implement the game, more or less

client.mts

@@ -1,4 +1,4 @@
-import { Request, Response, Message, Hello } from "common.mjs";
+import { Request, Response, Message, Hello, EndGame } from "common.mjs";
 
 const ws = new WebSocket("ws://localhost:1234");
 const grid = [0, 0, 0, 0, 0, 0, 0, 0, 0]
@@ -44,6 +44,19 @@ ws.onmessage = (evt) => {
             }
             break;
         }
+	case "endgame": {
+            const h1 = document.getElementById("title") as HTMLHeadingElement | null;
+            if (h1) {
+		const issue = (msg.data as EndGame).issue;
+		switch (issue){
+	            case "win": h1.innerText = "you won"; break;
+		    case "lose": h1.innerText = "you lose"; break;
+		    case "draw": h1.innerText = "it's a draw!"; break;
+		    default: throw new Error(`unexpected ${issue}`);
+		}
+	    }
+	    break;
+	}
         default: {
             console.log(msg);
             break;

common.mts

@@ -1,8 +1,8 @@
-export type MessageKind = "hello" | "update";
+export type MessageKind = "hello" | "update" | "endgame";
 
 export interface Message {
 	kind: MessageKind,
-	data: Response | Hello,
+	data: Response | Hello | EndGame,
 }
 
 export interface Request {
@@ -18,3 +18,6 @@ export interface Hello {
     id: number
 }
 
+export interface EndGame {
+    issue: "win" | "lose" | "draw"
+}

server.mts

@@ -1,4 +1,4 @@
-import { Message, Response, Hello } from "common.mjs"
+import { Message, Response, Hello, EndGame } from "common.mjs"
 import { WebSocket, WebSocketServer } from "ws";
 
 const port = 1234
@@ -15,6 +15,7 @@ interface Client {
 
 let id = 1;
 let clients: Client[] = [];
+let currentPlayerId: number | undefined = undefined;
 
 wss.on("connection", (ws) => {
     id += 1;
@@ -24,6 +25,11 @@ wss.on("connection", (ws) => {
         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`);
@@ -33,16 +39,51 @@ wss.on("connection", (ws) => {
         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,
+		    data: { grid } as Response,
-                }
+		}
-                c.ws.send(JSON.stringify(msg));
+		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", () => {
@@ -50,3 +91,72 @@ wss.on("connection", (ws) => {
         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;
+}