added to the list
  bool autoTask = true;

  /// add convert task to list
  void addTask(ConvertType convertType, Options options, List<String> files,
      String outputDir) {
    if (files.isEmpty) {
      conversionLog("pdf files is empty");
      return;
    }
    for (var i = 0; i < files.length; i++) {
      String? path = files[i];
      var taskId = const Uuid().v4();
      ConvertTask task = ConvertTask(
          taskId: taskId,
          filePath: path,
          fileName: p.basenameWithoutExtension(path),
          convertType: convertType,
          status: TaskStatus.wait,
          progress: 0,
          options: options,
          outputPath: outputDir);
      _taskQueue.add(task);
      conversionLog("The task has been added to the queue");
    }

    if (!_isExecuting && autoTask) {
      conversionLog(
          "There is no task in progress, and the conversion task is started");
      executeNextTask();
    }
    notifyListeners();
  }

  void executeNextTask() {
    ConvertTask? nextTask = getNextTask();
    if (nextTask != null) {
      conversionLog(
          "The waiting task in the queue is not empty, and the file transfer is started");
      startTask(nextTask);
    } else {
      conversionLog(
          "There is no waiting transfer task in the queue, and the task ends");
    }
  }

  void startTask(ConvertTask task) {
    _isExecuting = true;
    CPDFConverter.convert(
        taskId: task.taskId,
        filePath: task.filePath,
        convertType: task.convertType,
        outputPath: task.outputPath,
        options: task.options,
        callback: (TaskResult result) {
          conversionLog(
              "converting : taskId:${result.taskId}--progress:${result.progress}, status:${result.taskStatus}");
          updateStatus(result.taskId, result.progress, result.taskStatus,
              result.outPutPath);
          if (result.taskStatus == TaskStatus.success ||
              result.taskStatus == TaskStatus.fail) {
            conversionLog(
                "convert:${result.taskStatus.name}, start the next task");
            _isExecuting = false;
            if (autoTask) {
              executeNextTask();
            }
          }
        });
  }

  //Update the progress of the current conversion task

  void updateStatus(
      String taskId, int progress, TaskStatus status, String? outputPath) {
    ConvertTask bean =
        _taskQueue.firstWhere((element) => element.taskId == taskId);
    bean
      ..status = status
      ..progress = progress
      ..outputPath = outputPath ?? "";
    notifyListeners();
  }

  ConvertTask? getNextTask() {
    try {
      if (_taskQueue.any((element) => element.status == TaskStatus.wait)) {
        return _taskQueue
            .firstWhere((element) => element.status == TaskStatus.wait);
      } else {
        return null;
      }
    } catch (e) {
      return null;
    }
  }

  Future<String?> getOutputDir() async {
    var directory = await getApplicationSupportDirectory();
    return p.join(directory.path, "ConPDFKitConversion");
  }
}