1 files changed, 124 insertions, 0 deletions
diff --git a/packages/integrations/vercel/src/serverless/middleware.ts b/packages/integrations/vercel/src/serverless/middleware.ts
new file mode 100644
index 000000000..07d0843bf
--- /dev/null
+++ b/packages/integrations/vercel/src/serverless/middleware.ts
@@ -0,0 +1,124 @@
+import { existsSync } from 'node:fs';
+import { builtinModules } from 'node:module';
+import { fileURLToPath, pathToFileURL } from 'node:url';
+import type { AstroIntegrationLogger } from 'astro';
+import {
+	ASTRO_LOCALS_HEADER,
+	ASTRO_MIDDLEWARE_SECRET_HEADER,
+	ASTRO_PATH_HEADER,
+	NODE_PATH,
+} from './adapter.js';
+
+/**
+ * It generates the Vercel Edge Middleware file.
+ *
+ * It creates a temporary file, the edge middleware, with some dynamic info.
+ *
+ * Then this file gets bundled with esbuild. The bundle phase will inline the Astro middleware code.
+ *
+ * @param astroMiddlewareEntryPoint
+ * @param outPath
+ * @returns {Promise<URL>} The path to the bundled file
+ */
+export async function generateEdgeMiddleware(
+	astroMiddlewareEntryPointPath: URL,
+	root: URL,
+	vercelEdgeMiddlewareHandlerPath: URL,
+	outPath: URL,
+	middlewareSecret: string,
+	logger: AstroIntegrationLogger,
+): Promise<URL> {
+	const code = edgeMiddlewareTemplate(
+		astroMiddlewareEntryPointPath,
+		vercelEdgeMiddlewareHandlerPath,
+		middlewareSecret,
+		logger,
+	);
+	// https://vercel.com/docs/concepts/functions/edge-middleware#create-edge-middleware
+	const bundledFilePath = fileURLToPath(outPath);
+	const esbuild = await import('esbuild');
+	await esbuild.build({
+		stdin: {
+			contents: code,
+			resolveDir: fileURLToPath(root),
+		},
+		target: 'es2020',
+		platform: 'browser',
+		// https://runtime-keys.proposal.wintercg.org/#edge-light
+		conditions: ['edge-light', 'worker', 'browser'],
+		outfile: bundledFilePath,
+		allowOverwrite: true,
+		format: 'esm',
+		bundle: true,
+		minify: false,
+		// ensure node built-in modules are namespaced with `node:`
+		plugins: [
+			{
+				name: 'esbuild-namespace-node-built-in-modules',
+				setup(build) {
+					const filter = new RegExp(builtinModules.map((mod) => `(^${mod}$)`).join('|'));
+					build.onResolve({ filter }, (args) => ({ path: 'node:' + args.path, external: true }));
+				},
+			},
+		],
+	});
+	return pathToFileURL(bundledFilePath);
+}
+
+function edgeMiddlewareTemplate(
+	astroMiddlewareEntryPointPath: URL,
+	vercelEdgeMiddlewareHandlerPath: URL,
+	middlewareSecret: string,
+	logger: AstroIntegrationLogger,
+) {
+	const middlewarePath = JSON.stringify(
+		fileURLToPath(astroMiddlewareEntryPointPath).replace(/\\/g, '/'),
+	);
+	const filePathEdgeMiddleware = fileURLToPath(vercelEdgeMiddlewareHandlerPath);
+	let handlerTemplateImport = '';
+	let handlerTemplateCall = '{}';
+	if (existsSync(filePathEdgeMiddleware + '.js') || existsSync(filePathEdgeMiddleware + '.ts')) {
+		logger.warn(
+			'Usage of `vercel-edge-middleware.js` is deprecated. You can now use the `waitUntil(promise)` function directly as `ctx.locals.waitUntil(promise)`.',
+		);
+		const stringified = JSON.stringify(filePathEdgeMiddleware.replace(/\\/g, '/'));
+		handlerTemplateImport = `import handler from ${stringified}`;
+		handlerTemplateCall = `await handler({ request, context })`;
+	} else {
+	}
+	return `
+	${handlerTemplateImport}
+import { onRequest } from ${middlewarePath};
+import { createContext, trySerializeLocals } from 'astro/middleware';
+export default async function middleware(request, context) {
+	const ctx = createContext({
+		request,
+		params: {}
+	});
+	ctx.locals = { vercel: { edge: context }, ...${handlerTemplateCall} };
+	const { origin } = new URL(request.url);
+	const next = async () => {
+		const { vercel, ...locals } = ctx.locals;
+		const response = await fetch(new URL('/${NODE_PATH}', request.url), {
+			headers: {
+				...Object.fromEntries(request.headers.entries()),
+				'${ASTRO_MIDDLEWARE_SECRET_HEADER}': '${middlewareSecret}',
+				'${ASTRO_PATH_HEADER}': request.url.replace(origin, ''),
+				'${ASTRO_LOCALS_HEADER}': trySerializeLocals(locals)
+			}
+		});
+		return new Response(response.body, {
+			status: response.status,
+			statusText: response.statusText,
+			headers: response.headers,
+		});
+	};
+
+	const response = await onRequest(ctx, next);
+	// Append cookies from Astro.cookies
+	for(const setCookieHeaderValue of ctx.cookies.headers()) {
+		response.headers.append('set-cookie', setCookieHeaderValue);
+	}
+	return response;
+}`;
+}