shogiops/src/notation/kitao-kawasaki.ts

Shogi rules and operations

import type { MoveOrDrop, Square } from '../types.js';
import { defined, isDrop } from '../util.js';
import type { Position } from '../variant/position.js';
import { pieceCanPromote } from '../variant/util.js';
import { aimingAt, makeNumberSquare, roleKanjiDuplicates, roleToKanji } from './util.js';

// 歩-76
export function makeKitaoKawasakiMoveOrDrop(
  pos: Position,
  md: MoveOrDrop,
  lastDest?: Square,
): string | undefined {
  if (isDrop(md)) {
    return roleToKanji(md.role) + '*' + makeNumberSquare(md.to);
  } else {
    const piece = pos.board.get(md.from);
    if (piece) {
      const roleStr = roleToKanji(piece.role).replace('成', '+'),
        ambStr = aimingAt(
          pos,
          pos.board
            .roles(piece.role, ...roleKanjiDuplicates(pos.rules)(piece.role))
            .intersect(pos.board.color(piece.color)),
          md.to,
        )
          .without(md.from)
          .isEmpty()
          ? ''
          : `(${makeNumberSquare(md.from)})`,
        toCapture = pos.board.get(md.to),
        actionStr = toCapture ? 'x' : '-';
      if (defined(md.midStep)) {
        const midCapture = pos.board.get(md.midStep),
          igui = !!midCapture && md.to === md.from;
        if (igui) return `${roleStr}${ambStr}x!${makeNumberSquare(md.midStep)}`;
        else if (md.to === md.from) return `--`;
        else
          return `${roleStr}${ambStr}${midCapture ? 'x' : '-'}${makeNumberSquare(
            md.midStep,
          )}${actionStr}${makeNumberSquare(md.to)}`;
      } else {
        const destStr =
            (lastDest ?? pos.lastMoveOrDrop?.to) === md.to ? '' : makeNumberSquare(md.to),
          promStr = md.promotion
            ? '+'
            : pieceCanPromote(pos.rules)(piece, md.from, md.to, toCapture)
              ? '='
              : '';
        return `${roleStr}${ambStr}${actionStr}${destStr}${promStr}`;
      }
    } else return undefined;
  }
}