initial commit

Gallery.Share/ViewModels/ItemsViewModel.cs

@@ -0,0 +1,86 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+using System.Threading.Tasks;
+
+using Xamarin.Forms;
+
+using Gallery.Models;
+using Gallery.Views;
+
+namespace Gallery.ViewModels
+{
+    public class ItemsViewModel : BaseViewModel
+    {
+        private Item _selectedItem;
+
+        public ObservableCollection<Item> Items { get; }
+        public Command LoadItemsCommand { get; }
+        public Command AddItemCommand { get; }
+        public Command<Item> ItemTapped { get; }
+
+        public ItemsViewModel()
+        {
+            Title = "Browse";
+            Items = new ObservableCollection<Item>();
+            LoadItemsCommand = new Command(async () => await ExecuteLoadItemsCommand());
+
+            ItemTapped = new Command<Item>(OnItemSelected);
+
+            AddItemCommand = new Command(OnAddItem);
+        }
+
+        async Task ExecuteLoadItemsCommand()
+        {
+            IsBusy = true;
+
+            try
+            {
+                Items.Clear();
+                var items = await DataStore.GetItemsAsync(true);
+                foreach (var item in items)
+                {
+                    Items.Add(item);
+                }
+            }
+            catch (Exception ex)
+            {
+                Debug.WriteLine(ex);
+            }
+            finally
+            {
+                IsBusy = false;
+            }
+        }
+
+        public void OnAppearing()
+        {
+            IsBusy = true;
+            SelectedItem = null;
+        }
+
+        public Item SelectedItem
+        {
+            get => _selectedItem;
+            set
+            {
+                SetProperty(ref _selectedItem, value);
+                OnItemSelected(value);
+            }
+        }
+
+        private async void OnAddItem(object obj)
+        {
+            await Shell.Current.GoToAsync(nameof(NewItemPage));
+        }
+
+        async void OnItemSelected(Item item)
+        {
+            if (item == null)
+                return;
+
+            // This will push the ItemDetailPage onto the navigation stack
+            await Shell.Current.GoToAsync($"{nameof(ItemDetailPage)}?{nameof(ItemDetailViewModel.ItemId)}={item.Id}");
+        }
+    }
+}