add server sent events endpoint

Author: menduz

package.json

@@ -17,7 +17,7 @@
   },
   "dependencies": {
     "@well-known-components/env-config-provider": "^1.1.1",
-    "@well-known-components/http-server": "^1.1.6-20220927190058.commit-2dfb235",
+    "@well-known-components/http-server": "^2.0.0",
     "@well-known-components/interfaces": "^1.4.1",
     "@well-known-components/logger": "^3.1.2",
     "@well-known-components/metrics": "^2.0.1-20220909150423.commit-8f7e5bc"

src/controllers/routes.ts

@@ -1,12 +1,41 @@
 import { Router } from "@well-known-components/http-server"
-import { GlobalContext } from "../types"
+import { GlobalContext, HandlerContextWithPath } from "../types"
 import { pingHandler } from "./handlers/ping-handler"
+import { Readable } from "node:stream"
 
 // We return the entire router because it will be easier to test than a whole server
 export async function setupRouter(globalContext: GlobalContext): Promise<Router<GlobalContext>> {
   const router = new Router<GlobalContext>()
 
   router.get("/ping", pingHandler)
+  router.get("/sse", async function (ctx: Pick<HandlerContextWithPath<"metrics", "/sse">, "url" | "components">) {
+    const stream = new Readable({
+      read() {
+        // this fn is called every time the readable "needs" a message
+      },
+      construct() {
+        console.log('constructed')
+        setInterval(() => this.push(`data: ${JSON.stringify({ now: performance.now() })}\n\n`), 1500)
+      },
+      destroy() {
+        console.log('destroyed')
+      }
+    })
+    
+    
+
+    // Tell the client to retry every 10 seconds if connectivity is lost
+    stream.push('retry: 10000\n\n');
+
+    return {
+      headers: {
+        'Cache-Control': 'no-cache',
+        'Content-Type': 'text/event-stream',
+        'Connection': 'keep-alive'
+      },
+      body: stream
+    }
+  })
 
   return router
 }