xchess/lib/move.js

Chess Engine

export {
	Move,
	Capture,
	PawnDoubleMove,
	Castling,
	KingsideCastling,
	QueensideCastling,
	EnPassant,
	Promotion,
	CaptureAndPromotion,
	PromotionRequest,
	CaptureAndPromotionRequest,
}

import {Square} from './square.js'
import {Piece, Queen, Rook, Bishop, Knight, Pawn} from './piece.js'
import {GetMoveDisambiguation, SetMoveDisambiguation, DISAMBIGUATION_NONE, DISAMBIGUATION_FILE, DISAMBIGUATION_RANK, DISAMBIGUATION_FULL} from './move-disambiguator.js'
import {INVALID_PIECE_TYPE, MOVE_PROMOTION_NOT_AVAILABLE} from './errors.js'
import {MoveEvent, InsertEvent, DeleteEvent, TransferEvent} from './events.js'

function code(from, to){
	return from << 6 | to;
}

function iccf(from, to){
	return from.iccf + to.iccf;
}

function IS_PROMOTION_PIECE(piece){
	return [Queen, Rook, Bishop, Knight].some(Type => Type.is(piece));
}

function PROMOTION_PIECE(value, color){
	const piece = Piece.fromColor(value, color);
	if(!IS_PROMOTION_PIECE(piece))
		throw INVALID_PIECE_TYPE(piece);
	return piece;
}

class Move {

	static code(from, to){
		return code(Square.from(from), Square.from(to));
	}

	static is(value){
		return value instanceof this;
	}

	#code;
	#target;
	#from;
	#to;

	constructor(target, from, to){
		this.#target = Piece.from(target);
		this.#from = Square.from(from);
		this.#to = Square.from(to);
		this.#code = code(this.from, this.to);
	}

	get code(){
		return this.#code;
	}

	get iccf(){
		return iccf(this.from, this.to);
	}

	get target(){
		return this.#target;
	}

	get from(){
		return this.#from;
	}

	get to(){
		return this.#to;
	}

	get color(){
		return this.#target.color;
	}

	get kc(){
		return false;
	}

	get qc(){
		return false;
	}

	get disambiguation(){
		return GetMoveDisambiguation(this);
	}

	get fromHint(){
		switch(this.disambiguation){
			case DISAMBIGUATION_NONE:
				return '';
			case DISAMBIGUATION_FILE:
				return this.from.file.toString();
			case DISAMBIGUATION_RANK:
				return this.from.rank.toString();
		}	return this.from.toString();
	}

	valueOf(){
		return this.code;
	}

	toString({pieceLetter = true} = {}){
		if(pieceLetter)
			return `${this.target.moveLetter}${this.fromHint}${this.to}`;
		return `${this.fromHint}${this.to}`;
	}

	// stat

	match(cond){
		const {kc, qc, to, from, file, rank, char, sign, capture, promotion} = cond;
		if(kc && !this.kc)
			return false;
		if(qc && !this.qc)
			return false;
		if(to && !this.to.eq(to))
			return false;
		if(from && !this.from.eq(from))
			return false;
		if(rank && (this.from.rank !== rank))
			return false;
		if(file && (this.from.file !== file))
			return false;
		if(char && (this.target.char !== char))
			return false;
		if(sign && (this.target.sign !== sign))
			return false;
		if(capture && !this.capture)
			return false;
		if(promotion && !this.isPromotionRequest)
			return false;
		return true;
	}

	resolve(cond){
		if(this.match(cond)){
			if(cond.promotion)
				return this.promote(cond.promotion);
			return this;
		}	return null;
	}

	// rules

	get isIdle(){
		return !Pawn.is(this.target);
	}

	get doubleMovePawn(){
		return null;
	}

	get isPromotionRequest(){
		return false;
	}

	check(board){
		this.next(board);
		const check = board.check(this.color);
		this.prev(board);
		return check;
	}

	includes(piece){
		return this.target === piece;
	}

	promote(piece){
		throw MOVE_PROMOTION_NOT_AVAILABLE(this);
	}

	// board

	next(board){
		board.set(this.to, this.target);
	}

	prev(board){
		board.set(this.from, this.target);
	}

	// context

	do(context){
		this.next(context.board);
	}

	redo(context){
		this.next(context.board);
	}

	undo(context){
		this.prev(context.board);
	}

	trigger(context){
		context.dispatch(new TransferEvent(this.target, this.from, this.to));
	}
}

class Capture extends Move {

	#capture;

	constructor(target, from, to, capture){
		super(target, from, to);
		this.#capture = Piece.from(capture);
	}

	get capture(){
		return this.#capture;
	}

	get captureAt(){
		return this.to;
	}

	get fromHint(){
		if(Pawn.is(this.target))
			return this.from.file.toString();
		return super.fromHint;
	}

	toString({pieceLetter = true} = {}){
		if(pieceLetter)
			return `${this.target.moveLetter}${this.fromHint}x${this.to}`;
		return `${this.fromHint}x${this.to}`;
	}

	// rules

	get isIdle(){
		return false;
	}

	includes(piece){
		if(this.target === piece)
			return true;
		if(this.capture === piece)
			return true;
		return false;
	}

	// Board

	prev(board){
		board.set(this.from, this.target);
		board.set(this.captureAt, this.capture);
	}

