Set up server to relay ripples and presence info

server/index.ts

@@ -0,0 +1,65 @@
+import { type ServerWebSocket } from "bun"
+
+type WebsocketData = {
+  clientId: string
+}
+
+type Message =
+  | { type: 'presence-information', others: number }
+  | { type: 'ripple', position: [number, number], maxRadius: number }
+
+const clients: Map<WebsocketData['clientId'], ServerWebSocket<WebsocketData>> = new Map()
+
+const server = Bun.serve<WebsocketData>({
+  fetch(req, server) {
+    // TODO Allow creating private ponds
+    server.upgrade(req, {
+      data: {
+        clientId: crypto.randomUUID()
+      }
+    })
+  },
+  websocket: {
+    open(ws) {
+      // register newly connected client and tell them how many other people are there
+      console.log('Connection opened', ws.data.clientId)
+      clients.set(ws.data.clientId, ws)
+      const enterNotice = JSON.stringify(<Message>{
+        type: 'presence-information',
+        others: clients.size,
+      })
+      for (const [uuid, client] of clients.entries()) {
+        if (uuid !== ws.data.clientId) {
+          client.send(enterNotice, true)
+        }
+      }
+    },
+    message(ws, message) {
+      // broadcast message to all other clients
+      // TODO: Validate message shape
+      const msg = JSON.parse(`${message}`)
+      console.log('Relaying message from', ws.data.clientId, msg)
+      for (const [uuid, client] of clients.entries()) {
+        if (uuid !== ws.data.clientId) {
+          client.send(message)
+        }
+      }
+    },
+    close(ws, code, reason) {
+      // remove client from list of registered clients and tell other clients how many people are there
+      console.log('Connection closed', ws.data.clientId)
+      clients.delete(ws.data.clientId)
+      const leaveNotice = JSON.stringify(<Message>{
+        type: 'presence-information',
+        others: clients.size,
+      })
+      for (const [uuid, client] of clients.entries()) {
+        if (uuid !== ws.data.clientId) {
+          client.send(leaveNotice, true)
+        }
+      }
+    }
+  },
+})
+
+console.log(`Server running on ${server.hostname}:${server.port}`)