todo-flutter/lib/providers/todoprovider.dart

import 'dart:convert';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:todoapp/elems/filehandler.dart';
import 'package:todoapp/elems/todo.dart';
import 'package:todoapp/elems/todolist.dart';
import 'package:todoapp/modules/todolistwidget.dart';
import 'package:todoapp/modules/todowidget.dart';

class TodoProvider extends ChangeNotifier {
  TodoProvider() {}

  Future<void> readListsFromDisk() async {
    Map js = await FileHandler.fileContent;

    for (String key in js.keys) {
      todoLists[key] =
          TodoList(title: key, widget: buildTodoListWidget(key), todos: []);

      Map decode = js[key];
      for (var key2 in decode.keys) {
        String title = key2;
        bool checked = decode[key2]["checked"];
        DateTime dueTime = DateTime.parse(decode[key2]["dueTime"]);
        bool notifiedDay = decode[key2]["notifiedDay"] ?? false;
        bool notifiedHour = decode[key2]["notifiedHour"] ?? false;
        todoLists[key]!.todos.add(Todo(
              title: title,
              widget: buildTodoWidget(title, checked, dueTime),
              checked: checked,
              dueTime: dueTime,
              notifiedDay: notifiedDay,
              notifiedHour: notifiedHour,
            ));
      }
    }

    todos = todoLists[selectedList]!.todos;

    notifyListeners();
  }

  Map<String, TodoList> todoLists = {};
  List<Todo> todos = [];
  String selectedList = "Personal";

  void renameList(String oldTitle, String newTitle) async {
    TodoList tempList = todoLists[oldTitle]!;
    tempList.title = newTitle;
    tempList.widget = buildTodoListWidget(newTitle);
    todoLists.remove(oldTitle);
    todoLists[newTitle] = tempList;
    selectedList = newTitle;
    todos = todoLists[newTitle]!.todos;

    await FileHandler.renameList(oldTitle, newTitle);

    notifyListeners();
  }

  void removeList(String title) async {
    todoLists.remove(title);
    selectedList = "Personal";
    todos = todoLists["Personal"]!.todos;

    await FileHandler.removeList(title);

    notifyListeners();
  }

  void addList(String title) async {
    TodoList list =
        TodoList(title: title, widget: buildTodoListWidget(title), todos: []);
    todoLists[title] = list;

    await FileHandler.addList(title);

    notifyListeners();
  }

  void changeList(String title) {
    if (!todoLists.containsKey(title)) {
      return;
    }

    selectedList = title;
    todos = todoLists[title]!.todos;
    notifyListeners();
  }

  Future<void> writeTodoChanges() async {
    Map js = {};

    for (Todo t in todos) {
      js["${t.title}"] = {
        "checked": t.checked,
        "dueTime": t.dueTime.toString(),
        "notifiedDay": t.notifiedDay,
        "notifiedHour": t.notifiedHour
      };
    }
    await FileHandler.saveList(js, selectedList);
  }

  void addTodo(String title, DateTime dueTime) async {
    todos.add(Todo(
        title: title,
        checked: false,
        widget: buildTodoWidget(title, false, dueTime),
        dueTime: dueTime,
        notifiedHour: false,
        notifiedDay: false));

    await writeTodoChanges();
    notifyListeners();
  }

  void removeTodo(String title) async {
    Todo todo = todoByTitle(title);
    todos.remove(todo);

    await writeTodoChanges();
    notifyListeners();
  }

  void updateTodo(String oldTitle, String newTitle, DateTime dueTime) async {
    Todo todo = todoByTitle(oldTitle);
    todo.title = newTitle;
    todo.dueTime = dueTime;
    todo.notifiedDay = false;
    todo.notifiedHour = false;

    todo.widget = buildTodoWidget(newTitle, todo.checked, dueTime);

    await writeTodoChanges();
    notifyListeners();
  }

  void setTodoState(String title, bool checked) async {
    Todo todo = todoByTitle(title);

    todo.checked = checked;
    todo.widget = buildTodoWidget(title, checked, todo.dueTime);

    await writeTodoChanges();
    notifyListeners();
  }

  TodoListWidget buildTodoListWidget(String title) {
    return TodoListWidget(title: title);
  }

  TodoWidget buildTodoWidget(String title, bool checked, DateTime dueTime) {
    return TodoWidget(checked: checked, title: title, dueTime: dueTime);
  }

  Todo todoByTitle(String title) {
    for (Todo t in todos) {
      if (t.title == title) {
        return t;
      }
    }
    return Todo(
        title: "None",
        widget: const SizedBox(),
        checked: false,
        dueTime: DateTime.now(),
        notifiedDay: false,
        notifiedHour: false,
    );
  }
}