add support for large amount of programs

TV Player WPF/ViewModels/ProgramsListViewModel.cs

@@ -1,13 +1,18 @@
 using CommunityToolkit.Mvvm.Input;
+using System.Collections.ObjectModel;
+using System.Reactive.Linq;
+using System.Reactive;
 using System.Windows.Input;
 using TV_Player.ViewModels;
+using System.Windows;
+using System.Reactive.Concurrency;
 
 namespace TV_Player
 {
     public class ProgramsListViewModel : ObservableViewModelBase, IDisposable
     {
-        private List<M3UInfo> _programs;
-        public List<M3UInfo> Programs
+        private ObservableCollection<M3UInfo> _programs = new ObservableCollection<M3UInfo>();
+        public ObservableCollection<M3UInfo> Programs
         {
             get => _programs;
             set => SetProperty(ref _programs, value);
@@ -15,13 +20,17 @@ namespace TV_Player
 
         public M3UInfo SelectedItem { get; set; }
         public ICommand ItemSelectedCommand { get; }
-        private IDisposable _programSubscriber;
+        private CancellationTokenSource cts = new CancellationTokenSource();
 
-        public ProgramsListViewModel(string playlistName,GroupInfo groupInfo)
+
+        public ProgramsListViewModel(string playlistName, GroupInfo groupInfo)
         {
             TVPlayerViewModel.Instance.TopPanelVisible(true, groupInfo.Name);
             ItemSelectedCommand = new RelayCommand(OnItemSelected);
-            _programSubscriber = TVPlayerViewModel.Instance.CurrentProgrmsData.AllPrograms.Subscribe(x => Programs = x.Where(p => p.GroupTitle == groupInfo.Name).ToList());
+            //_programSubscriber = TVPlayerViewModel.Instance.CurrentProgrmsData.AllPrograms.Subscribe(x => Programs = x.Where(p => p.GroupTitle == groupInfo.Name));
+
+            SubscribeToProgramsData(groupInfo);
+
 
             TVPlayerViewModel.Instance.SetBackButtonAction(new Action(() =>
             {
@@ -29,6 +38,36 @@ namespace TV_Player
             }));
         }
 
+        private void SubscribeToProgramsData(GroupInfo groupInfo)
+        {
+             TVPlayerViewModel.Instance.CurrentProgrmsData.AllPrograms.ObserveOn(Scheduler.Default)
+                   .Subscribe(newPrograms =>
+                   {
+                       var filteredPrograms = newPrograms.Where(p => p.GroupTitle == groupInfo.Name).ToList();
+
+                       Programs.Clear();
+                       const int batchSize = 100; // Define the batch size
+                       int totalItems = filteredPrograms.Count;
+
+                       for (int i = 0; i < totalItems; i += batchSize)
+                       {
+                           // Take the next batch of 100 items
+                           var batch = filteredPrograms.Skip(i).Take(batchSize).ToList();
+                           Application.Current.Dispatcher.Invoke(() =>
+                           {
+                               // Add the batch to the collection
+                               foreach (var program in batch)
+                               {
+
+                                   Programs.Add(program);
+
+                               }
+                           });
+                           Task.Delay(500, cts.Token).Wait();
+                       }
+                   }, cts.Token);
+        }
+
         private void OnItemSelected()
         {
             TVPlayerViewModel.Instance.ShowPlayerScreen(SelectedItem);
@@ -36,7 +75,7 @@ namespace TV_Player
 
         public void Dispose()
         {
-            _programSubscriber.Dispose();
+            cts.Cancel();
         }
     }
 }