Multi-bin nesting

SawCut/Nesting/MultiBinEngine.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace SawCut.Nesting
+{
+    public class MultiBinEngine : IEngine
+    {
+        public List<MultiBin> Bins { get; set; }
+
+        public double Spacing { get; set; }
+
+        public Result Pack(List<BinItem> items)
+        {
+            var bins = Bins
+                .Where(b => b.Length > 0)
+                .OrderByDescending(b => b.Priority)
+                .ThenBy(b => b.Length)
+                .ToList();
+
+            var result = new Result();
+            var remainingItems = new List<BinItem>(items);
+
+            foreach (var bin in bins)
+            {
+                var e = new Engine2();
+                e.MaxBinCount = bin.Quantity;
+                e.StockLength = bin.Length;
+                e.Spacing = Spacing;
+                var r = e.Pack(remainingItems);
+
+                result.Bins.AddRange(r.Bins);
+                remainingItems = r.ItemsNotUsed;
+            }
+
+            result.ItemsNotUsed = remainingItems;
+
+            // sanity check
+
+            //var itemsNested = result.Bins.SelectMany(b => b.Items).ToList();
+            //var lengths = items.Select(i => i.Length).Distinct();
+
+            //foreach (var length in lengths)
+            //{
+            //    var nameLengthGroups1 = items.Where(i => i.Length == length).GroupBy(i => i.Name).ToList();
+            //    var nameLengthGroups2 = itemsNested.Where(i => i.Length == length).GroupBy(i => i.Name).ToList();
+
+            //    foreach (var group in nameLengthGroups1)
+            //    {
+            //        var name = group.Key;
+
+            //        var nestedWithSameName = nameLengthGroups2.FirstOrDefault(g => g.Key == group.Key);
+
+            //        if (group.Count() != nestedWithSameName.Count())
+            //        {
+            //            throw new Exception("Failed sanity check.");
+
+            //        }
+            //    }
+
+            //    if (nameLengthGroups1.Count() != nameLengthGroups2.Count())
+            //    {
+            //        throw new Exception("Failed sanity check.");
+            //    }
+            //}
+
+            return result;
+        }
+    }
+}