feat: add simple app ping (#580)

* feat: add simple ping

* refactor: make ping run on server and show errors

* fix: format issues

* fix: missing translation for enabled ping option for app

* refactor: remove ping queue as no longer needed

* chore: address pull request feedback

* test: add some unit tests

* fix: format issues

* fix: deepsource issues

packages/api/src/router/widgets/app.ts

@@ -0,0 +1,42 @@
+import { observable } from "@trpc/server/observable";
+
+import { sendPingRequestAsync } from "@homarr/ping";
+import { pingChannel, pingUrlChannel } from "@homarr/redis";
+import { z } from "@homarr/validation";
+
+import { createTRPCRouter, publicProcedure } from "../../trpc";
+
+export const appRouter = createTRPCRouter({
+  ping: publicProcedure.input(z.object({ url: z.string() })).query(async ({ input }) => {
+    const pingResult = await sendPingRequestAsync(input.url);
+
+    return {
+      url: input.url,
+      ...pingResult,
+    };
+  }),
+  updatedPing: publicProcedure
+    .input(
+      z.object({
+        url: z.string(),
+      }),
+    )
+    .subscription(async ({ input }) => {
+      await pingUrlChannel.addAsync(input.url);
+
+      const pingResult = await sendPingRequestAsync(input.url);
+
+      return observable<{ url: string; statusCode: number } | { url: string; error: string }>((emit) => {
+        emit.next({ url: input.url, ...pingResult });
+        pingChannel.subscribe((message) => {
+          // Only emit if same url
+          if (message.url !== input.url) return;
+          emit.next(message);
+        });
+
+        return () => {
+          void pingUrlChannel.removeAsync(input.url);
+        };
+      });
+    }),
+});