add lazyload and move readme to func, add cache for readme and css

src/routes/api/readme.ts

@@ -1,5 +1,8 @@
+import { redisTtl } from "@config/environment";
 import { fetch } from "bun";
+import { redis } from "bun";
 import DOMPurify from "isomorphic-dompurify";
+import { parseHTML } from "linkedom";
 import { marked } from "marked";
 
 const routeDef: RouteDef = {
@@ -9,6 +12,50 @@ const routeDef: RouteDef = {
 	log: false,
 };
 
+async function fetchAndCacheReadme(url: string): Promise<string | null> {
+	const cacheKey = `readme:${url}`;
+	const cached = await redis.get(cacheKey);
+	if (cached) return cached;
+
+	const res = await fetch(url, {
+		headers: {
+			Accept: "text/markdown",
+		},
+	});
+
+	if (!res.ok) return null;
+
+	if (res.headers.has("content-length")) {
+		const size = Number.parseInt(res.headers.get("content-length") || "0", 10);
+		if (size > 1024 * 100) return null;
+	}
+
+	const text = await res.text();
+	if (!text || text.length < 10) return null;
+
+	let html: string;
+	if (/\.(html?|htm)$/i.test(url)) {
+		html = text;
+	} else {
+		html = await marked.parse(text);
+	}
+
+	const { document } = parseHTML(html);
+	for (const img of Array.from(document.querySelectorAll("img"))) {
+		if (!img.hasAttribute("loading")) {
+			img.setAttribute("loading", "lazy");
+		}
+	}
+
+	const dirtyHtml = document.toString();
+	const safe = DOMPurify.sanitize(dirtyHtml) || "";
+
+	await redis.set(cacheKey, safe);
+	await redis.expire(cacheKey, redisTtl);
+
+	return safe;
+}
+
 async function handler(request: ExtendedRequest): Promise<Response> {
 	const { url } = request.query;
 
@@ -29,68 +76,21 @@ async function handler(request: ExtendedRequest): Promise<Response> {
 		);
 	}
 
-	const res = await fetch(url, {
-		headers: {
-			Accept: "text/markdown",
-		},
-	});
+	const safe = await fetchAndCacheReadme(url);
 
-	if (!res.ok) {
+	if (!safe) {
 		return Response.json(
 			{
 				success: false,
 				error: {
 					code: "FETCH_FAILED",
-					message: "Failed to fetch the file",
+					message: "Failed to fetch or process file",
 				},
 			},
 			{ status: 400 },
 		);
 	}
 
-	if (res.headers.has("content-length")) {
-		const size = Number.parseInt(res.headers.get("content-length") || "0", 10);
-		if (size > 1024 * 100) {
-			return Response.json(
-				{
-					success: false,
-					error: {
-						code: "FILE_TOO_LARGE",
-						message: "File size exceeds 100KB limit",
-					},
-				},
-				{ status: 400 },
-			);
-		}
-	}
-
-	const text = await res.text();
-	if (!text || text.length < 10) {
-		return Response.json(
-			{
-				success: false,
-				error: {
-					code: "INVALID_CONTENT",
-					message: "File is too small or invalid",
-				},
-			},
-			{ status: 400 },
-		);
-	}
-
-	let html: string;
-
-	if (
-		url.toLowerCase().endsWith(".html") ||
-		url.toLowerCase().endsWith(".htm")
-	) {
-		html = text;
-	} else {
-		html = await marked.parse(text);
-	}
-
-	const safe = DOMPurify.sanitize(html) || "";
-
 	return new Response(safe, {
 		headers: {
 			"Content-Type": "text/html; charset=utf-8",