Plumb a game's ID value down into the base class

[empires-server] / game.js

diff --git a/game.js b/game.js
index 028c0393f9be02ac027922fa6b9244d70380608e..706bfc7a153353358d0064f0b15deed18f44f09e 100644 (file)
--- a/game.js
+++ b/game.js
@@ -1,8 +1,76 @@
 /* Base class providing common code for game engine implementations. */
 class Game {
-  constructor(name) {
-    this.name = name;
+  constructor(id) {
+    this.id = id;
+    this.clients = [];
+    this.next_client_id = 1;
   }
+
+  /* Suport for game meta-data.
+   *
+   * What we want here is an effectively static field that is
+   * accessible through either the class name (SomeGame.meta) or an
+   * instance (some_game.meta). To pull this off we do keep two copies
+   * of the data. But the game classes can just set SomeGame.meta once
+   * and then reference it either way.
+   */
+  static set meta(data) {
+    /* This allows class access (SomeGame.meta) via the get method below. */
+    this._meta = data;
+
+    /* While this allows access via an instance (some_game.meta). */
+    this.prototype.meta = data;
+  }
+
+  static get meta() {
+    return this._meta;
+  }
+
+  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'));
+  }
+
+  /* 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) {
+    /* 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 = this.add_client(response);
+
+    /* And queue up cleanup to be triggered on client close. */
+    request.on('close', () => {
+      this.remove_client(id);
+    });
+  }
+
 }
 
 module.exports = Game;