feat: implement correct getAttachments for board

2 files changed, 73 insertions, 17 deletions

diff --git a/src/Board/Board.test.ts b/src/Board/Board.test.ts
index 5023f0b..4bd6182 100644
--- a/src/Board/Board.test.ts
+++ b/src/Board/Board.test.ts
@@ -17,20 +17,20 @@ describe('Board', () => {
   });
 
   describe('getAttachments', () => {
-    it('Should correctly determine legal moves for 1-tile board', () => {
+    it('Should correctly determine legal attachments for 1-tile board', () => {
       const board = new Board();
       const attachTo = board.tiles[0];
       const tile = new Tile(Town, [Grass, Town, Grass, Town]);
-      const legalMoves = board.getAttachments(tile);
+      const attachments = board.getAttachments(tile);
 
-      assert.strictEqual(legalMoves.length, 4);
-      assert.deepStrictEqual(legalMoves[0], { side: 0, orientation: 1, attachTo, tile });
-      assert.deepStrictEqual(legalMoves[1], { side: 0, orientation: 3, attachTo, tile });
-      assert.deepStrictEqual(legalMoves[2], { side: 2, orientation: 0, attachTo, tile });
-      assert.deepStrictEqual(legalMoves[3], { side: 2, orientation: 2, attachTo, tile });
+      assert.strictEqual(attachments.length, 4);
+      assert.deepStrictEqual(attachments[0], { side: 0, orientation: 1, attachTo, tile });
+      assert.deepStrictEqual(attachments[1], { side: 0, orientation: 3, attachTo, tile });
+      assert.deepStrictEqual(attachments[2], { side: 2, orientation: 0, attachTo, tile });
+      assert.deepStrictEqual(attachments[3], { side: 2, orientation: 2, attachTo, tile });
     });
 
-    it.skip('Have a look at my nice attachments manually bro', () => {
+    it('Should correctly return legal attachments for complex board', () => {
       const board = new Board();
 
       board.attach({
@@ -50,7 +50,19 @@ describe('Board', () => {
       const tile = new Tile(Grass, [Town, Grass, Grass, Grass]);
 
       const attachments = board.getAttachments(tile);
-      attachments.forEach(attachment => board.previewAttachment(attachment));
+
+      // attachments.forEach(attachment => board.previewAttachment(attachment));
+
+      assert.strictEqual(attachments.length, 9);
+      assert.deepStrictEqual(attachments[0], { side: 2, orientation: 1, tile, attachTo: board.tiles[0] });
+      assert.deepStrictEqual(attachments[1], { side: 2, orientation: 2, tile, attachTo: board.tiles[0] });
+      assert.deepStrictEqual(attachments[2], { side: 2, orientation: 3, tile, attachTo: board.tiles[0] });
+      assert.deepStrictEqual(attachments[3], { side: 0, orientation: 2, tile, attachTo: board.tiles[1] });
+      assert.deepStrictEqual(attachments[4], { side: 3, orientation: 0, tile, attachTo: board.tiles[1] });
+      assert.deepStrictEqual(attachments[5], { side: 3, orientation: 2, tile, attachTo: board.tiles[1] });
+      assert.deepStrictEqual(attachments[6], { side: 3, orientation: 3, tile, attachTo: board.tiles[1] });
+      assert.deepStrictEqual(attachments[7], { side: 1, orientation: 3, tile, attachTo: board.tiles[2] });
+      assert.deepStrictEqual(attachments[8], { side: 2, orientation: 0, tile, attachTo: board.tiles[2] });
     });
   });
 
diff --git a/src/Board/Board.ts b/src/Board/Board.ts
index ef4b4a5..b114ff1 100644
--- a/src/Board/Board.ts
+++ b/src/Board/Board.ts
@@ -57,7 +57,58 @@ export default class Board {
   }
 
   getAttachments(tile: Tile): Attachment[] {
-    return _.flatten(this.tiles.map(attachTo => attachTo.getAttachments(tile)));
+    return _
+      .flatten(this.tiles.map(attachTo => attachTo.getAttachments(tile)))
+      .filter((attachment: Attachment) => this.isLegalAttachment(attachment));
+  }
+
+  previewAttachment(attachment: Attachment) {
+    console.log(attachment);
+    const previewBoard = _.cloneDeep(this);
+    previewBoard.attach(attachment);
+    previewBoard.print();
+  }
+
+  isLegalAttachment(attachment: Attachment) {
+    const { tile, side, attachTo, orientation } = attachment;
+
+    const xIncrement = {
+      [East]: 1,
+      [West]: -1,
+    };
+
+    const yIncrement = {
+      [North]: 1,
+      [South]: -1,
+    };
+
+    const position = {
+      x: attachTo.position.x + (xIncrement[side] || 0),
+      y: attachTo.position.y + (yIncrement[side] || 0),
+    };
+
+    const isBusy = _.find(this.tiles, { position });
+    if (isBusy) return false;
+
+    // TODO: compute this array at runtime
+    const neighborIncrements = [
+      { x: 0, y: -1, side: 0 },
+      { x: -1, y: 0, side: 1 },
+      { x: 0, y: 1, side: 2 },
+      { x: 1, y: 0, side: 3 },
+    ];
+
+    return _.every(_.map(neighborIncrements, ({ x, y, side }) => {
+      const neighbor = _.find(this.tiles, {
+        position: {
+          x: position.x + x,
+          y: position.y + y,
+        }
+      });
+      if (!neighbor) return true;
+      if (neighbor.getSide(side) !== tile.getSide(side - orientation + 2)) return false;
+      return true;
+    }));
   }
 
   attach(attachment: Attachment) {
@@ -86,11 +137,4 @@ export default class Board {
 
     this.tiles.push(tileOnBoard);
   }
-
-  previewAttachment(attachment: Attachment) {
-    console.log(attachment);
-    const previewBoard = _.cloneDeep(this);
-    previewBoard.attach(attachment);
-    previewBoard.print();
-  }
 }