feat: server discovery during login

hooks/useJellyfinDiscovery.tsx

@@ -0,0 +1,109 @@
+import { useState } from "react";
+import dgram from "react-native-udp";
+
+const JELLYFIN_DISCOVERY_PORT = 7359;
+const DISCOVERY_MESSAGE = "Who is JellyfinServer?";
+
+interface ServerInfo {
+  address: string;
+  port: number;
+  serverId?: string;
+  serverName?: string;
+}
+
+const stringToUint8Array = (str: string): Uint8Array => {
+  const arr = new Uint8Array(str.length);
+  for (let i = 0; i < str.length; i++) {
+    arr[i] = str.charCodeAt(i);
+  }
+  return arr;
+};
+
+export const useJellyfinDiscovery = () => {
+  const [servers, setServers] = useState<ServerInfo[]>([]);
+  const [isSearching, setIsSearching] = useState(false);
+
+  const startDiscovery = () => {
+    setIsSearching(true);
+    setServers([]);
+
+    const discoveredServers = new Set<string>();
+
+    const socket = dgram.createSocket({
+      type: "udp4",
+      reusePort: true,
+      debug: __DEV__,
+    });
+
+    socket.on("error", (err) => {
+      console.error("Socket error:", err);
+      socket.close();
+      setIsSearching(false);
+    });
+
+    socket.bind(0, () => {
+      console.log("UDP socket bound successfully");
+
+      try {
+        socket.setBroadcast(true);
+        const messageBuffer = stringToUint8Array(DISCOVERY_MESSAGE);
+
+        socket.send(
+          messageBuffer,
+          0,
+          messageBuffer.length,
+          JELLYFIN_DISCOVERY_PORT,
+          "255.255.255.255",
+          (err) => {
+            if (err) {
+              console.error("Failed to send discovery message:", err);
+              return;
+            }
+            console.log("Discovery message sent successfully");
+          }
+        );
+
+        setTimeout(() => {
+          setIsSearching(false);
+          socket.close();
+        }, 5000);
+      } catch (error) {
+        console.error("Error during discovery:", error);
+        setIsSearching(false);
+      }
+    });
+
+    socket.on("message", (msg, rinfo: any) => {
+      if (discoveredServers.has(rinfo.address)) {
+        return;
+      }
+
+      try {
+        const response = String.fromCharCode(...new Uint8Array(msg));
+        const serverInfo = JSON.parse(response);
+        discoveredServers.add(rinfo.address);
+
+        const newServer: ServerInfo = {
+          address: `http://${rinfo.address}:${serverInfo.Port || 8096}`,
+          port: serverInfo.Port || 8096,
+          serverId: serverInfo.Id,
+          serverName: serverInfo.Name,
+        };
+
+        setServers((prev) => [...prev, newServer]);
+      } catch (error) {
+        console.error("Error parsing server response:", error);
+      }
+    });
+
+    return () => {
+      socket.close();
+    };
+  };
+
+  return {
+    servers,
+    isSearching,
+    startDiscovery,
+  };
+};