svelte4-chess/dist/engine.js

Fully playable chess component for Svelte 4. Powered by Chess.js logic, Chessground chessboard and optionally Stockfish chess AI.

;
var State;
(function (State) {
    State["Uninitialised"] = "uninitialised";
    State["Initialising"] = "initialising";
    State["Waiting"] = "waiting";
    State["Searching"] = "searching";
})(State || (State = {}));
;
export class Engine {
    stockfish;
    state = State.Uninitialised;
    moveTime;
    depth;
    color;
    stockfishPath;
    externalUciCallback = undefined;
    // Callbacks used when waiting for specific UCI messages
    onUciOk = undefined; // "uciok" marks end of initialisation
    onBestMove = undefined; // "uciok", used during initialisation
    // Constructor
    constructor(options = {}) {
        this.moveTime = options.moveTime || 2000;
        this.depth = options.depth || 40;
        this.color = options.color || 'b';
        this.stockfishPath = options.stockfishPath || 'stockfish.js';
    }
    // Initialise Stockfish. Resolve promise after receiving uciok.
    init() {
        return new Promise((resolve) => {
            this.state = State.Initialising;
            // NOTE: stockfish.js is not part of the npm package due to its size (1-2 MB).
            // You can find the file here: https://github.com/gtim/svelte-chess/tree/main/static
            this.stockfish = new Worker(this.stockfishPath);
            this.stockfish.addEventListener('message', (e) => this._onUci(e));
            this.onUciOk = () => {
                if (this.state === State.Initialising) {
                    this.state = State.Waiting;
                    this.onUciOk = undefined;
                    resolve();
                }
            };
            this.stockfish.postMessage('uci');
        });
    }
    // Callback when receiving UCI messages from Stockfish.
    _onUci({ data }) {
        const uci = data;
        if (this.onUciOk && uci === 'uciok') {
            this.onUciOk();
        }
        if (this.onBestMove && uci.slice(0, 8) === 'bestmove') {
            this.onBestMove(uci);
        }
        if (this.externalUciCallback) {
            this.externalUciCallback(uci);
        }
    }
    setUciCallback(callback) {
        this.externalUciCallback = callback;
    }
    getMove(fen) {
        return new Promise((resolve) => {
            if (!this.stockfish)
                throw new Error('Engine not initialised');
            if (this.state !== State.Waiting)
                throw new Error('Engine not ready (state: ' + this.state + ')');
            this.state = State.Searching;
            this.stockfish.postMessage('position fen ' + fen);
            this.stockfish.postMessage(`go depth ${this.depth} movetime ${this.moveTime}`);
            this.onBestMove = (uci) => {
                const uciArray = uci.split(' ');
                const bestMoveLan = uciArray[1];
                this.state = State.Waiting;
                this.onBestMove = undefined;
                resolve(bestMoveLan);
            };
        });
    }
    getColor() {
        return this.color;
    }
    isSearching() {
        return this.state === State.Searching;
    }
    async stopSearch() {
        return new Promise((resolve) => {
            if (!this.stockfish)
                throw new Error('Engine not initialised');
            if (this.state !== State.Searching)
                resolve();
            this.onBestMove = (uci) => {
                this.state = State.Waiting;
                this.onBestMove = undefined;
                resolve();
            };
            this.stockfish.postMessage('stop');
        });
    }
}