Better communication

Gameboard.ShogiUI.Sockets/Models/Coords.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Text.RegularExpressions;
+
+namespace Gameboard.ShogiUI.Sockets.Models
+{
+  public class Coords
+  {
+    private const string BoardNotationRegex = @"(?<file>[A-I])(?<rank>[1-9])";
+    private const char A = 'A';
+    public int X { get; }
+    public int Y { get; }
+    public Coords(int x, int y)
+    {
+      X = x;
+      Y = y;
+    }
+
+    public string ToBoardNotation()
+    {
+      var file = (char)(X + A);
+      var rank = Y + 1;
+      return $"{file}{rank}";
+    }
+
+    public static Coords FromBoardNotation(string notation)
+    {
+      if (string.IsNullOrEmpty(notation))
+      {
+        if (Regex.IsMatch(notation, BoardNotationRegex))
+        {
+          var match = Regex.Match(notation, BoardNotationRegex);
+          char file = match.Groups["file"].Value[0];
+          int rank = int.Parse(match.Groups["rank"].Value);
+          return new Coords(file - A, rank);
+        }
+        throw new ArgumentException("Board notation not recognized."); // TODO: Move this error handling to the service layer.
+      }
+      return new Coords(-1, -1); // Temporarily this is how I tell Gameboard.API that a piece came from the hand.
+    }
+  }
+}