Store MultiPointState in History to prevent doubling when there is no need

Author: Matt Tucker

src/main/scala/History.scala

@@ -20,6 +20,8 @@ case class Score(p1: Int = 0, p2: Int = 0) {
 
 }
 
+case class MultiPointState(target: Int, p1Points: Int = 0, p2Points: Int = 0)
+
 sealed abstract class History(
     val lastTurn: List[Uci] = List.empty,
     val currentTurn: List[Uci] = List.empty,
@@ -32,6 +34,7 @@ sealed abstract class History(
     val kingMoves: draughts.KingMoves = draughts.KingMoves(),
     val score: Score = Score(0, 0),
     val captures: Score = Score(0, 0),
+    val multiPointState: Option[MultiPointState] = None,
     val halfMoveClock: Int = 0
 ) {
 
@@ -119,7 +122,8 @@ object History {
         forcedTurn = h.forcedTurn,
         positionHashes = h.positionHashes,
         halfMoveClock = h.halfMoveClock,
-        score = h.score
+        score = h.score,
+        multiPointState = h.multiPointState
       )
 
   final case class Abalone(h: abalone.History)
@@ -154,6 +158,7 @@ object History {
       kingMoves: draughts.KingMoves = draughts.KingMoves(),
       score: Score = Score(0, 0),
       captures: Score = Score(0, 0),
+      multiPointState: Option[MultiPointState] = None,
       halfMoveClock: Int = 0
   ): History = lib match {
     case GameLogic.Draughts()     =>
@@ -228,7 +233,8 @@ object History {
           forcedTurn = forcedTurn,
           positionHashes = positionHashes,
           halfMoveClock = halfMoveClock,
-          score = score
+          score = score,
+          multiPointState = multiPointState
         )
       )
     case GameLogic.Abalone()      =>

src/main/scala/backgammon/CubeData.scala

@@ -1,6 +1,6 @@
 package strategygames.backgammon
 
-import strategygames.Player
+import strategygames.{ MultiPointState, Player }
 
 case class CubeData(
     value: Int,
@@ -9,11 +9,16 @@ case class CubeData(
     rejected: Boolean
 ) {
 
-  def canOffer(player: Player): Boolean =
-    !underOffer && value < 64 && owner != Some(!player)
+  def canOffer(player: Player, multiPointState: Option[MultiPointState]): Boolean =
+    !underOffer &&
+      owner != Some(!player) &&
+      value < CubeData.MAX_VALUE &&
+      value < multiPointState.fold(CubeData.MAX_VALUE)(mps =>
+        mps.target - player.fold(mps.p1Points, mps.p2Points)
+      )
 
   def offer(player: Player): CubeData =
-    if (value >= 64) sys.error("Cannot offer cube beyond 64")
+    if (value >= CubeData.MAX_VALUE) sys.error(s"Cannot offer cube beyond {CubeData.MAX_VALUE}")
     else if (value > 1 && Some(player) != owner) sys.error(s"Cube offer from invalid player: ${player}")
     else if (value == 1) copy(owner = Some(player), underOffer = true)
     else copy(underOffer = true)
@@ -31,5 +36,9 @@ case class CubeData(
 }
 
 object CubeData {
+
   val init = CubeData(1, None, false, false)
+
+  val MAX_VALUE = 64
+
 }

src/main/scala/backgammon/History.scala

@@ -1,6 +1,6 @@
 package strategygames.backgammon
 
-import strategygames.Score
+import strategygames.{ MultiPointState, Score }
 
 import format.Uci
 
@@ -11,6 +11,7 @@ case class History(
     justUsedUndo: Boolean = false,
     positionHashes: PositionHash = Array.empty,
     score: Score = Score(0, 0),
+    multiPointState: Option[MultiPointState] = None,
     // this is tracking fullMove for Backgammon
     halfMoveClock: Int = 0
 ) {

src/main/scala/backgammon/variant/Variant.scala

@@ -446,7 +446,7 @@ abstract class Variant private[variant] (
     else
       situation.board.cubeData match {
         case Some(cubeData) =>
-          if (cubeData.canOffer(situation.player))
+          if (cubeData.canOffer(situation.player, situation.board.history.multiPointState))
             List(
               CubeAction(
                 interaction = OfferDouble,