implemented methods for Game

shared/src/main/scala/com/mogproject/mogami/core/game/Branch.scala

@@ -153,6 +153,16 @@ case class Branch(initialHash: StateHash,
   }
 
   def hasComment(pos: Int): Boolean = comments.contains(pos)
+
+  /**
+    * Create a truncated branch
+    *
+    * @param pos the point to truncate
+    */
+  def truncated(pos: Int): Branch = {
+    val relPos = pos - offset
+    copy(moves = moves.take(relPos), finalAction = None, comments = comments.filterKeys(_ <= pos), hint = Some(BranchHint(history.take(relPos + 1))))
+  }
 }
 
 object Branch extends SfenBranchReader with KifBranchReader {

shared/src/main/scala/com/mogproject/mogami/core/game/Game.scala

@@ -20,7 +20,7 @@ case class Game(trunk: Branch = Branch(),
     if (branchNo == 0) Some(trunk) else branches.isDefinedAt(branchNo - 1).option(branches(branchNo - 1))
 
   def withBranch[A](branchNo: BranchNo)(f: Branch => A): Option[A] = getBranch(branchNo).map(f)
-  
+
   def createBranch(position: GamePosition, move: Move): Option[(Game, BranchNo)] = ???
 
   def deleteBranch(branchNo: BranchNo): Option[Game] = ???
@@ -77,13 +77,30 @@ case class Game(trunk: Branch = Branch(),
   } else {
     getBranch(branchNo).flatMap(_.finalAction)
   }
+
+  /**
+    * Create a truncated game at a specific position
+    */
+  def truncated(gamePosition: GamePosition): Game = {
+    if (gamePosition.isTrunk) {
+      // delete branches if needed
+      copy(trunk = trunk.truncated(gamePosition.position), branches = branches.filter(_.offset <= gamePosition.position))
+    } else {
+      withBranch(gamePosition.branch) { br =>
+        copy(branches = branches.updated(gamePosition.branch, br.truncated(gamePosition.position)))
+      }.getOrElse(this)
+    }
+  }
 }
 
 object Game extends CsaGameReader with SfenGameReader with KifGameReader {
 
   type BranchNo = Int // branch number: root = 0
 
   case class GamePosition(branch: BranchNo, position: Int) {
+    require(branch >= 0, "branch must not be negative")
+    require(position >= 0, "position must not be negative")
+
     def isTrunk: Boolean = branch == 0
   }
 

shared/src/main/scala/com/mogproject/mogami/package.scala

@@ -81,6 +81,12 @@ package object mogami {
   type Game = com.mogproject.mogami.core.game.Game
   val Game = com.mogproject.mogami.core.game.Game
 
+  type Branch = com.mogproject.mogami.core.game.Branch
+  val Branch = com.mogproject.mogami.core.game.Branch
+
+  type GamePosition = com.mogproject.mogami.core.game.Game.GamePosition
+  val GamePosition = com.mogproject.mogami.core.game.Game.GamePosition
+
   type GameStatus = com.mogproject.mogami.core.game.GameStatus.GameStatus
   val GameStatus = com.mogproject.mogami.core.game.GameStatus
 

shared/src/test/scala/com/mogproject/mogami/core/game/GameSpec.scala

@@ -771,4 +771,46 @@ class GameSpec extends FlatSpec with MustMatchers with GeneratorDrivenPropertyCh
     g1.getFinalAction(2) mustBe Some(Resign())
     g1.getFinalAction(3) mustBe Some(IllegalMove(Move(BLACK, Some(Square(76)), Square(4), KING, false, false, None, None, false, None, false)))
   }
+
+  "Game#truncated" must "return truncated games" in {
+    Game().truncated(GamePosition(0, 0)) mustBe Game()
+    Game().truncated(GamePosition(0, 1)) mustBe Game()
+    Game().truncated(GamePosition(1, 0)) mustBe Game()
+
+
+    val s1 = SfenExtendedGame(
+      SfenExtendedBranch(
+        "lnsgkgsnl/1r5b1/ppppppppp/9/9/9/PPPPPPPPP/1B5R1/LNSGKGSNL b - 0 2g2f 5a4b 2f2e",
+        None,
+        Map(1 -> "mv1", 2 -> "mv2", 3 -> "mv3")
+      ),
+      Vector(
+        SfenExtendedBranch(
+          "2 7g7f 4b3b",
+          None,
+          Map(2 -> "m2")
+        ),
+        SfenExtendedBranch(
+          "2 5g5f 4b3b",
+          Some("r"),
+          Map(2 -> "v2", 4 -> "v4")
+        ),
+        SfenExtendedBranch(
+          "0",
+          Some("i 5i5a"),
+          Map.empty
+        )
+      )
+    )
+    val g1 = Game.parseSfenExtendedGame(s1)
+
+    g1.truncated(GamePosition(0, 3)) mustBe g1
+    g1.truncated(GamePosition(0, 2)).trunk.moves.length mustBe 2
+    g1.truncated(GamePosition(0, 2)).trunk.comments mustBe Map(1 -> "mv1", 2 -> "mv2")
+    g1.truncated(GamePosition(2, 3)).branches(2).comments mustBe Map(2 -> "v2")
+    g1.truncated(GamePosition(2, 4)).branches(2).status mustBe GameStatus.Playing
+    g1.truncated(GamePosition(0, 2)).branches.length mustBe 3
+    g1.truncated(GamePosition(0, 1)).branches.length mustBe 1
+    g1.truncated(GamePosition(0, 0)).branches.length mustBe 1
+  }
 }