	// Context

	do(context){
		this.next(context.board);
		context.captureList.add(this.capture);
	}

	redo(context){
		this.next(context.board);
		context.captureList.add(this.capture);
	}

	undo(context){
		this.prev(context.board);
		context.captureList.delete(this.capture);
	}

	trigger(context){
		context.dispatch(new TransferEvent(this.target, this.from, this.to));
		context.dispatch(new DeleteEvent(this.capture, this.captureAt));
		context.dispatch(new MoveEvent('capture', this));
	}
}

class PawnDoubleMove extends Move {

	get doubleMovePawn(){
		return this.target;
	}
}

class Castling extends Move {

	#submove;

	constructor(target, from, to, submove){
		super(target, from, to);
		this.#submove = submove;
	}

	get submove(){
		return this.#submove;
	}

	// Board

	next(board){
		super.next(board);
		this.submove.next(board);
	}

	prev(board){
		this.submove.prev(board);
		super.prev(board);
	}

	// Rules

	includes(piece){
		if(super.includes(piece))
			return true;
		if(this.submove.includes(piece))
			return true;
		return false;
	}

	// Context

	trigger(context){
		context.dispatch(new TransferEvent(this.target, this.from, this.to));
		context.dispatch(new TransferEvent(this.submove.target, this.submove.from, this.submove.to));
		context.dispatch(new MoveEvent('castling', this));
	}
}

class KingsideCastling extends Castling {

	get kc(){
		return true;
	}

	toString(){
		return '0-0';
	}
}

class QueensideCastling extends Castling {

	get qc(){
		return true;
	}

	toString(){
		return '0-0-0';
	}
}

class EnPassant extends Capture {

	#captureAt;

	constructor(target, from, to, capture, captureAt){
		super(target, from, to, capture);
		this.#captureAt = Square.from(captureAt);
	}

	get captureAt(){
		return this.#captureAt;
	}

	toString(args){
		return `${super.toString(args)} e.p.`;
	}

	// Board

	next(board){
		board.delete(this.captureAt);
		board.set(this.to, this.target);
	}

	// Context

	trigger(context){
		super.trigger(context);
		context.dispatch(new MoveEvent('enpassant', this));
	}
}

class PromotionRequest extends Move {

	get isPromotionRequest(){
		return true;
	}

	respond(pieceVal){
		const piece = PROMOTION_PIECE(pieceVal, this.color);
		const {target, from, to, disambiguation} = this;
		const move = new PromotionResponse(target, from, to, piece);
		SetMoveDisambiguation(move, disambiguation);
		return move;
	}

	promote(pieceVal){
		const piece = PROMOTION_PIECE(pieceVal, this.color);
		const {target, from, to, disambiguation} = this;
		const move = new Promotion(target, from, to, piece);
		SetMoveDisambiguation(move, disambiguation);
		return move;
	}
}

class CaptureAndPromotionRequest extends Capture {

	get isPromotionRequest(){
		return true;
	}

	respond(pieceVal){
		const piece = PROMOTION_PIECE(pieceVal, this.color);
		const {target, from, to, capture, disambiguation} = this;
		const move = new CaptureAndPromotionResponse(target, from, to, capture, piece);
		SetMoveDisambiguation(move, disambiguation);
		return move;
	}

	promote(pieceVal){
		const piece = PROMOTION_PIECE(pieceVal, this.color);
		const {target, from, to, capture, disambiguation} = this;
		const move = new CaptureAndPromotion(target, from, to, capture, piece);
		SetMoveDisambiguation(move, disambiguation);
		return move;
	}
}

class Promotion extends Move {

	#promoteTo;

	constructor(target, from, to, promoteTo){
		super(target, from, to);
		this.#promoteTo = Piece.from(promoteTo);
	}

	get promoteTo(){
		return this.#promoteTo;
	}

	toString(args){
		return `${super.toString(args)}/${this.promoteTo.moveLetter}`;
	}

	// Board

	next(board){
		board.delete(this.from);
		board.set(this.to, this.promoteTo);
	}

	prev(board){
		board.delete(this.to);
		board.set(this.from, this.target);
	}

	// Context

	trigger(context){
		super.trigger(context);
		context.dispatch(new DeleteEvent(this.target, this.to));
		context.dispatch(new InsertEvent(this.promoteTo, this.to));
	}
}

class CaptureAndPromotion extends Capture {

	#promoteTo;

	constructor(target, from, to, capture, promoteTo){
		super(target, from, to, capture);
		this.#promoteTo = Piece.from(promoteTo);
	}

	get promoteTo(){
		return this.#promoteTo;
	}

	toString(args){
		return `${super.toString(args)}/${this.promoteTo.moveLetter}`;
	}

	// Board

	next(board){
		board.delete(this.from);
		board.set(this.to, this.promoteTo);
	}

	prev(board){
		board.set(this.from, this.target);
		board.set(this.captureAt, this.capture);
	}

	// Context

	trigger(context){
		super.trigger(context);
		context.dispatch(new DeleteEvent(this.target, this.to));
		context.dispatch(new InsertEvent(this.promoteTo, this.to));
	}
}

class PromotionResponse extends Promotion {

	// Context

	do(context){
		context.board.set(this.to, this.promoteTo);
	}

	trigger(context){
		context.dispatch(new DeleteEvent(this.target, this.to));
		context.dispatch(new InsertEvent(this.promoteTo, this.to));
	}
}

class CaptureAndPromotionResponse extends CaptureAndPromotion {

	// Context

	do(context){
		context.board.set(this.to, this.promoteTo);
	}

	trigger(context){
		context.dispatch(new DeleteEvent(this.target, this.to));
		context.dispatch(new InsertEvent(this.promoteTo, this.to));
	}
}