//method called when Edit button is clicked
        private void btnEdit_Click(object sender, EventArgs e)
        {
            //check if any task is selected
            if (lvTasks.SelectedItems.Count == 0)
            {
                //if nothing is selected, show error
                MessageBox.Show("Select some task first", "Info", MessageBoxButtons.OK);
            }
            else
            {
                //get id of selected task - tha same way as when removing
                string taskId = lvTasks.SelectedItems[0].SubItems[0].Text;
                //find task by id
                TodoTask task = _todoTaskManager.FindTask(int.Parse(taskId));
                //display form and pass the task
                TaskDetails detailsForm = new TaskDetails(task);
                detailsForm.ShowDialog();

                //if task has been modified
                if (detailsForm.IsSaved)
                {
                    //update tasks in the file
                    _todoTaskManager.UpdateUserTasks(_logged.Id);
                    //update title and is finished
                    lvTasks.SelectedItems[0].SubItems[1].Text = task.Title;
                    lvTasks.SelectedItems[0].SubItems[2].Text = task.IsFinished ? "✓" : "✕";
                }
            }
        }
        //method called when Add button is clicked
        private void btnAdd_Click(object sender, EventArgs e)
        {
            //determine new task id
            int id = _todoTaskManager.GetNextId();
            //create task with new id and user id
            //title and description is empty yet
            TodoTask newTask = new TodoTask(id, _logged.Id, "", "");
            //create form with task details
            TaskDetails detailsForm = new TaskDetails(newTask);

            //show form as the dialog
            detailsForm.ShowDialog();

            //when dialog is closed check, if tash has been saved
            if (detailsForm.IsSaved)
            {
                //if so, add task to the list
                _todoTaskManager.AddTask(newTask);
                //and display it
                AddTaskToList(newTask);
            }
        }