tic-tac-toe-ws/server.mts

import { Message, Response, Hello, EndGame } from "common.mjs"
import { WebSocket, WebSocketServer } from "ws";

const port = 1234
const wss = new WebSocketServer({ port });

let grid = [0, 0, 0, 0, 0, 0, 0, 0, 0]

console.log(`waiting for connection on ws://localhost:${port}`);

interface Client {
    id: number,
    ws: WebSocket
}

let id = 1;
let clients: Client[] = [];
let currentPlayerId: number | undefined = undefined;

wss.on("connection", (ws) => {
    id += 1;
    if (clients.length == 2) {
        console.log("too many players");
        ws.close();
        return;
    }

    if (!currentPlayerId) {
	currentPlayerId = id;
	console.log(`current player is #${currentPlayerId}`);
    }

    clients.push({id, ws});
    ws.send(JSON.stringify({kind: "hello", data: { id } as Hello}));
    console.log(`player #${id} connected`);

    ws.addEventListener("message", (event: any) => {
        const message = JSON.parse(event.data);
        const {x, y} = message;
        const playerId = clients.find(x => x.ws === ws)?.id;
        console.assert(playerId);
	console.log(message, playerId, currentPlayerId);

	if (playerId != currentPlayerId) {
	    return;
	}

        if (grid[y*3+x] === 0) {
            grid[y*3+x] = playerId as number;
            for (const c of clients) {
                const msg: Message = {
                    kind: "update",
		    data: { grid } as Response,
		}
		c.ws.send(JSON.stringify(msg));
	    }

	    const winnerId = checkWin(grid);
	    if (winnerId == -1) {
	        currentPlayerId = clients.find(x => x.id !== currentPlayerId)?.id; // change player
		console.assert(currentPlayerId);
		console.log(`current player is #${currentPlayerId}`);
	    } else if (winnerId == 0) {
		for (const c of clients) {
                     const msg: Message = {
		         kind: "endgame",
			 data: { issue: "draw" } as EndGame
		     };
		     c.ws.send(JSON.stringify(msg));
		}
	    } else {
	        console.log(`player ${winnerId} won !`);

		const winner = clients.find(x => x.id === winnerId);
	        winner?.ws?.send(JSON.stringify({
		    kind: "endgame",
		    data: { issue: "win" } as EndGame
		} as Message));	

		const loser = clients.find(x => x.id !== winnerId);
	        loser?.ws?.send(JSON.stringify({
		    kind: "endgame",
		    data: { issue: "lose" } as EndGame
		} as Message));	
	    }
	}
    });

    ws.on("close", () => {
        console.log(`player #${id} disconnected`);
        clients = clients.filter(x => x.id !== id);
    });
});

function checkWin(grid: number[]): number {
	const clone = [...grid];
	const grid2d = [];
	while(clone.length) grid2d.push(clone.splice(0,3));

	if (
		grid2d[0][0] !== 0 &&
		grid2d[0][0] === grid2d[0][1] &&
		grid2d[0][1] === grid2d[0][2]
	) {
		return grid2d[0][0];
	}
	if (
		grid2d[1][0] !== 0 &&
		grid2d[1][0] === grid2d[1][1] &&
	grid2d[1][1] === grid2d[1][2]
	) {
		return grid2d[1][0];
	}
	if (
		grid2d[2][0] !== 0 &&
		grid2d[2][0] === grid2d[2][1] &&
	grid2d[2][1] === grid2d[2][2]
	) {
		return grid2d[2][0];
	}
	if (
		grid2d[0][0] !== 0 &&
		grid2d[0][0] === grid2d[1][0] &&
	grid2d[1][0] === grid2d[2][0]
	) {
		return grid2d[0][0];
	}
	if (
		grid2d[0][1] !== 0 &&
		grid2d[0][1] === grid2d[1][1] &&
	grid2d[1][1] === grid2d[2][1]
	) {
		return grid2d[0][1];
	}
	if (
		grid2d[0][2] !== 0 &&
		grid2d[0][2] === grid2d[1][2] &&
	grid2d[1][2] === grid2d[2][2]
	) {
		return grid2d[0][2];
	}
	if (
		grid2d[0][0] !== 0 &&
		grid2d[0][0] === grid2d[1][1] &&
	grid2d[1][1] === grid2d[2][2]
	) {
		return grid2d[0][0];
	}
	if (
		grid2d[0][2] !== 0 &&
		grid2d[0][2] === grid2d[1][1] &&
	grid2d[1][1] === grid2d[2][0]
	) {
		return grid2d[0][2];
	}
	for (const row of grid2d) {
		if (row[0] === 0 || row[1] === 0 || row[2] === 0) {
			return -1;
		}
	}
	return 0;
}