refactor: Better ProgressBar code

- Uses Rx
- Doesn't require threads/locking
- Cleans up analysis issues

src/Common/ProgressBar.cs

@@ -1,113 +1,62 @@
 using System;
-using System.Diagnostics.CodeAnalysis;
+using System.Reactive.Linq;
+using System.Reactive.Subjects;
 using System.Text;
-using System.Threading;
 
 namespace Common;
 
 /// <summary>
 ///     An ASCII progress bar
 /// </summary>
-/// <remarks>
+public sealed class ProgressBar //: IProgress<double>
-///     Full credit to: https://gist.github.com/DanielSWolf/0ab6a96899cc5377bf54
-/// </remarks>
-[SuppressMessage("Reliability", "CA2002:Do not lock on objects with weak identity",
-    Justification = "Code is from third party")]
-public sealed class ProgressBar : IDisposable, IProgress<double>
 {
-    private const int BlockCount = 10;
     private readonly TimeSpan _animationInterval = TimeSpan.FromSeconds(1.0 / 8);
     private const string Animation = @"|/-\";
-
-    private readonly Timer _timer;
-
-    private double _currentProgress;
-    private string _currentText = string.Empty;
-    private bool _disposed;
     private int _animationIndex;
 
+    private readonly Subject<float> _reportProgress = new();
+    public IObserver<float> ReportProgress => _reportProgress;
+    public string Description { get; set; } = "";
+
     public ProgressBar()
     {
-        _timer = new Timer(TimerHandler);
-
         // A progress bar is only for temporary display in a console window.
         // If the console output is redirected to a file, draw nothing.
         // Otherwise, we'll end up with a lot of garbage in the target file.
         if (!Console.IsOutputRedirected)
         {
-            ResetTimer();
+            _reportProgress.Sample(_animationInterval)
+                .Select(CalculateText)
+                .StartWith(string.Empty)
+                .Buffer(2, 1) // sliding window: take previous and current
+                .Subscribe(x => UpdateText(x[0].Length, x[1]));
         }
     }
 
-    public void Report(double value)
+    private string CalculateText(float progress)
-    {
-        // Make sure value is in [0..1] range
-        value = Math.Max(0, Math.Min(1, value));
-        Interlocked.Exchange(ref _currentProgress, value);
-    }
-
-    private void TimerHandler(object? state)
     {
-        lock (_timer)
+        const int blockCount = 10;
-        {
+        var progressBlockCount = (int) (progress * blockCount);
-            if (_disposed)
+        var percent = (int) (progress * 100);
-            {
-                return;
-            }
-
-            var progressBlockCount = (int) (_currentProgress * BlockCount);
-            var percent = (int) (_currentProgress * 100);
         var progressBlocks = new string('#', progressBlockCount);
-            var progressBlocksUnfilled = new string('-', BlockCount - progressBlockCount);
+        var progressBlocksUnfilled = new string('-', blockCount - progressBlockCount);
         var currentAnimationFrame = Animation[_animationIndex++ % Animation.Length];
-            var text = $"[{progressBlocks}{progressBlocksUnfilled}] {percent,3}% {currentAnimationFrame}";
+        return $"[{progressBlocks}{progressBlocksUnfilled}] {percent,3}% {currentAnimationFrame} {Description}";
-            UpdateText(text);
-
-            ResetTimer();
-        }
     }
 
-    private void UpdateText(string text)
+    private static void UpdateText(int previousTextLength, string text)
     {
-        // Get length of common portion
-        var commonPrefixLength = 0;
-        var commonLength = Math.Min(_currentText.Length, text.Length);
-        while (commonPrefixLength < commonLength && text[commonPrefixLength] == _currentText[commonPrefixLength])
-        {
-            commonPrefixLength++;
-        }
-
-        // Backtrack to the first differing character
         var outputBuilder = new StringBuilder();
-        outputBuilder.Append('\b', _currentText.Length - commonPrefixLength);
+        outputBuilder.Append('\r');
+        outputBuilder.Append(text);
 
-        // Output new suffix
+        // If the previous string was longer, "erase" the old characters with spaces.
-        outputBuilder.Append(text.AsSpan(commonPrefixLength));
+        var lengthDifference = previousTextLength - text.Length;
-
+        if (lengthDifference > 0)
-        // If the new text is shorter than the old one: delete overlapping characters
-        var overlapCount = _currentText.Length - text.Length;
-        if (overlapCount > 0)
         {
-            outputBuilder.Append(' ', overlapCount);
+            outputBuilder.Append(' ', lengthDifference);
-            outputBuilder.Append('\b', overlapCount);
         }
 
         Console.Write(outputBuilder);
-        _currentText = text;
-    }
-
-    private void ResetTimer()
-    {
-        _timer.Change(_animationInterval, TimeSpan.FromMilliseconds(-1));
-    }
-
-    public void Dispose()
-    {
-        lock (_timer)
-        {
-            _disposed = true;
-            UpdateText(string.Empty);
-            _timer.Dispose();
-        }
     }
 }

src/VersionControl/GitRepositoryFactory.cs

@@ -35,17 +35,18 @@ public class GitRepositoryFactory : IGitRepositoryFactory
     {
         _fileUtils.DeleteReadOnlyDirectory(repoPath);
 
-        Console.Write("Requesting and parsing guide markdown ");
+        var progress = new ProgressBar
+        {
+            Description = "Requesting and parsing guide markdown"
+        };
 
-        using var progress = new ProgressBar();
         _staticWrapper.Clone(repoUrl, repoPath, new CloneOptions
         {
             RecurseSubmodules = false,
             BranchName = branch,
             OnTransferProgress = gitProgress =>
             {
-                // ReSharper disable once AccessToDisposedClosure
+                progress.ReportProgress.OnNext((float) gitProgress.ReceivedObjects / gitProgress.TotalObjects);
-                progress.Report((float) gitProgress.ReceivedObjects / gitProgress.TotalObjects);
                 return true;
             }
         });