zhaw-dnet2/Tasks/Lab12/TodoDetails/ViewModel/TodosViewModel.cs

using CommunityToolkit.Mvvm.Input;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using TodoDetails.Model;
using TodoDetails.Services;
using TodoDetails.View;

namespace TodoDetails.ViewModel
{
    public partial class TodosViewModel : BaseViewModel
    {
        public ObservableCollection<Todo> Todos { get; } = new ObservableCollection<Todo>();
        TodoService todoService;

        public TodosViewModel(TodoService todoService)
        {
            Title = "Todos";
            this.todoService = todoService;
        }

        [RelayCommand]
        async Task GetTodosAsync()
        {
            if (IsBusy)
            {
                return;
            }

            try
            {
                IsBusy = true;
                var todos = await todoService.GetTodos();

                if (Todos.Count != 0)
                {
                    Todos.Clear();
                }

                foreach (var todo in todos)
                {
                    Todos.Add(todo);
                }
            }
            catch (Exception e)
            {
                Debug.WriteLine($"UInable to get todos: {e.Message}");
                await Shell.Current.DisplayAlert("Error!", e.Message, "OK");
            }
            finally
            {
                IsBusy = false;
            }
        }

        [RelayCommand]
        async Task GoToDetails(Todo todo)
        {
            if (todo == null)
            {
                return;
            }

            await Shell.Current.GoToAsync(
                nameof(TodoDetailsPage),
                true,
                new Dictionary<string, object>()
                {
                    { nameof(Todo), todo }
                });
        }
    }
}