1 files changed, 14 insertions, 19 deletions

diff --git a/src/Board/Board.ts b/src/Board/Board.ts
index 5f38088..b9a2136 100644
--- a/src/Board/Board.ts
+++ b/src/Board/Board.ts
@@ -88,8 +88,8 @@ export default class Board {
     }));
   }
 
-  isLegalAttachment(attachment: Attachment) {
-    const { tile, side, attachTo, orientation } = attachment;
+  calculateNewTilePosition(attachment: Attachment): TileOnBoard['position'] {
+    const { attachTo: { position }, side } = attachment
 
     const xIncrement = {
       [East]: 1,
@@ -101,10 +101,16 @@ export default class Board {
       [South]: -1,
     };
 
-    const position = {
-      x: attachTo.position.x + (xIncrement[side] || 0),
-      y: attachTo.position.y + (yIncrement[side] || 0),
+    return {
+      x: position.x + (xIncrement[side] || 0),
+      y: position.y + (yIncrement[side] || 0),
     };
+  }
+
+  isLegalAttachment(attachment: Attachment) {
+    const { tile, side, orientation } = attachment;
+
+    const position = this.calculateNewTilePosition(attachment);
 
     const isBusy = _.find(this.tiles, { position });
     if (isBusy) return false;
@@ -119,26 +125,15 @@ export default class Board {
   }
 
   attach(attachment: Attachment) {
-    const { tile, attachTo, side, orientation } = attachment;
-
-    const xIncrement = {
-      [East]: 1,
-      [West]: -1,
-    };
+    const { tile, orientation } = attachment;
 
-    const yIncrement = {
-      [North]: 1,
-      [South]: -1,
-    };
+    const position = this.calculateNewTilePosition(attachment);
 
     const tileOnBoard = new TileOnBoard(
       tile.center,
       tile.sides,
       tile.shield,
-      {
-        x: attachTo.position.x + (xIncrement[side] || 0),
-        y: attachTo.position.y + (yIncrement[side] || 0),
-      },
+      position,
       orientation,
     );