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

src/Go/Types.ts

@@ -37,7 +37,7 @@ export type BoardState = {
   board: Board;
   previousPlayer: GoColor | null;
   /** The previous board positions as a SimpleBoard */
-  previousBoards: SimpleBoard[];
+  previousBoards: string[];
   ai: GoOpponent;
   passCount: number;
   cheatCount: number;

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;

src/Go/boardState/boardState.ts

@@ -9,7 +9,7 @@ import {
   findLibertiesForChain,
   getAllChains,
   boardFromSimpleBoard,
-  simpleBoardFromBoard,
+  boardStringFromBoard,
 } from "../boardAnalysis/boardAnalysis";
 import { endGoGame } from "../boardAnalysis/scoring";
 import { addObstacles, resetCoordinates, rotate90Degrees } from "./offlineNodes";
@@ -89,15 +89,12 @@ export function makeMove(boardState: BoardState, x: number, y: number, player: G
     return false;
   }
 
-  // Only maintain last 7 moves
-  boardState.previousBoards.unshift(simpleBoardFromBoard(boardState.board));
-  if (boardState.previousBoards.length > 7) {
-    boardState.previousBoards.pop();
-  }
-
   const point = boardState.board[x][y];
   if (!point) return false;
 
+  // Add move to board history
+  boardState.previousBoards.unshift(boardStringFromBoard(boardState.board));
+
   point.color = player;
   boardState.previousPlayer = player;
   boardState.passCount = 0;

src/Go/ui/GoGameboardWrapper.tsx

@@ -9,7 +9,7 @@ import { SnackbarEvents } from "../../ui/React/Snackbar";
 import { getNewBoardState, getStateCopy, makeMove, passTurn, updateCaptures } from "../boardState/boardState";
 import { bitverseArt, weiArt } from "../boardState/asciiArt";
 import { getScore, resetWinstreak } from "../boardAnalysis/scoring";
-import { boardFromSimpleBoard, evaluateIfMoveIsValid, getAllValidMoves } from "../boardAnalysis/boardAnalysis";
+import { boardFromBoardString, evaluateIfMoveIsValid, getAllValidMoves } from "../boardAnalysis/boardAnalysis";
 import { useRerender } from "../../ui/React/hooks";
 import { OptionSwitch } from "../../ui/React/OptionSwitch";
 import { boardStyles } from "../boardState/goStyles";
@@ -150,7 +150,7 @@ export function GoGameboardWrapper({ showInstructions }: GoGameboardWrapperProps
     if (!boardState.previousBoards.length) return boardState;
     const priorState = getStateCopy(boardState);
     priorState.previousPlayer = boardState.previousPlayer === GoColor.black ? GoColor.white : GoColor.black;
-    priorState.board = boardFromSimpleBoard(boardState.previousBoards[0]);
+    priorState.board = boardFromBoardString(boardState.previousBoards[0]);
     updateCaptures(priorState.board, priorState.previousPlayer);
     return priorState;
   }

src/Go/ui/GoPoint.tsx

@@ -7,7 +7,7 @@ import { GoColor } from "@enums";
 import { columnIndexes } from "../Constants";
 import { findNeighbors } from "../boardState/boardState";
 import { pointStyle } from "../boardState/goStyles";
-import { findAdjacentLibertiesAndAlliesForPoint, getColorOnSimpleBoard } from "../boardAnalysis/boardAnalysis";
+import { findAdjacentLibertiesAndAlliesForPoint, getColorOnBoardString } from "../boardAnalysis/boardAnalysis";
 
 interface GoPointProps {
   state: BoardState;
@@ -42,7 +42,7 @@ export function GoPoint({ state, x, y, traditional, hover, valid, emptyPointOwne
   const sizeClass = getSizeClass(state.board[0].length, classes);
 
   const isNewStone =
-    state.previousBoards.length && getColorOnSimpleBoard(state.previousBoards[0], x, y) === GoColor.empty;
+    state.previousBoards.length && getColorOnBoardString(state.previousBoards[0], x, y) === GoColor.empty;
   const isPriorMove = player === state.previousPlayer && isNewStone;
 
   const emptyPointColorClass =

test/jest/Go/NetscriptGo.test.ts

@@ -92,9 +92,9 @@ describe("Netscript Go API unit tests", () => {
 
   describe("getGameState() tests", () => {
     it("should correctly retrieve the current game state", async () => {
-      const board = ["OXX..", ".....", ".....", "...XX", "...X."];
+      const board = ["OXX..", ".....", "..#..", "...XX", "...X."];
       const boardState = boardStateFromSimpleBoard(board, GoOpponent.Daedalus, GoColor.black);
-      boardState.previousBoards = [["OX..", ".....", ".....", "...XX", "...X."]];
+      boardState.previousBoards = ["OX.........#.....XX...X."];
       Go.currentGame = boardState;
 
       const result = getGameState();

test/jest/Go/boardAnalysis.test.ts

@@ -57,10 +57,10 @@ describe("Go board analysis tests", () => {
   it("identifies invalid moves from repeat", async () => {
     const board = [".X...", ".....", ".....", ".....", "....."];
     const boardState = boardStateFromSimpleBoard(board);
-    boardState.previousBoards.push([".X...", ".....", ".....", ".....", "....."]);
-    boardState.previousBoards.push([".X...", ".....", ".....", ".....", "....."]);
-    boardState.previousBoards.push([".X...", ".....", ".....", ".....", "....."]);
-    boardState.previousBoards.push(["OX...", ".....", ".....", ".....", "....."]);
+    boardState.previousBoards.push(".X.......................");
+    boardState.previousBoards.push(".X.......................");
+    boardState.previousBoards.push(".X.......................");
+    boardState.previousBoards.push("OX.......................");
     const validity = evaluateIfMoveIsValid(boardState, 0, 0, GoColor.white, false);
 
     expect(validity).toEqual(GoValidity.boardRepeated);