feat: add ContourInfo model with shape classification logic

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

OpenNest.Core/Converters/ContourInfo.cs

@@ -0,0 +1,132 @@
+using OpenNest.Geometry;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace OpenNest.Converters
+{
+    public enum ContourClassification
+    {
+        Perimeter,
+        Hole,
+        Etch,
+        Open
+    }
+
+    public sealed class ContourInfo
+    {
+        public Shape Shape { get; }
+        public ContourClassification Type { get; private set; }
+        public string Label { get; private set; }
+
+        private ContourInfo(Shape shape, ContourClassification type, string label)
+        {
+            Shape = shape;
+            Type = type;
+            Label = label;
+        }
+
+        public string DirectionLabel
+        {
+            get
+            {
+                if (Type == ContourClassification.Open || Type == ContourClassification.Etch)
+                    return "Open";
+                var poly = Shape.ToPolygon();
+                if (poly == null || poly.Vertices.Count < 3)
+                    return "?";
+                return poly.RotationDirection() == RotationType.CW ? "CW" : "CCW";
+            }
+        }
+
+        public string DimensionLabel
+        {
+            get
+            {
+                if (Shape.Entities.Count == 1 && Shape.Entities[0] is Circle c)
+                    return $"Circle R{c.Radius:0.#}";
+                Shape.UpdateBounds();
+                var box = Shape.BoundingBox;
+                return $"{box.Width:0.#} x {box.Length:0.#}";
+            }
+        }
+
+        public void Reverse()
+        {
+            Shape.Reverse();
+        }
+
+        public static List<ContourInfo> Classify(List<Shape> shapes)
+        {
+            if (shapes.Count == 0)
+                return new List<ContourInfo>();
+
+            // Ensure bounding boxes are up to date before comparing
+            foreach (var s in shapes)
+                s.UpdateBounds();
+
+            // Find perimeter — largest bounding box area
+            var perimeterIndex = 0;
+            var maxArea = shapes[0].BoundingBox.Area();
+            for (var i = 1; i < shapes.Count; i++)
+            {
+                var area = shapes[i].BoundingBox.Area();
+                if (area > maxArea)
+                {
+                    maxArea = area;
+                    perimeterIndex = i;
+                }
+            }
+
+            var result = new List<ContourInfo>();
+            var holeCount = 0;
+            var etchCount = 0;
+            var openCount = 0;
+
+            // Non-perimeter shapes first (matches CNC cut order: holes before perimeter)
+            for (var i = 0; i < shapes.Count; i++)
+            {
+                if (i == perimeterIndex) continue;
+                var shape = shapes[i];
+                var type = ClassifyShape(shape);
+
+                string label;
+                switch (type)
+                {
+                    case ContourClassification.Hole:
+                        holeCount++;
+                        label = $"Hole {holeCount}";
+                        break;
+                    case ContourClassification.Etch:
+                        etchCount++;
+                        label = etchCount == 1 ? "Etch" : $"Etch {etchCount}";
+                        break;
+                    default:
+                        openCount++;
+                        label = openCount == 1 ? "Open" : $"Open {openCount}";
+                        break;
+                }
+
+                result.Add(new ContourInfo(shape, type, label));
+            }
+
+            // Perimeter last
+            result.Add(new ContourInfo(shapes[perimeterIndex], ContourClassification.Perimeter, "Perimeter"));
+
+            return result;
+        }
+
+        private static ContourClassification ClassifyShape(Shape shape)
+        {
+            // Check etch layer — all entities must be on ETCH layer
+            if (shape.Entities.Count > 0 &&
+                shape.Entities.All(e => string.Equals(e.Layer?.Name, "ETCH", StringComparison.OrdinalIgnoreCase)))
+                return ContourClassification.Etch;
+
+            if (shape.IsClosed())
+                return ContourClassification.Hole;
+
+            return ContourClassification.Open;
+        }
+    }
+}