Fix resume loading behavior

StabilityMatrix.Avalonia/ViewModels/DownloadProgressItemViewModel.cs

@@ -13,6 +13,7 @@ public class DownloadProgressItemViewModel : PausableProgressItemViewModelBase
     {
         this.download = download;
 
+        Id = download.Id;
         Name = download.FileName;
         State = download.ProgressState;
         

StabilityMatrix.Avalonia/ViewModels/MainWindowViewModel.cs

@@ -24,6 +24,7 @@ public partial class MainWindowViewModel : ViewModelBase
 {
     private readonly ISettingsManager settingsManager;
     private readonly ServiceManager<ViewModelBase> dialogFactory;
+    private readonly ITrackedDownloadService trackedDownloadService;
     private readonly IDiscordRichPresenceService discordRichPresenceService;
     public string Greeting => "Welcome to Avalonia!";
     
@@ -45,11 +46,13 @@ public partial class MainWindowViewModel : ViewModelBase
     public MainWindowViewModel(
         ISettingsManager settingsManager, 
         IDiscordRichPresenceService discordRichPresenceService,
+        ITrackedDownloadService trackedDownloadService,
         ServiceManager<ViewModelBase> dialogFactory)
     {
         this.settingsManager = settingsManager;
         this.dialogFactory = dialogFactory;
         this.discordRichPresenceService = discordRichPresenceService;
+        this.trackedDownloadService = trackedDownloadService;
         
         ProgressManagerViewModel = dialogFactory.Get<ProgressManagerViewModel>();
         UpdateViewModel = dialogFactory.Get<UpdateViewModel>();
@@ -81,6 +84,9 @@ public partial class MainWindowViewModel : ViewModelBase
         // Initialize Discord Rich Presence (this needs LibraryDir so is set here)
         discordRichPresenceService.UpdateState();
         
+        // Load in-progress downloads
+        ProgressManagerViewModel.AddDownloads(trackedDownloadService.Downloads);
+        
         // Index checkpoints if we dont have
         Task.Run(() => settingsManager.IndexCheckpoints()).SafeFireAndForget();
         

StabilityMatrix.Avalonia/ViewModels/ProgressManagerViewModel.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Linq;
 using Avalonia.Collections;
@@ -38,6 +39,19 @@ public partial class ProgressManagerViewModel : PageViewModelBase
         ProgressItems.Add(vm);
     }
 
+    public void AddDownloads(IEnumerable<TrackedDownload> downloads)
+    {
+        foreach (var download in downloads)
+        {
+            if (ProgressItems.Any(vm => vm.Id == download.Id))
+            {
+                continue;
+            }
+            var vm = new DownloadProgressItemViewModel(download);
+            ProgressItems.Add(vm);
+        }
+    }
+    
     public void StartEventListener()
     {
         EventManager.Instance.ProgressChanged += OnProgressChanged;

StabilityMatrix.Core/Models/TrackedDownload.cs

@@ -1,6 +1,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Text.Json.Serialization;
 using AsyncAwaitBestPractices;
+using NLog;
 using StabilityMatrix.Core.Helper;
 using StabilityMatrix.Core.Models.FileInterfaces;
 using StabilityMatrix.Core.Models.Progress;
@@ -16,6 +17,8 @@ public class TrackedDownloadProgressEventArgs : EventArgs
 
 public class TrackedDownload
 {
+    private static readonly Logger Logger = LogManager.GetCurrentClassLogger();
+    
     [JsonIgnore]
     private IDownloadService? downloadService;
     
@@ -128,6 +131,7 @@ public class TrackedDownload
         {
             throw new InvalidOperationException($"Download state must be inactive to start, not {ProgressState}");
         }
+        Logger.Debug("Starting download {Download}", FileName);
         
         EnsureDownloadService();
         
@@ -138,34 +142,59 @@ public class TrackedDownload
             .ContinueWith(OnDownloadTaskCompleted);
         
         ProgressState = ProgressState.Working;
+        OnProgressStateChanged(ProgressState);
     }
 
     public void Resume()
     {
-        if (ProgressState != ProgressState.Inactive) return;
+        if (ProgressState != ProgressState.Inactive)
+        {
+            Logger.Warn("Attempted to resume download {Download} but it is not paused ({State})", FileName, ProgressState);
+        }
+        Logger.Debug("Resuming download {Download}", FileName);
+        
+        // Read the temp file to get the current size
+        var tempSize = 0L;
+        
+        var tempFile = DownloadDirectory.JoinFile(TempFileName);
+        if (tempFile.Exists)
+        {
+            tempSize = tempFile.Info.Length;
+        }
         
         EnsureDownloadService();
         
         downloadCancellationTokenSource = new CancellationTokenSource();
         downloadPauseTokenSource = new CancellationTokenSource();
         
-        downloadTask = StartDownloadTask(0, AggregateCancellationTokenSource.Token)
+        downloadTask = StartDownloadTask(tempSize, AggregateCancellationTokenSource.Token)
             .ContinueWith(OnDownloadTaskCompleted);
         
         ProgressState = ProgressState.Working;
+        OnProgressStateChanged(ProgressState);
     }
 
     public void Pause()
     {
-        if (ProgressState != ProgressState.Working) return;
+        if (ProgressState != ProgressState.Working)
+        {
+            Logger.Warn("Attempted to pause download {Download} but it is not in progress ({State})", FileName, ProgressState);
+            return;
+        }
         
+        Logger.Debug("Pausing download {Download}", FileName);
         downloadPauseTokenSource?.Cancel();
     }
     
     public void Cancel()
     {
-        if (ProgressState is not (ProgressState.Working or ProgressState.Inactive)) return;
+        if (ProgressState is not (ProgressState.Working or ProgressState.Inactive))
+        {
+            Logger.Warn("Attempted to cancel download {Download} but it is not in progress ({State})", FileName, ProgressState);
+            return;
+        }
         
+        Logger.Debug("Cancelling download {Download}", FileName);
         downloadCancellationTokenSource?.Cancel();
     }
     

StabilityMatrix.Core/Services/ITrackedDownloadService.cs

@@ -5,6 +5,8 @@ namespace StabilityMatrix.Core.Services;
 
 public interface ITrackedDownloadService
 {
+    IEnumerable<TrackedDownload> Downloads { get; }
+    
     event EventHandler<TrackedDownload>? DownloadAdded;
     
     TrackedDownload NewDownload(Uri downloadUrl, FilePath downloadPath);

StabilityMatrix.Core/Services/TrackedDownloadService.cs

@@ -17,6 +17,8 @@ public class TrackedDownloadService : ITrackedDownloadService, IDisposable
     
     private readonly ConcurrentDictionary<Guid, (TrackedDownload, FileStream)> downloads = new();
 
+    public IEnumerable<TrackedDownload> Downloads => downloads.Values.Select(x => x.Item1);
+    
     /// <inheritdoc />
     public event EventHandler<TrackedDownload>? DownloadAdded;
     
@@ -136,6 +138,10 @@ public class TrackedDownloadService : ITrackedDownloadService, IDisposable
                 download.SetDownloadService(downloadService);
                 
                 downloads.TryAdd(download.Id, (download, fileStream));
+                
+                // Connect to state changed event to update json file
+                download.ProgressStateChanged += TrackedDownload_OnProgressStateChanged;
+                
                 OnDownloadAdded(download);
                 
                 logger.LogDebug("Loaded in-progress download {Download}", download.FileName);