tictactoe: Replay previous moves when a new client connects

[empires-server] / tictactoe.js

diff --git a/tictactoe.js b/tictactoe.js
index 82c5f7e839d770cb4b4bb33f6f040ae9f079c6aa..6d4b0148a4a12afa4a5e8046fd3c8447d9d6729d 100644 (file)
--- a/tictactoe.js
+++ b/tictactoe.js
@@ -1,25 +1,15 @@
 const express = require("express");
-const cors = require("cors");
-const body_parser = require("body-parser");
-const path = require("path");
-const nunjucks = require("nunjucks");
-
-const app = express();
-app.use(cors());
-app.use(body_parser.urlencoded({ extended: false }));
-app.use(body_parser.json());
-
-nunjucks.configure("templates", {
-  autoescape: true,
-  express: app
-});
+const Game = require("./game.js");
+
+const engine_name = "tictactoe";
 
-class TicTacToe {
+const router = express.Router();
+
+class TicTacToe extends Game {
   constructor() {
+    super(engine_name);
     this.moves = [];
     this.board = Array(9).fill(null);
-    this.clients = [];
-    this.next_client_id = 1;
   }
 
   /* Returns Boolean indicating whether move was legal and added. */
@@ -34,39 +24,21 @@ class TicTacToe {
     return true;
   }
 
-  add_client(response) {
-    const id = this.next_client_id;
-    this.clients.push({id: id,
-                       response: response});
-    this.next_client_id++;
-
-    return id;
-  }
-
-  remove_client(id) {
-    this.clients = this.clients.filter(client => client.id !== id);
-  }
-
-  /* Send a string to all clients */
-  broadcast_string(str) {
-    this.clients.forEach(client => client.response.write(str + '\n'));
+  broadcast_move(square) {
+    this.broadcast_event("move", square);
   }
 
-  /* Send an event to all clients.
-   *
-   * An event has both a declared type and a separate data block.
-   * It also ends with two newlines (to mark the end of the event).
-   */
-  broadcast_event(type, data) {
-    this.broadcast_string(`event: ${type}\ndata: ${data}\n`);
-  }
+  handle_events(request, response) {
+    super.handle_events(request, response);
 
-  broadcast_move(square) {
-    this.broadcast_event("move", square);
+    /* When a new client joins, replay all previous moves to it. */
+    for (let move of this.moves) {
+      response.write(`event: move\ndata: ${move}\n\n`);
+    }
   }
 }
 
-app.get('/', (request, response) => {
+router.get('/', (request, response) => {
   const game = request.game;
 
   if (! request.session.nickname)
@@ -75,7 +47,7 @@ app.get('/', (request, response) => {
     response.render('tictactoe-game.html');
 });
 
-app.post('/move', (request, response) => {
+router.post('/move', (request, response) => {
   const game = request.game;
   const square = request.body.square;
 
@@ -91,26 +63,12 @@ app.post('/move', (request, response) => {
   game.broadcast_move(square);
 });
 
-app.get('/events', (request, response) => {
+router.get('/events', (request, response) => {
   const game = request.game;
 
-  /* These headers will keep the connection open so we can stream events. */
-  const headers = {
-    "Content-type": "text/event-stream",
-    "Connection": "keep-alive",
-    "Cache-Control": "no-cache"
-  };
-  response.writeHead(200, headers);
-
-  /* Add this new client to our list of clients. */
-  const id = game.add_client(response);
-
-  /* And queue up cleanup to be triggered on client close. */
-  request.on('close', () => {
-    game.remove_client(id);
-  });
+  game.handle_events(request, response);
 });
 
-exports.app = app;
-exports.name = "tictactoe";
+exports.router = router;
+exports.name = engine_name;
 exports.Game = TicTacToe;