Instance Detector 추가

src/server/utils/detectInstance.ts

@@ -0,0 +1,36 @@
+import fetch from 'node-fetch';
+
+type nodeinfoMeta =
+{
+	links: nodeinfoVersionList[];
+};
+
+type nodeinfoVersionList = 
+{
+	rel: string;
+	href: string;
+}
+
+type nodeinfo = 
+{
+	version: string;
+	software: { name: string; version: string };
+	// irrelevent properties skipped
+}
+
+export default async function detectInstance(url: string): Promise<string|undefined>
+{
+	const parsedURL = new URL(url);
+	if(parsedURL.hostname === 'twitter.com')
+		return 'twitter';
+	
+	// fediverse
+	const nodeinfoMeta: nodeinfoMeta = await fetch(`${parsedURL.origin}/.well-known/nodeinfo`).then(r => r.json());
+	const nodeinfoLink = nodeinfoMeta.links.find(elem => elem.rel === 'http://nodeinfo.diaspora.software/ns/schema/2.0');
+
+	// TODO: add support for 1.0 as a fallback? All latest versions of major AP softwares seem to support 2.0 tho
+	if(!nodeinfoLink)
+		return undefined;
+	const nodeinfo: nodeinfo = await fetch(`${nodeinfoLink.href}`).then(r => r.json());
+	return nodeinfo.software.name;
+}