1using System;
 2using System.Collections.Generic;
 3using System.Collections.ObjectModel;
 4using System.ComponentModel;
 5using System.Linq;
 6using System.Linq.Expressions;
 7using System.Windows.Input;
 8using MVPtoMVVM.domain;
 9using MVPtoMVVM.repositories;
10
11namespace MVPtoMVVM.mvvm.viewmodels
12{
13    public class MainWindowViewModel : INotifyPropertyChanged
14    {
15        private ITodoItemRepository todoItemRepository;
16        private Synchronizer<MainWindowViewModel> updater;
17        public event PropertyChangedEventHandler PropertyChanged = (o, e) => { };
18        public ICollection<TodoItemViewModel> TodoItems { get; set; }
19        public ICommand CancelChangesCommand { get; set; }
20        public ICommand AddNewItemCommand { get; set; }
21
22        public MainWindowViewModel(ITodoItemRepository todoItemRepository)
23        {
24            this.todoItemRepository = todoItemRepository;
25            AddNewItemCommand = new SimpleCommand(AddNewItem);
26            CancelChangesCommand = new SimpleCommand(RefreshChanges);
27            updater = new Synchronizer<MainWindowViewModel>(() => PropertyChanged);
28            TodoItems = new ObservableCollection<TodoItemViewModel>();
29            RefreshChanges();
30        }
31
32        private void RefreshChanges()
33        {
34            TodoItems.Clear();
35            foreach (var item in todoItemRepository.GetAll().Select(MapFrom))
36            {
37                TodoItems.Add(item);
38            }
39        }
40
41        private void AddNewItem()
42        {
43            TodoItems.Add(new TodoItemViewModel(todoItemRepository){Parent =  this, DueDate = DateTime.Today, Description = string.Empty, IsDirty = false});
44        }
45
46        private TodoItemViewModel MapFrom(TodoItem item)
47        {
48            return new TodoItemViewModel(todoItemRepository)
49                       {
50                           Id = item.Id,
51                           Description =  item.Description,
52                           DueDate = item.DueDate,                                                                        
53                           Parent = this,
54                           IsDirty = false,
55                       };
56        }
57
58        public void Update(Expression<Func<MainWindowViewModel, object>> property)
59        {
60            updater.Update(this, property);
61        }
62    }
63}