From 9a53bc3e576d28382e4530925297f66cecf2129f Mon Sep 17 00:00:00 2001
From: Flaminel <flm.marius@gmail.com>
Date: Fri, 23 Oct 2026 02:11:49 +0300
Subject: [PATCH] removed duplicated weighted sampling loop from selectors

---
 .../Selectors/BalancedWeightedSelector.cs     | 29 +------------------
 .../CustomFormatGapWeightedSelector.cs        | 29 +------------------
 .../Selectors/OldestSearchWeightedSelector.cs | 11 ++++++-
 3 files changed, 12 insertions(+), 57 deletions(-)

diff --git a/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/BalancedWeightedSelector.cs b/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/BalancedWeightedSelector.cs
index 466fff06..a59263cb 100644
--- a/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/BalancedWeightedSelector.cs
+++ b/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/BalancedWeightedSelector.cs
@@ -30,37 +30,10 @@ public sealed class BalancedWeightedSelector : IItemSelector
             .ToDictionary(x => x.Id, x => x.Rank);
 
         // Composite weight = average of both ranks (higher = more likely to be selected)
-        var selected = new List<long>(count);
         var pool = candidates
             .Select(c => (c.Id, Weight: (searchRanks[c.Id] + ageRanks[c.Id]) / 2.0))
             .ToList();
 
-        for (int i = 0; i < count && pool.Count > 0; i++)
-        {
-            double totalWeight = 0;
-            for (int j = 0; j < pool.Count; j++)
-            {
-                totalWeight += pool[j].Weight;
-            }
-
-            double target = Random.Shared.NextDouble() * totalWeight;
-            double cumulative = 0;
-            int selectedIndex = pool.Count - 1;
-
-            for (int j = 0; j < pool.Count; j++)
-            {
-                cumulative += pool[j].Weight;
-                if (cumulative >= target)
-                {
-                    selectedIndex = j;
-                    break;
-                }
-            }
-
-            selected.Add(pool[selectedIndex].Id);
-            pool.RemoveAt(selectedIndex);
-        }
-
-        return selected;
+        return OldestSearchWeightedSelector.WeightedRandom(pool, count);
     }
 }
diff --git a/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/CustomFormatGapWeightedSelector.cs b/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/CustomFormatGapWeightedSelector.cs
index 8f85fa39..acafdde2 100644
--- a/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/CustomFormatGapWeightedSelector.cs
+++ b/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/CustomFormatGapWeightedSelector.cs
@@ -25,37 +25,10 @@ public sealed class CustomFormatGapWeightedSelector : IItemSelector
         double maxGap = candidates.Max(c => c.Gap);
 
         // The recency half is at least 1/n, so every weight stays above zero
-        List<long> selected = new(count);
         List<(long Id, double Weight)> pool = candidates
             .Select(c => (c.Id, Weight: 0.5 * (maxGap > 0 ? c.Gap / maxGap : 0) + 0.5 * searchRanks[c.Id] / n))
             .ToList();
 
-        for (int i = 0; i < count && pool.Count > 0; i++)
-        {
-            double totalWeight = 0;
-            for (int j = 0; j < pool.Count; j++)
-            {
-                totalWeight += pool[j].Weight;
-            }
-
-            double target = Random.Shared.NextDouble() * totalWeight;
-            double cumulative = 0;
-            int selectedIndex = pool.Count - 1;
-
-            for (int j = 0; j < pool.Count; j++)
-            {
-                cumulative += pool[j].Weight;
-                if (cumulative >= target)
-                {
-                    selectedIndex = j;
-                    break;
-                }
-            }
-
-            selected.Add(pool[selectedIndex].Id);
-            pool.RemoveAt(selectedIndex);
-        }
-
-        return selected;
+        return OldestSearchWeightedSelector.WeightedRandom(pool, count);
     }
 }
diff --git a/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/OldestSearchWeightedSelector.cs b/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/OldestSearchWeightedSelector.cs
index f7a1934b..71f7782d 100644
--- a/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/OldestSearchWeightedSelector.cs
+++ b/code/backend/Cleanuparr.Infrastructure/Features/Seeker/Selectors/OldestSearchWeightedSelector.cs
@@ -33,7 +33,6 @@ public sealed class OldestSearchWeightedSelector : IItemSelector
         int count)
     {
         int n = ranked.Count;
-        var selected = new List<long>(count);
 
         // Build initial weights from rank: highest rank (index 0) gets weight N, lowest gets 1
         var pool = new List<(long Id, double Weight)>(n);
@@ -42,6 +41,16 @@ public sealed class OldestSearchWeightedSelector : IItemSelector
             pool.Add((ranked[i].Id, n - i));
         }
 
+        return WeightedRandom(pool, count);
+    }
+
+    /// <summary>
+    /// Performs weighted random selection without replacement. Consumes <paramref name="pool"/>.
+    /// </summary>
+    internal static List<long> WeightedRandom(List<(long Id, double Weight)> pool, int count)
+    {
+        List<long> selected = new(count);
+
         for (int i = 0; i < count && pool.Count > 0; i++)
         {
             double totalWeight = 0;