Add autodiscovery for Jellyfin servers (#1146)

* Add autodiscovery for Jellyfin servers

* Remove debugging aids

you didn't see anything

* Fix linter errors

* Send a discovery packet to localhost too

src/preload/autodiscover.ts

@@ -0,0 +1,23 @@
+import { ipcRenderer } from 'electron';
+
+import { DiscoveredServerItem } from '../shared/types/types';
+
+const discover = (onReply: (server: DiscoveredServerItem) => void): Promise<void> => {
+    const { port1: local, port2: remote } = new MessageChannel();
+
+    ipcRenderer.postMessage('autodiscover-ping', {}, [remote]);
+
+    local.onmessage = (ev) => {
+        onReply(ev.data);
+    };
+
+    return new Promise<void>((resolve) => {
+        local.addEventListener('close', () => resolve());
+    });
+};
+
+export const autodiscover = {
+    discover,
+};
+
+export type AutoDiscover = typeof autodiscover;

src/preload/index.ts

@@ -1,6 +1,7 @@
 import { electronAPI } from '@electron-toolkit/preload';
 import { contextBridge } from 'electron';
 
+import { autodiscover } from './autodiscover';
 import { browser } from './browser';
 import { discordRpc } from './discord-rpc';
 import { ipc } from './ipc';
@@ -13,6 +14,7 @@ import { utils } from './utils';
 
 // Custom APIs for renderer
 const api = {
+    autodiscover,
     browser,
     discordRpc,
     ipc,