Add WBS sorter

src/WbsSortHelper.cs

@@ -0,0 +1,89 @@
+using System;
+using System.Collections.Generic;
+using ProjectManager.SDK.Models;
+
+namespace ProjectManager.SDK 
+{
+    /// <summary>
+    /// Use this class to sort TaskDto objects according to their Work Breakdown Structure
+    /// </summary>
+    public class WbsSortHelper : IComparer<TaskDto>
+    {
+        int IComparer<TaskDto>.Compare(TaskDto t1, TaskDto t2)
+        {
+            // Sanity checks for null
+            if (t1 == null || t2 == null)
+            {
+                if (t1 == null && t2 != null)
+                {
+                    return 1;
+                }
+
+                if (t1 != null && t2 == null)
+                {
+                    return -1;
+                }
+
+                return 0;
+            }
+
+            try
+            {
+                var t1OutlineNumberArray = t1.Wbs.Trim().Split('.');
+                var t2OutlineNumberArray = t2.Wbs.Trim().Split('.');
+
+                for (int i = 0; i < t1OutlineNumberArray.Length; i++)
+                {
+                    if (i >= t2OutlineNumberArray.Length)
+                    {
+                        return 1; // In this situation = 2.1 > 2 return 1
+                    }
+                    if (int.TryParse(t1OutlineNumberArray[i], out int t1Number) && int.TryParse(t2OutlineNumberArray[i], out int t2Number))
+                    {
+                        if (t1Number == t2Number)
+                        {
+                            continue; // Continue the compare on the next item, e.g 1.1 and 1.2.3 are the same in the first comparison.
+                        }
+                        if (t1Number > t2Number)
+                        {
+                            return 1; // Return 1 if t1 > t2 on the same position like '3'.1 > '1'.1
+                        }
+                        if (t1Number < t2Number)
+                        {
+                            return -1;
+                        }
+                    }
+                    else
+                    {
+                        return -1;
+                    }
+                }
+
+                // t1 length > t2 length e.g. 1.1.5 > 1.1, retrun 1. note it passes the compare above so the position can compare will be the same.
+                if (t1OutlineNumberArray.Length > t2OutlineNumberArray.Length)
+                {
+                    return 1;
+                }
+                // e.g. 2.2 < 2.2.15, return -1;
+                if (t1OutlineNumberArray.Length < t2OutlineNumberArray.Length)
+                {
+                    return -1;
+                }
+
+                // If we cannot get answer from above, use index.
+                if (t1.Id.HasValue && t2.Id.HasValue)
+                {
+                    return t1.Id.Value.CompareTo(t2.Id.Value);
+                }
+            }
+            catch
+            {
+                if (t1.Id.HasValue && t2.Id.HasValue)
+                {
+                    return t1.Id.Value.CompareTo(t2.Id.Value);
+                }
+            }
+            return 0;
+        }
+    }
+}