fix(vercel): now works with monorepos (#5033)

* Upgraded nft

* Handle monorepo better

* Changeset

* Fixed common ancestor

* Fixed outdir

1 files changed, 68 insertions, 16 deletions

diff --git a/packages/integrations/vercel/src/lib/nft.ts b/packages/integrations/vercel/src/lib/nft.ts
index b18cb73ef..ba3677583 100644
--- a/packages/integrations/vercel/src/lib/nft.ts
+++ b/packages/integrations/vercel/src/lib/nft.ts
@@ -1,38 +1,90 @@
 import { nodeFileTrace } from '@vercel/nft';
 import * as fs from 'node:fs/promises';
+import nodePath from 'node:path';
 import { fileURLToPath } from 'node:url';
 
 export async function copyDependenciesToFunction(
-	root: URL,
-	functionFolder: URL,
-	serverEntry: string
-) {
-	const entryPath = fileURLToPath(new URL(`./${serverEntry}`, functionFolder));
+	entry: URL,
+	outDir: URL
+): Promise<{ handler: string }> {
+	const entryPath = fileURLToPath(entry);
+
+	// Get root of folder of the system (like C:\ on Windows or / on Linux)
+	let base = entry;
+	while (fileURLToPath(base) !== fileURLToPath(new URL('../', base))) {
+		base = new URL('../', base);
+	}
 
 	const result = await nodeFileTrace([entryPath], {
-		base: fileURLToPath(root),
+		base: fileURLToPath(base),
 	});
 
-	for (const file of result.fileList) {
-		if (file.startsWith('.vercel/')) continue;
-		const origin = new URL(file, root);
-		const dest = new URL(file, functionFolder);
+	if (result.fileList.size === 0) throw new Error('[@astrojs/vercel] No files found');
+
+	for (const error of result.warnings) {
+		if (error.message.startsWith('Failed to resolve dependency')) {
+			const [, module, file] = /Cannot find module '(.+?)' loaded from (.+)/.exec(error.message)!;
+
+			// The import(astroRemark) sometimes fails to resolve, but it's not a problem
+			if (module === '@astrojs/') continue;
+
+			if (entryPath === file) {
+				console.warn(
+					`[@astrojs/vercel] The module "${module}" couldn't be resolved. This may not be a problem, but it's worth checking.`
+				);
+			} else {
+				console.warn(
+					`[@astrojs/vercel] The module "${module}" inside the file "${file}" couldn't be resolved. This may not be a problem, but it's worth checking.`
+				);
+			}
+		} else {
+			throw error;
+		}
+	}
 
-		const meta = await fs.stat(origin);
-		const isSymlink = (await fs.lstat(origin)).isSymbolicLink();
+	const fileList = [...result.fileList];
+
+	let commonAncestor = nodePath.dirname(fileList[0]);
+	for (const file of fileList.slice(1)) {
+		while (!file.startsWith(commonAncestor)) {
+			commonAncestor = nodePath.dirname(commonAncestor);
+		}
+	}
+
+	for (const file of fileList) {
+		const origin = new URL(file, base);
+		const dest = new URL(nodePath.relative(commonAncestor, file), outDir);
+
+		const realpath = await fs.realpath(origin);
+		const isSymlink = realpath !== fileURLToPath(origin);
+		const isDir = (await fs.stat(origin)).isDirectory();
 
 		// Create directories recursively
-		if (meta.isDirectory() && !isSymlink) {
+		if (isDir && !isSymlink) {
 			await fs.mkdir(new URL('..', dest), { recursive: true });
 		} else {
 			await fs.mkdir(new URL('.', dest), { recursive: true });
 		}
 
 		if (isSymlink) {
-			const link = await fs.readlink(origin);
-			await fs.symlink(link, dest, meta.isDirectory() ? 'dir' : 'file');
-		} else {
+			const realdest = fileURLToPath(
+				new URL(
+					nodePath.relative(nodePath.join(fileURLToPath(base), commonAncestor), realpath),
+					outDir
+				)
+			);
+			await fs.symlink(
+				nodePath.relative(fileURLToPath(new URL('.', dest)), realdest),
+				dest,
+				isDir ? 'dir' : 'file'
+			);
+		} else if (!isDir) {
 			await fs.copyFile(origin, dest);
 		}
 	}
+
+	return {
+		// serverEntry location inside the outDir
+		handler: nodePath.relative(nodePath.join(fileURLToPath(base), commonAncestor), entryPath),
+	};
 }