refactor: extract ShapeBuilder from Helper

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Core/Geometry/ShapeBuilder.cs

@@ -0,0 +1,150 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+using OpenNest.Math;
+
+namespace OpenNest.Geometry
+{
+    public static class ShapeBuilder
+    {
+        public static List<Shape> GetShapes(IEnumerable<Entity> entities)
+        {
+            var lines = new List<Line>();
+            var arcs = new List<Arc>();
+            var circles = new List<Circle>();
+            var shapes = new List<Shape>();
+
+            var entities2 = new Queue<Entity>(entities);
+
+            while (entities2.Count > 0)
+            {
+                var entity = entities2.Dequeue();
+
+                switch (entity.Type)
+                {
+                    case EntityType.Arc:
+                        arcs.Add((Arc)entity);
+                        break;
+
+                    case EntityType.Circle:
+                        circles.Add((Circle)entity);
+                        break;
+
+                    case EntityType.Line:
+                        lines.Add((Line)entity);
+                        break;
+
+                    case EntityType.Shape:
+                        var shape = (Shape)entity;
+                        shape.Entities.ForEach(e => entities2.Enqueue(e));
+                        break;
+
+                    default:
+                        Debug.Fail("Unhandled geometry type");
+                        break;
+                }
+            }
+
+            foreach (var circle in circles)
+            {
+                var shape = new Shape();
+                shape.Entities.Add(circle);
+                shape.UpdateBounds();
+                shapes.Add(shape);
+            }
+
+            var entityList = new List<Entity>();
+
+            entityList.AddRange(lines);
+            entityList.AddRange(arcs);
+
+            while (entityList.Count > 0)
+            {
+                var next = entityList[0];
+                var shape = new Shape();
+                shape.Entities.Add(next);
+
+                entityList.RemoveAt(0);
+
+                Vector startPoint = new Vector();
+                Entity connected;
+
+                switch (next.Type)
+                {
+                    case EntityType.Arc:
+                        var arc = (Arc)next;
+                        startPoint = arc.EndPoint();
+                        break;
+
+                    case EntityType.Line:
+                        var line = (Line)next;
+                        startPoint = line.EndPoint;
+                        break;
+                }
+
+                while ((connected = GetConnected(startPoint, entityList)) != null)
+                {
+                    shape.Entities.Add(connected);
+                    entityList.Remove(connected);
+
+                    switch (connected.Type)
+                    {
+                        case EntityType.Arc:
+                            var arc = (Arc)connected;
+                            startPoint = arc.EndPoint();
+                            break;
+
+                        case EntityType.Line:
+                            var line = (Line)connected;
+                            startPoint = line.EndPoint;
+                            break;
+                    }
+                }
+
+                shape.UpdateBounds();
+                shapes.Add(shape);
+            }
+
+            return shapes;
+        }
+
+        internal static Entity GetConnected(Vector pt, IEnumerable<Entity> geometry)
+        {
+            var tol = Tolerance.ChainTolerance;
+
+            foreach (var geo in geometry)
+            {
+                switch (geo.Type)
+                {
+                    case EntityType.Arc:
+                        var arc = (Arc)geo;
+
+                        if (arc.StartPoint().DistanceTo(pt) <= tol)
+                            return arc;
+
+                        if (arc.EndPoint().DistanceTo(pt) <= tol)
+                        {
+                            arc.Reverse();
+                            return arc;
+                        }
+
+                        break;
+
+                    case EntityType.Line:
+                        var line = (Line)geo;
+
+                        if (line.StartPoint.DistanceTo(pt) <= tol)
+                            return line;
+
+                        if (line.EndPoint.DistanceTo(pt) <= tol)
+                        {
+                            line.Reverse();
+                            return line;
+                        }
+                        break;
+                }
+            }
+
+            return null;
+        }
+    }
+}

OpenNest.Core/Geometry/ShapeProfile.cs

@@ -16,7 +16,7 @@ namespace OpenNest.Geometry
 
         private void Update(List<Entity> entities)
         {
-            var shapes = Helper.GetShapes(entities);
+            var shapes = ShapeBuilder.GetShapes(entities);
 
             Perimeter = shapes[0];
             Cutouts = new List<Shape>();