refactor(engine): extract PairFiller candidate selection and remnant filling

Splits PairCandidateSelector (strip-mode candidate ranking) and PairRemnantFiller (leftover L-shaped area fill) out of PairFiller into their own classes. Pure extraction — logic is unchanged, just relocated and given dedicated unit boundaries so each piece can be tested and reasoned about on its own.
2026-09-22 09:51:06 -04:00
parent 6f250b5730
commit 86f6c9efa1
3 changed files with 414 additions and 218 deletions
@@ -0,0 +1,123 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Threading;
+using OpenNest.Engine.Strategies;
+using OpenNest.Geometry;
+using OpenNest.Math;
+
+namespace OpenNest.Engine.Fill
+{
+    /// <summary>
+    /// Fills the leftover L-shaped area (top strip + right strip) around a pair grid
+    /// with the same drawing, caching results by drawing/box/spacing.
+    /// </summary>
+    public class PairRemnantFiller
+    {
+        private readonly double partSpacing;
+        private readonly IFillComparer comparer;
+
+        public PairRemnantFiller(double partSpacing, IFillComparer comparer)
+        {
+            this.partSpacing = partSpacing;
+            this.comparer = comparer;
+        }
+
+        public int EstimateUpperBound(
+            List<Part> gridParts,
+            Box workArea,
+            double maxUtilization,
+            double partArea
+        )
+        {
+            var gridBox = ((IEnumerable<IBoundable>)gridParts).GetBoundingBox();
+
+            // L-shaped remnant: top strip (full width) + right strip (grid height only)
+            var topHeight = System.Math.Max(0, workArea.Top - gridBox.Top);
+            var rightWidth = System.Math.Max(0, workArea.Right - gridBox.Right);
+
+            var topArea = workArea.Length * topHeight;
+            var rightArea = rightWidth * System.Math.Min(gridBox.Top - workArea.Y, workArea.Width);
+            var remnantArea = topArea + rightArea;
+
+            return (int)(remnantArea * maxUtilization / partArea) + 1;
+        }
+
+        public List<Part> Fill(
+            List<Part> gridParts,
+            Drawing drawing,
+            Box workArea,
+            CancellationToken token
+        )
+        {
+            var gridBox = ((IEnumerable<IBoundable>)gridParts).GetBoundingBox();
+            var partBox = drawing.Program.BoundingBox();
+            var minDim = System.Math.Min(partBox.Width, partBox.Length) + 2 * partSpacing;
+
+            List<Part> bestRemnant = null;
+
+            // Try top remnant (full width, above grid)
+            var topY = gridBox.Top + partSpacing;
+            var topLength = workArea.Top - topY;
+            if (topLength >= minDim)
+            {
+                var topBox = new Box(workArea.X, topY, workArea.Length, topLength);
+                var parts = FillRemnantBox(drawing, topBox, token);
+                if (parts != null && parts.Count > (bestRemnant?.Count ?? 0))
+                    bestRemnant = parts;
+            }
+
+            // Try right remnant (full height, right of grid)
+            var rightX = gridBox.Right + partSpacing;
+            var rightWidth = workArea.Right - rightX;
+            if (rightWidth >= minDim)
+            {
+                var rightBox = new Box(rightX, workArea.Y, rightWidth, workArea.Width);
+                var parts = FillRemnantBox(drawing, rightBox, token);
+                if (parts != null && parts.Count > (bestRemnant?.Count ?? 0))
+                    bestRemnant = parts;
+            }
+
+            return bestRemnant;
+        }
+
+        private List<Part> FillRemnantBox(Drawing drawing, Box remnantBox, CancellationToken token)
+        {
+            var cachedResult = FillResultCache.Get(drawing, remnantBox, partSpacing);
+            if (cachedResult != null)
+            {
+                Debug.WriteLine($"[PairFiller] Remnant CACHE HIT: {cachedResult.Count} parts");
+                return cachedResult;
+            }
+
+            var filler = new FillLinear(remnantBox, partSpacing) { Label = "Pairs-Remnant" };
+            List<Part> parts = null;
+
+            foreach (var angle in new[] { 0.0, Angle.HalfPI })
+            {
+                token.ThrowIfCancellationRequested();
+                var result = FillHelpers.FillWithDirectionPreference(
+                    dir => filler.Fill(drawing, angle, dir),
+                    null,
+                    comparer,
+                    remnantBox
+                );
+
+                if (result != null && result.Count > (parts?.Count ?? 0))
+                    parts = result;
+            }
+
+            Debug.WriteLine(
+                $"[PairFiller] Remnant: {parts?.Count ?? 0} parts in "
+                    + $"{remnantBox.Width:F2}x{remnantBox.Length:F2}"
+            );
+
+            if (parts != null && parts.Count > 0)
+            {
+                FillResultCache.Store(drawing, remnantBox, partSpacing, parts);
+                return parts;
+            }
+
+            return null;
+        }
+    }
+}