Add Koth (experimental)

[vchess.git] / client / src / variants / Sittuyin.js

import { ChessRules, Move, PiPo } from "@/base_rules";
import { randInt } from "@/utils/alea";

export class SittuyinRules extends ChessRules {
  static get HasFlags() {
    return false;
  }

  static get HasEnpassant() {
    return false;
  }

  static get PawnSpecs() {
    return Object.assign(
      {},
      ChessRules.PawnSpecs,
      {
        // Promotions are handled differently here
        promotions: [V.QUEEN]
      }
    );
  }

  static GenRandInitFen() {
    return "8/8/4pppp/pppp4/4PPPP/PPPP4/8/8 w 0";
  }

  re_setReserve(subTurn) {
    const mc = this.movesCount;
    const wc = (mc == 0 ? 1 : 0);
    const bc = (mc <= 1 ? 1 : 0);
    this.reserve = {
      w: {
        [V.ROOK]: wc * 2,
        [V.KNIGHT]: wc * 2,
        [V.BISHOP]: wc * 2,
        [V.QUEEN]: wc,
        [V.KING]: wc
      },
      b: {
        [V.ROOK]: bc * 2,
        [V.KNIGHT]: bc * 2,
        [V.BISHOP]: bc * 2,
        [V.QUEEN]: bc,
        [V.KING]: bc
      }
    }
    this.subTurn = subTurn || 1;
  }

  setOtherVariables(fen) {
    super.setOtherVariables(fen);
    if (this.movesCount <= 1) this.re_setReserve();
  }

  getPpath(b) {
    return "Sittuyin/" + b;
  }

  getColor(i, j) {
    if (i >= V.size.x) return i == V.size.x ? "w" : "b";
    return this.board[i][j].charAt(0);
  }

  getPiece(i, j) {
    if (i >= V.size.x) return V.RESERVE_PIECES[j];
    return this.board[i][j].charAt(1);
  }

  getReservePpath(index, color) {
    return "Sittuyin/" + color + V.RESERVE_PIECES[index];
  }

  static get RESERVE_PIECES() {
    return [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.KING];
  }

  getPotentialMovesFrom([x, y]) {
    if (this.movesCount >= 2) return super.getPotentialMovesFrom([x, y]);
    // Only reserve moves are allowed for now:
    if (V.OnBoard(x, y)) return [];
    const color = this.turn;
    const p = V.RESERVE_PIECES[y];
    if (this.reserve[color][p] == 0) return [];
    const iBound =
      p != V.ROOK
        ? (color == 'w' ? [4, 7] : [0, 3])
        : (color == 'w' ? [7, 7] : [0, 0]);
    const jBound = (i) => {
      if (color == 'w' && i == 4) return [4, 7];
      if (color == 'b' && i == 3) return [0, 3];
      return [0, 7];
    };
    let moves = [];
    for (let i = iBound[0]; i <= iBound[1]; i++) {
      const jb = jBound(i);
      for (let j = jb[0]; j <= jb[1]; j++) {
        if (this.board[i][j] == V.EMPTY) {
          let mv = new Move({
            appear: [
              new PiPo({
                x: i,
                y: j,
                c: color,
                p: p
              })
            ],
            vanish: [],
            start: { x: x, y: y },
            end: { x: i, y: j }
          });
          moves.push(mv);
        }
      }
    }
    return moves;
  }

  getPotentialPawnMoves([x, y]) {
    const color = this.turn;
    const shiftX = V.PawnSpecs.directions[color];
    let moves = [];
    if (x + shiftX >= 0 && x + shiftX < 8) {
      if (this.board[x + shiftX][y] == V.EMPTY)
        // One square forward
        moves.push(this.getBasicMove([x, y], [x + shiftX, y]));
      // Captures
      for (let shiftY of [-1, 1]) {
        if (
          y + shiftY >= 0 && y + shiftY < 8 &&
          this.board[x + shiftX][y + shiftY] != V.EMPTY &&
          this.canTake([x, y], [x + shiftX, y + shiftY])
        ) {
          moves.push(this.getBasicMove([x, y], [x + shiftX, y + shiftY]));
        }
      }
    }
    let queenOnBoard = false;
    let pawnsCount = 0;
    outerLoop: for (let i=0; i<8; i++) {
      for (let j=0; j<8; j++) {
        if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) {
          const p = this.getPiece(i, j);
          if (p == V.QUEEN) {
            queenOnBoard = true;
            break outerLoop;
          }
          else if (p == V.PAWN && pawnsCount <= 1) pawnsCount++;
        }
      }
    }
    if (
      !queenOnBoard &&
      (
        pawnsCount == 1 ||
        (color == 'w' && ((y <= 3 && x == y) || (y >= 4 && x == 7 - y))) ||
        (color == 'b' && ((y >= 4 && x == y) || (y <= 3 && x == 7 - y)))
      )
    ) {
      const addPromotion = ([xx, yy], moveTo) => {
        // The promoted pawn shouldn't attack anything,
        // and the promotion shouldn't discover a rook attack on anything.
        const finalSquare = (!moveTo ? [x, y] : [xx, yy]);
        let validP = true;
        for (let step of V.steps[V.BISHOP]) {
          const [i, j] = [finalSquare[0] + step[0], finalSquare[1] + step[1]];
          if (
            V.OnBoard(i, j) &&
            this.board[i][j] != V.EMPTY &&
            this.getColor(i, j) != color
          ) {
            validP = false;
            break;
          }
        }
        if (validP && !!moveTo) {
          // Also check rook discovered attacks on the enemy king
          let found = {
            "0,-1": 0,
            "0,1": 0,
            "1,0": 0,
            "-1,0": 0
          };
          // TODO: check opposite steps one after another, which could
          // save some time (no need to explore the other line).
          for (let step of V.steps[V.ROOK]) {
            let [i, j] = [x + step[0], y + step[1]];
            while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
              i += step[0];
              j += step[1];
            }
            if (V.OnBoard(i, j)) {
              const colIJ = this.getColor(i, j);
              const pieceIJ = this.getPiece(i, j);
              if (colIJ != color && pieceIJ == V.KING)
                found[step[0] + "," + step[1]] = -1;
              else if (colIJ == color && pieceIJ == V.ROOK)
                found[step[0] + "," + step[1]] = 1;
            }
          }
          if (
            (found["0,-1"] * found["0,1"] < 0) ||
            (found["-1,0"] * found["1,0"] < 0)
          ) {
            validP = false;
          }
        }
        if (validP) {
          moves.push(
            new Move({
              appear: [
                new PiPo({
                  x: !!moveTo ? xx : x,
                  y: yy, //yy == y if !!moveTo
                  c: color,
                  p: V.QUEEN
                })
              ],
              vanish: [
                new PiPo({
                  x: x,
                  y: y,
                  c: color,
                  p: V.PAWN
                })
              ],
              start: { x: x, y: y },
              end: { x: xx, y: yy }
            })
          );
        }
      };
      // In-place promotion always possible:
      addPromotion([x - shiftX, y]);
      for (let step of V.steps[V.BISHOP]) {
        const [i, j] = [x + step[0], y + step[1]];
        if (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY)
          addPromotion([i, j], "moveTo");
      }
    }
    return moves;
  }

