From a651720d08705c0d0c0e5078814fd7c54a5d5736 Mon Sep 17 00:00:00 2001
From: Katter <narcat99@gmail.com>
Date: Sat, 24 Aug 2024 21:28:36 +0500
Subject: [PATCH] Optimize (?) ScreenshotsLibrary.ClearExceed

---
 SightKeeper.Domain/Extensions.cs              | 27 +++++++++++++++++++
 .../Screenshots/ScreenshotsLibrary.cs         | 21 ++++++++++-----
 2 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/SightKeeper.Domain/Extensions.cs b/SightKeeper.Domain/Extensions.cs
index fadb61d8..0dca8648 100644
--- a/SightKeeper.Domain/Extensions.cs
+++ b/SightKeeper.Domain/Extensions.cs
@@ -17,4 +17,31 @@ public static ImmutableHashSet<T> ToImmutableHashSetThrowOnDuplicate<T>(this IEn
 		Guard.IsTrue(enumerable.All(tagsBuilder.Add));
 		return tagsBuilder.ToImmutable();
 	}
+
+	public static IEnumerable<(ImmutableArray<T>, int start, int end)> ToRanges<T>(this IEnumerable<T> enumerable, Func<T, int> indexSelector)
+	{
+		using var enumerator = enumerable.GetEnumerator();
+		if (!enumerator.MoveNext())
+			yield break;
+		var initialItem = enumerator.Current;
+		int previousIndex = indexSelector(initialItem);
+		int currentRangeStart = previousIndex;
+		var itemsBuilder = ImmutableArray.CreateBuilder<T>();
+		itemsBuilder.Add(initialItem);
+		while (enumerator.MoveNext())
+		{
+			var item = enumerator.Current;
+			var index = indexSelector(item);
+			if (index != previousIndex + 1)
+			{
+				yield return (itemsBuilder.DrainToImmutable(), currentRangeStart, previousIndex);
+				currentRangeStart = index;
+			}
+			itemsBuilder.Add(item);
+			previousIndex = index;
+		}
+
+		if (itemsBuilder.Count != 0)
+			yield return (itemsBuilder.ToImmutable(), currentRangeStart, previousIndex);
+	}
 }
\ No newline at end of file
diff --git a/SightKeeper.Domain/Model/DataSets/Screenshots/ScreenshotsLibrary.cs b/SightKeeper.Domain/Model/DataSets/Screenshots/ScreenshotsLibrary.cs
index 961903ae..a7d3e435 100644
--- a/SightKeeper.Domain/Model/DataSets/Screenshots/ScreenshotsLibrary.cs
+++ b/SightKeeper.Domain/Model/DataSets/Screenshots/ScreenshotsLibrary.cs
@@ -41,7 +41,8 @@ public ScreenshotsLibrary(DataSet dataSet)
     public override Screenshot<TAsset> CreateScreenshot(DateTime creationDate, out ImmutableArray<Screenshot> removedScreenshots)
     {
 	    Screenshot<TAsset> screenshot = new(this, creationDate);
-	    Guard.IsTrue(_screenshots.Add(screenshot));
+	    Guard.IsGreaterThan(creationDate, _screenshots[^1].CreationDate);
+	    _screenshots.Add(screenshot);
 	    removedScreenshots = ClearExceed();
 	    return screenshot;
     }
@@ -60,14 +61,22 @@ private ImmutableArray<Screenshot> ClearExceed()
 	    if (exceedAmount <= 0)
 		    return ImmutableArray<Screenshot>.Empty;
 	    var builder = ImmutableArray.CreateBuilder<Screenshot>(exceedAmount);
-	    var screenshotsToDelete = _screenshots.Where(screenshot => screenshot.Asset == null).Take(exceedAmount);
-	    foreach (var screenshot in screenshotsToDelete)
+	    var screenshotsToDelete =
+		    _screenshots
+			    .Select((screenshot, index) => (screenshot, index))
+			    .Where(tuple => tuple.screenshot.Asset == null)
+			    .Take(exceedAmount)
+			    .ToRanges(tuple => tuple.index)
+			    .OrderByDescending(tuple => tuple.start);
+	    foreach (var (tuples, start, end) in screenshotsToDelete)
 	    {
-		    Guard.IsTrue(_screenshots.Remove(screenshot));
-		    builder.Add(screenshot);
+		    _screenshots.RemoveRange(start, end);
+		    builder.Capacity += tuples.Length;
+		    foreach (var (screenshot, _) in tuples)
+			    builder.Add(screenshot);
 	    }
 	    return builder.ToImmutable();
     }
 
-    private readonly SortedSet<Screenshot<TAsset>> _screenshots = new(ScreenshotsDateComparer.Instance);
+    private readonly List<Screenshot<TAsset>> _screenshots = new();
 }
\ No newline at end of file