feat: Switch to direct download of vnu.jar (rather than npm package)

src/validate-input-markup.ts

@@ -1,5 +1,6 @@
 import { createRequire } from "node:module";
 import { env, exit, install, sh, yesOrNo } from "./utils.ts";
+import { ensureVnuJar } from "./vnu-jar-download.ts";
 
 import type { ProcessedInput } from "./prepare.ts";
 type Input = Pick<ProcessedInput["build"], "source">;
@@ -17,8 +18,11 @@ if (import.meta.main) {
 
 export default async function main({ source }: Input) {
 	console.log(`Validating ${source}...`);
-	await install("vnu-jar");
-	const vnuJar = require("vnu-jar");
+	const vnuJar = await ensureVnuJar({
+		log: console.log,
+		maxRetries: 5,
+		retryDelayMs: 500,
+	});
 
 	try {
 		await sh(`java -jar "${vnuJar}" ${source}`, {

src/validate-markup.ts

@@ -1,5 +1,6 @@
 import { createRequire } from "node:module";
 import { env, exit, install, sh, yesOrNo } from "./utils.ts";
+import { ensureVnuJar } from "./vnu-jar-download.ts";
 
 import type { BuildResult } from "./build.ts";
 type Input = Pick<BuildResult, "dest" | "file">;
@@ -17,8 +18,11 @@ if (import.meta.main) {
 
 export default async function main({ dest, file }: Input) {
 	console.log(`Validating ${file}...`);
-	await install("vnu-jar");
-	const vnuJar = require("vnu-jar");
+	const vnuJar = await ensureVnuJar({
+		log: console.log,
+		maxRetries: 5,
+		retryDelayMs: 500,
+	});
 
 	try {
 		await sh(`java -jar "${vnuJar}" --also-check-css ${file}`, {

src/vnu-jar-download.ts

@@ -0,0 +1,158 @@
+import fs from "node:fs/promises";
+import fsSync from "node:fs";
+import path from "node:path";
+import os from "node:os";
+import https from "node:https";
+import { IncomingMessage, ClientRequest } from "node:http";
+import crypto from "node:crypto";
+
+const BASE_URL =
+	"https://github.com/validator/validator/releases/download/latest";
+const JAR_URL = `${BASE_URL}/vnu.jar`;
+const SHA1_URL = `${BASE_URL}/vnu.jar.sha1`;
+
+export interface DownloadOptions {
+	log?: (msg: string) => void;
+	maxRetries?: number;
+	retryDelayMs?: number;
+}
+
+function getCacheDir(): string {
+	const platform = os.platform();
+	let root: string;
+	if (platform === "win32") {
+		root =
+			process.env.LOCALAPPDATA || path.join(os.homedir(), "AppData", "Local");
+	} else if (platform === "darwin") {
+		root = path.join(os.homedir(), "Library", "Caches");
+	} else {
+		root = process.env.XDG_CACHE_HOME || path.join(os.homedir(), ".cache");
+	}
+	return path.join(root, "vnu", "latest");
+}
+
+async function sha1OfFile(file: string): Promise<string> {
+	return new Promise((resolve, reject) => {
+		const hash = crypto.createHash("sha1");
+		const stream = fsSync.createReadStream(file);
+		stream.on("data", (chunk: Buffer | string) => {
+			hash.update(chunk as Buffer);
+		});
+		stream.on("end", () => resolve(hash.digest("hex")));
+		stream.on("error", reject);
+	});
+}
+
+async function downloadWithRetry(
+	url: string,
+	dest: string,
+	headers?: Record<string, string>,
+	options: DownloadOptions = {},
+): Promise<IncomingMessage> {
+	const { maxRetries = 3, retryDelayMs = 500 } = options;
+	for (let attempt = 0; attempt <= maxRetries; attempt++) {
+		try {
+			await fs.mkdir(path.dirname(dest), { recursive: true });
+			return await new Promise<IncomingMessage>((resolve, reject) => {
+				const file = fsSync.createWriteStream(dest);
+				const req: ClientRequest = https.get(
+					url,
+					{ headers },
+					(res: IncomingMessage) => {
+						if (res.statusCode && res.statusCode >= 400) {
+							reject(
+								new Error(
+									`Download failed: ${res.statusCode} ${res.statusMessage}`,
+								),
+							);
+							return;
+						}
+						if (res.statusCode === 304) {
+							file.close();
+							resolve(res);
+							return;
+						}
+						res.pipe(file);
+						file.on("finish", () => file.close(() => resolve(res)));
+						file.on("error", reject);
+					},
+				);
+				req.on("error", reject);
+			});
+		} catch (err) {
+			if (attempt < maxRetries) {
+				const delay = retryDelayMs * 2 ** attempt;
+				await new Promise(res => setTimeout(res, delay));
+			} else {
+				throw err;
+			}
+		}
+	}
+	throw new Error("Unreachable code in downloadWithRetry");
+}
+
+export async function ensureVnuJar(
+	options: DownloadOptions = {},
+): Promise<string> {
+	const { log = () => {}, maxRetries = 3, retryDelayMs = 500 } = options;
+	const cacheDir = getCacheDir();
+	const jarPath = path.join(cacheDir, "vnu.jar");
+	const shaPath = path.join(cacheDir, "vnu.jar.sha1");
+	const metaPath = path.join(cacheDir, "vnu.meta.json");
+	let expectedSha: string | null = null;
+	let etag: string | undefined;
+	let lastModified: string | undefined;
+	try {
+		const meta = JSON.parse(await fs.readFile(metaPath, "utf8")) as {
+			etag?: string;
+			lastModified?: string;
+			sha?: string;
+		};
+		etag = meta.etag;
+		lastModified = meta.lastModified;
+		expectedSha = meta.sha ?? null;
+		if (expectedSha && fsSync.existsSync(jarPath)) {
+			const actualSha = await sha1OfFile(jarPath);
+			if (actualSha === expectedSha) {
+				log("✅ vnu.jar cache hit and valid");
+				return jarPath;
+			}
+			log("⚠️ Cached vnu.jar checksum mismatch, redownloading...");
+		}
+	} catch {}
+	const shaHeaders: Record<string, string> = {};
+	if (etag) shaHeaders["If-None-Match"] = etag;
+	if (lastModified) shaHeaders["If-Modified-Since"] = lastModified;
+	await downloadWithRetry(SHA1_URL, shaPath, shaHeaders, {
+		maxRetries,
+		retryDelayMs,
+	});
+	expectedSha = (await fs.readFile(shaPath, "utf8")).trim();
+	log("⬇️ Downloading vnu.jar...");
+	const res = await downloadWithRetry(
+		JAR_URL,
+		jarPath,
+		{},
+		{ maxRetries, retryDelayMs },
+	);
+	const newEtag = res.headers.etag;
+	const newLastModified = res.headers["last-modified"];
+	await fs.writeFile(
+		metaPath,
+		JSON.stringify(
+			{ etag: newEtag, lastModified: newLastModified, sha: expectedSha },
+			null,
+			2,
+		),
+		"utf8",
+	);
+	const actualSha = await sha1OfFile(jarPath);
+	if (actualSha !== expectedSha) {
+		await fs.unlink(jarPath).catch(() => {});
+		throw new Error(
+			`Checksum mismatch for vnu.jar: expected ${expectedSha}, got ${actualSha}`,
+		);
+	}
+	log("✅ vnu.jar ready");
+	return jarPath;
+}