  getPotentialBishopMoves(sq) {
    const forward = (this.turn == 'w' ? -1 : 1);
    return this.getSlideNJumpMoves(
      sq,
      V.steps[V.BISHOP].concat([ [forward, 0] ]),
      "oneStep"
    );
  }

  getPotentialQueenMoves(sq) {
    return this.getSlideNJumpMoves(
      sq,
      V.steps[V.BISHOP],
      "oneStep"
    );
  }

  getAllValidMoves() {
    if (this.movesCount >= 2) return super.getAllValidMoves();
    const color = this.turn;
    let moves = [];
    for (let i = 0; i < V.RESERVE_PIECES.length; i++) {
      moves = moves.concat(
        this.getPotentialMovesFrom([V.size.x + (color == "w" ? 0 : 1), i])
      );
    }
    return this.filterValid(moves);
  }

  isAttackedByBishop(sq, color) {
    const forward = (this.turn == 'w' ? 1 : -1);
    return this.isAttackedBySlideNJump(
      sq,
      color,
      V.BISHOP,
      V.steps[V.BISHOP].concat([ [forward, 0] ]),
      "oneStep"
    );
  }

  isAttackedByQueen(sq, color) {
    return this.isAttackedBySlideNJump(
      sq,
      color,
      V.QUEEN,
      V.steps[V.BISHOP],
      "oneStep"
    );
  }

  underCheck(color) {
    if (this.movesCount <= 1) return false;
    return super.underCheck(color);
  }

  play(move) {
    const color = move.appear[0].c;
    if (this.movesCount <= 1) {
      V.PlayOnBoard(this.board, move);
      const piece = move.appear[0].p;
      this.reserve[color][piece]--;
      if (piece == V.KING) this.kingPos[color] = [move.end.x, move.end.y];
      if (this.subTurn == 8) {
        // All placement moves are done
        this.movesCount++;
        this.turn = V.GetOppCol(color);
        if (this.movesCount == 1) this.subTurn = 1;
        else {
          // Initial placement is over
          delete this["reserve"];
          delete this["subTurn"];
        }
      }
      else this.subTurn++;
    }
    else super.play(move);
  }

  undo(move) {
    const color = move.appear[0].c;
    if (this.movesCount <= 2) {
      V.UndoOnBoard(this.board, move);
      const piece = move.appear[0].p;
      if (piece == V.KING) this.kingPos[color] = [-1, -1];
      if (!this.subTurn || this.subTurn == 1) {
        // All placement moves are undone (if any)
        if (!this.subTurn) this.re_setReserve(8);
        else this.subTurn = 8;
        this.movesCount--;
        this.turn = color;
      }
      else this.subTurn--;
      this.reserve[color][piece]++;
    }
    else super.undo(move);
  }

  getCheckSquares() {
    if (this.movesCount <= 1) return [];
    return super.getCheckSquares();
  }

  getCurrentScore() {
    if (this.movesCount <= 1) return "*";
    return super.getCurrentScore();
  }

  static get VALUES() {
    return {
      p: 1,
      r: 5,
      n: 3,
      b: 3,
      q: 2,
      k: 1000
    };
  }

  getComputerMove() {
    if (this.movesCount >= 2) return super.getComputerMove();
    // Play a random "initialization move"
    let res = [];
    for (let i=0; i<8; i++) {
      const moves = this.getAllValidMoves();
      const moveIdx = randInt(moves.length);
      this.play(moves[moveIdx]);
      res.push(moves[moveIdx]);
    }
    for (let i=7; i>=0; i--) this.undo(res[i]);
    return res;
  }

  getNotation(move) {
    // Do not note placement moves (complete move would be too long)
    if (move.vanish.length == 0) return "";
    if (move.appear[0].p != move.vanish[0].p) {
      // Pawn promotion: indicate correct final square
      const initSquare =
        V.CoordsToSquare({ x: move.vanish[0].x, y: move.vanish[0].y })
      const destSquare =
        V.CoordsToSquare({ x: move.appear[0].x, y: move.appear[0].y })
      const prefix = (initSquare != destSquare ? initSquare : "");
      return prefix + destSquare + "=Q";
    }
    return super.getNotation(move);
  }
};