Memorize dead pieces

chess/src/main/scala/Game.scala

@@ -3,17 +3,25 @@ package lila.chess
 import format.PgnDump
 
 case class Game(
-    board: Board,
-    player: Color,
+    board: Board = Board(),
+    player: Color = White,
     pgnMoves: String = "",
-    clock: Option[Clock] = None) {
+    clock: Option[Clock] = None,
+    deads: Map[Pos, Piece] = Map.empty) {
 
-  def playMove(from: Pos, to: Pos, promotion: PromotableRole = Queen): Valid[Game] = for {
-    move ← situation.move(from, to, promotion)
+  def playMove(
+    orig: Pos,
+    dest: Pos,
+    promotion: PromotableRole = Queen): Valid[Game] = for {
+    move ← situation.move(orig, dest, promotion)
   } yield {
     val newGame = copy(
       board = move.afterWithPositionHashesUpdated,
-      player = !player
+      player = !player,
+      deads = (for {
+        cpos ← move.capture
+        cpiece ← board(cpos)
+      } yield deads + ((cpos, cpiece))) getOrElse deads
     )
     val pgnMove = PgnDump.move(situation, move, newGame.situation)
     newGame.copy(pgnMoves = (pgnMoves + " " + pgnMove).trim)
@@ -23,10 +31,3 @@ case class Game(
 
   def pgnMovesList = pgnMoves.split(' ').toList
 }
-
-object Game {
-
-  def apply(): Game = Game(
-    board = Board(),
-    player = White)
-}

chess/src/test/scala/GameTest.scala

@@ -0,0 +1,19 @@
+package lila.chess
+
+import Pos._
+import format.Visual.addNewLines
+
+class GameTest extends ChessTest {
+
+  "capture a piece" should {
+    "add it to the dead pieces" in {
+      val game = Game().playMoves(
+        E2 -> E4,
+        D7 -> D5,
+        E4 -> D5)
+      game must beSuccess.like {
+        case g ⇒ g.deads must_== Map(D5 -> Black.pawn)
+      }
+    }
+  }
+}