IPVGO: Record full history to avoid infinite ko capture loops on larger boards (#1299)

src/Go/boardAnalysis/boardAnalysis.ts

@@ -44,7 +44,7 @@ export function evaluateIfMoveIsValid(boardState: BoardState, x: number, y: numb
   }
 
   // Detect if the move might be an immediate repeat (only one board of history is saved to check)
-  const possibleRepeat = boardState.previousBoards.find((board) => getColorOnSimpleBoard(board, x, y) === player);
+  const possibleRepeat = boardState.previousBoards.find((board) => getColorOnBoardString(board, x, y) === player);
 
   if (shortcut) {
     // If the current point has some adjacent open spaces, it is not suicide. If the move is not repeated, it is legal
@@ -86,8 +86,8 @@ export function evaluateIfMoveIsValid(boardState: BoardState, x: number, y: numb
     return GoValidity.noSuicide;
   }
   if (possibleRepeat && boardState.previousBoards.length) {
-    const simpleEvalBoard = simpleBoardFromBoard(evaluationBoard);
-    if (boardState.previousBoards.find((board) => areSimpleBoardsIdentical(simpleEvalBoard, board))) {
+    const simpleEvalBoard = boardStringFromBoard(evaluationBoard);
+    if (boardState.previousBoards.includes(simpleEvalBoard)) {
       return GoValidity.boardRepeated;
     }
   }
@@ -548,7 +548,8 @@ export function findAdjacentLibertiesAndAlliesForPoint(
 }
 
 /**
- * Retrieves a simplified version of the board state. "X" represents black pieces, "O" white, and "." empty points.
+ * Retrieves a simplified version of the board state.
+ * "X" represents black pieces, "O" white, "." empty points, and "#" offline nodes.
  *
  * For example, a 5x5 board might look like this:
  * ```
@@ -563,14 +564,15 @@ export function findAdjacentLibertiesAndAlliesForPoint(
  *
  * Each string represents a vertical column on the board, and each character in the string represents a point.
  *
- * Traditional notation for Go is e.g. "B,1" referring to second ("B") column, first rank. This is the equivalent of index [1][0].
+ * Traditional notation for Go is e.g. "B,1" referring to second ("B") column, first rank. This is the equivalent of
+ * index (1 * N) + 0 , where N is the size of the board.
  *
- * Note that the [0][0] point is shown on the bottom-left on the visual board (as is traditional), and each
+ * Note that index 0 (the [0][0] point) is shown on the bottom-left on the visual board (as is traditional), and each
  * string represents a vertical column on the board. In other words, the printed example above can be understood to
  * be rotated 90 degrees clockwise compared to the board UI as shown in the IPvGO game.
  *
  */
-export function simpleBoardFromBoard(board: Board): string[] {
+export function simpleBoardFromBoard(board: Board): SimpleBoard {
   return board.map((column) =>
     column.reduce((str, point) => {
       if (!point) {
@@ -587,6 +589,39 @@ export function simpleBoardFromBoard(board: Board): string[] {
   );
 }
 
+/**
+ * Returns a string representation of the given board.
+ * The string representation is the same as simpleBoardFromBoard() but concatenated into a single string
+ *
+ * For example, a 5x5 board might look like this:
+ * ```
+ *   "XX.O.X..OO.XO..XXO...XOO."
+ * ```
+ */
+export function boardStringFromBoard(board: Board): string {
+  return simpleBoardFromBoard(board).join("");
+}
+
+/**
+ * Returns a full board object from a string representation of the board.
+ * The string representation is the same as simpleBoardFromBoard() but concatenated into a single string
+ *
+ * For example, a 5x5 board might look like this:
+ * ```
+ *   "XX.O.X..OO.XO..XXO...XOO."
+ * ```
+ */
+export function boardFromBoardString(boardString: string): Board {
+  // Turn the SimpleBoard string into a string array, allowing access of each point via indexes e.g. [0][1]
+  const boardSize = Math.round(Math.sqrt(boardString.length));
+  const boardTiles = boardString.split("");
+  const simpleBoardArray = Array(boardSize).map((_, index) =>
+    boardTiles.slice(index * boardSize, (index + 1) * boardSize).join(""),
+  );
+
+  return boardFromSimpleBoard(simpleBoardArray);
+}
+
 /** Creates a board object from a simple board. The resulting board has no analytics (liberties/chains) */
 export function boardFromSimpleBoard(simpleBoard: SimpleBoard): Board {
   return simpleBoard.map((column, x) =>
@@ -624,8 +659,9 @@ export function areSimpleBoardsIdentical(simpleBoard1: SimpleBoard, simpleBoard2
   return simpleBoard1.every((column, x) => column === simpleBoard2[x]);
 }
 
-export function getColorOnSimpleBoard(simpleBoard: SimpleBoard, x: number, y: number): GoColor | null {
-  const char = simpleBoard[x]?.[y];
+export function getColorOnBoardString(boardString: string, x: number, y: number): GoColor | null {
+  const boardSize = Math.round(Math.sqrt(boardString.length));
+  const char = boardString[x * boardSize + y];
   if (char === "X") return GoColor.black;
   if (char === "O") return GoColor.white;
   if (char === ".") return GoColor.empty;
@@ -643,7 +679,7 @@ export function getPreviousMove(): [number, number] | null {
     const row = Go.currentGame.board[+rowIndexString] ?? [];
     for (const pointIndexString in row) {
       const point = row[+pointIndexString];
-      const priorColor = point && priorBoard && getColorOnSimpleBoard(priorBoard, point.x, point.y);
+      const priorColor = point && priorBoard && getColorOnBoardString(priorBoard, point.x, point.y);
       const currentColor = point?.color;
       const isPreviousPlayer = currentColor === Go.currentGame.previousPlayer;
       const isChanged = priorColor !== currentColor;