chess/docs/implementation/code-templates/js/models/Board.js

/**
 * @file Board.js
 * @description Represents the chess board and manages piece positions
 * @author Implementation Team
 */

import { BOARD_SIZE, COLORS, INITIAL_POSITIONS } from '../utils/Constants.js';
import { isValidPosition, algebraicToPosition } from '../utils/Helpers.js';
import Pawn from './pieces/Pawn.js';
import Rook from './pieces/Rook.js';
import Knight from './pieces/Knight.js';
import Bishop from './pieces/Bishop.js';
import Queen from './pieces/Queen.js';
import King from './pieces/King.js';

/**
 * @class Board
 * @description Manages the 8x8 chess board and piece positions
 *
 * @example
 * const board = new Board();
 * board.reset();  // Setup initial position
 * const piece = board.getPieceAt({row: 0, col: 0});
 */
class Board {
  constructor() {
    /**
     * @property {Array<Array<Piece|null>>} _squares - 2D array representing the board
     */
    this._squares = this._createEmptyBoard();

    /**
     * @property {Map<string, Piece>} _pieces - Map of all pieces (for quick lookup)
     * Key format: "color-type-index" (e.g., "white-pawn-0")
     */
    this._pieces = new Map();
  }

  /**
   * Creates an empty 8x8 board
   *
   * @private
   * @returns {Array<Array<null>>} Empty board array
   */
  _createEmptyBoard() {
    // TODO: Implement empty board creation
    // Create 8x8 array filled with null
    return [];
  }

  /**
   * Gets the piece at a specific position
   *
   * @param {Object} position - Position {row, col}
   * @returns {Piece|null} Piece at position or null if empty
   * @throws {Error} If position is invalid
   *
   * @example
   * const piece = board.getPieceAt({row: 0, col: 0});
   */
  getPieceAt(position) {
    // TODO: Implement get piece
    // 1. Validate position
    // 2. Return piece at position or null
    return null;
  }

  /**
   * Sets a piece at a specific position
   *
   * @param {Object} position - Position {row, col}
   * @param {Piece|null} piece - Piece to place or null to clear
   * @throws {Error} If position is invalid
   *
   * @example
   * board.setPieceAt({row: 4, col: 4}, new Pawn('white', {row: 4, col: 4}));
   */
  setPieceAt(position, piece) {
    // TODO: Implement set piece
    // 1. Validate position
    // 2. Update _squares array
    // 3. Update piece's position property
    // 4. Update _pieces map if needed
  }

  /**
   * Removes a piece from a specific position
   *
   * @param {Object} position - Position {row, col}
   * @returns {Piece|null} Removed piece or null if position was empty
   *
   * @example
   * const captured = board.removePieceAt({row: 4, col: 4});
   */
  removePieceAt(position) {
    // TODO: Implement remove piece
    // 1. Get piece at position
    // 2. Set position to null
    // 3. Update _pieces map
    // 4. Return removed piece
    return null;
  }

  /**
   * Moves a piece from one position to another
   *
   * @param {Object} from - Starting position {row, col}
   * @param {Object} to - Target position {row, col}
   * @returns {Piece|null} Captured piece or null
   * @throws {Error} If no piece at 'from' position
   *
   * @example
   * const captured = board.movePiece({row: 6, col: 4}, {row: 4, col: 4});
   */
  movePiece(from, to) {
    // TODO: Implement move piece
    // 1. Get piece at 'from'
    // 2. Throw error if no piece
    // 3. Get piece at 'to' (captured piece)
    // 4. Remove piece from 'from'
    // 5. Place piece at 'to'
    // 6. Update piece's position
    // 7. Return captured piece
    return null;
  }

  /**
   * Gets all pieces on the board
   *
   * @returns {Array<Piece>} Array of all pieces
   *
   * @example
   * const allPieces = board.getAllPieces();
   * console.log(allPieces.length);  // Should be 32 at game start
   */
  getAllPieces() {
    // TODO: Implement get all pieces
    // Iterate through _squares and collect all non-null pieces
    return [];
  }

  /**
   * Gets all pieces of a specific color
   *
   * @param {string} color - Color to filter by ('white' or 'black')
   * @returns {Array<Piece>} Array of pieces of the specified color
   *
   * @example
   * const whitePieces = board.getPiecesByColor('white');
   */
  getPiecesByColor(color) {
    // TODO: Implement get pieces by color
    // Filter all pieces by color
    return [];
  }

  /**
   * Finds the king of a specific color
   *
   * @param {string} color - Color of the king ('white' or 'black')
   * @returns {Piece|null} King piece or null if not found
   *
   * @example
   * const whiteKing = board.getKing('white');
   */
  getKing(color) {
    // TODO: Implement get king
    // Find piece with type 'king' and matching color
    return null;
  }

  /**
   * Creates a deep copy of the board
   *
   * @returns {Board} Cloned board
   *
   * @example
   * const boardCopy = board.clone();
   */
  clone() {
    // TODO: Implement clone
    // 1. Create new Board instance
    // 2. Deep copy all pieces
    // 3. Maintain position references
    return null;
  }

  /**
   * Resets the board to initial chess position
   *
   * @example
   * board.reset();
   */
  reset() {
    // TODO: Implement reset
    // 1. Clear the board
    // 2. Use INITIAL_POSITIONS to create pieces
    // 3. Place each piece on the board

    // Helper: Create piece based on type
    const createPiece = (type, color, position) => {
      // TODO: Implement piece factory
      // Use switch/case or object map to create appropriate piece class
      return null;
    };

    // TODO: Iterate through INITIAL_POSITIONS for both colors
    // Create and place each piece
  }

  /**
   * Clears the entire board
   *
   * @example
   * board.clear();
   */
  clear() {
    // TODO: Implement clear
    this._squares = this._createEmptyBoard();
    this._pieces.clear();
  }

  /**
   * Checks if a position is occupied
   *
   * @param {Object} position - Position {row, col}
   * @returns {boolean} True if position has a piece
   *
   * @example
   * if (board.isOccupied({row: 4, col: 4})) {
   *   console.log('Square is occupied');
   * }
   */
  isOccupied(position) {
    // TODO: Implement is occupied
    return false;
  }

  /**
   * Checks if a position is occupied by an enemy piece
   *
   * @param {Object} position - Position {row, col}
   * @param {string} playerColor - Color of the current player
   * @returns {boolean} True if occupied by enemy piece
   *
   * @example
   * if (board.isOccupiedByEnemy({row: 4, col: 4}, 'white')) {
   *   console.log('Can capture');
   * }
   */
  isOccupiedByEnemy(position, playerColor) {
    // TODO: Implement is occupied by enemy
    // 1. Check if occupied
    // 2. Check if piece color is different from playerColor
    return false;
  }

  /**
   * Converts board to string representation (for debugging)
   *
   * @returns {string} String representation of the board
   *
   * @example
   * console.log(board.toString());
   */
  toString() {
    // TODO: Implement toString
    // Create ASCII representation of the board
    // Use piece symbols or letters
    return '';
  }
}

export default Board;