feat(node): add trailingSlash support (#9080)

* feat(node): add trailing slash support

* add changeset

* test(node): add base route test in trailing-slash.js

detected an infinite loop in base path when trailingSlash: never

* fix(node): avoid infinite redirect when trailingSlash: never

* address test failures after rebase pt.1

* address test failures after rebase pt.2

---------

Co-authored-by: lilnasy <69170106+lilnasy@users.noreply.github.com>

3 files changed, 49 insertions, 16 deletions

diff --git a/packages/integrations/node/src/serve-static.ts b/packages/integrations/node/src/serve-static.ts
index 77de9b358..a88b1332f 100644
--- a/packages/integrations/node/src/serve-static.ts
+++ b/packages/integrations/node/src/serve-static.ts
@@ -1,5 +1,6 @@
 import path from 'node:path';
 import url from 'node:url';
+import fs from 'node:fs';
 import send from 'send';
 import type { IncomingMessage, ServerResponse } from 'node:http';
 import type { Options } from './types.js';
@@ -18,8 +19,47 @@ export function createStaticHandler(app: NodeApp, options: Options) {
 	 */
 	return (req: IncomingMessage, res: ServerResponse, ssr: () => unknown) => {
 		if (req.url) {
-			let pathname = app.removeBase(req.url);
-			pathname = decodeURI(new URL(pathname, 'http://host').pathname);
+			const [urlPath, urlQuery] = req.url.split('?');
+			const filePath = path.join(client, app.removeBase(urlPath));
+
+			let pathname: string;
+			let isDirectory = false;
+			try {
+				isDirectory = fs.lstatSync(filePath).isDirectory();
+			} catch {}
+
+			const { trailingSlash = 'ignore' } = options;
+
+			const hasSlash = urlPath.endsWith('/');
+			switch (trailingSlash) {
+				case "never":
+					if (isDirectory && (urlPath != '/') && hasSlash) {
+						pathname = urlPath.slice(0, -1) + (urlQuery ? "?" + urlQuery : "");
+						res.statusCode = 301;
+						res.setHeader('Location', pathname);
+						return res.end();
+					} else pathname = urlPath;
+					// intentionally fall through
+				case "ignore":
+					{
+						if (isDirectory && !hasSlash) {
+							pathname = urlPath + "/index.html";
+						} else
+							pathname = urlPath;
+					}
+					break;
+				case "always":
+					if (!hasSlash) {
+						pathname = urlPath + '/' +(urlQuery ? "?" + urlQuery : "");
+						res.statusCode = 301;
+						res.setHeader('Location', pathname);
+						return res.end();
+					} else
+						pathname = urlPath;
+				break;
+			}
+			// app.removeBase sometimes returns a path without a leading slash
+			pathname = prependForwardSlash(app.removeBase(pathname));
 
 			const stream = send(req, pathname, {
 				root: client,
@@ -47,20 +87,6 @@ export function createStaticHandler(app: NodeApp, options: Options) {
 					_res.setHeader('Cache-Control', 'public, max-age=31536000, immutable');
 				}
 			});
-			stream.on('directory', () => {
-				// On directory find, redirect to the trailing slash
-				let location: string;
-				if (req.url!.includes('?')) {
-					const [url1 = '', search] = req.url!.split('?');
-					location = `${url1}/?${search}`;
-				} else {
-					location = appendForwardSlash(req.url!);
-				}
-
-				res.statusCode = 301;
-				res.setHeader('Location', location);
-				res.end(location);
-			});
 			stream.on('file', () => {
 				forwardError = true;
 			});
@@ -81,6 +107,10 @@ function resolveClientDir(options: Options) {
 	return client;
 }
 
+function prependForwardSlash(pth: string) {
+	return pth.startsWith('/') ? pth : '/' + pth;
+}
+
 function appendForwardSlash(pth: string) {
 	return pth.endsWith('/') ? pth : pth + '/';
 }
diff --git a/packages/integrations/node/src/server.ts b/packages/integrations/node/src/server.ts
index d9f24cca5..73b59c53f 100644
--- a/packages/integrations/node/src/server.ts
+++ b/packages/integrations/node/src/server.ts
@@ -8,6 +8,7 @@ import type { Options } from './types.js';
 applyPolyfills();
 export function createExports(manifest: SSRManifest, options: Options) {
 	const app = new NodeApp(manifest);
+	options.trailingSlash = manifest.trailingSlash;
 	return {
 		options: options,
 		handler:
diff --git a/packages/integrations/node/src/types.ts b/packages/integrations/node/src/types.ts
index 9e4f4ce91..3c03dffac 100644
--- a/packages/integrations/node/src/types.ts
+++ b/packages/integrations/node/src/types.ts
@@ -1,5 +1,6 @@
 import type { NodeApp } from 'astro/app/node';
 import type { IncomingMessage, ServerResponse } from 'node:http';
+import type { SSRManifest } from 'astro';
 
 export interface UserOptions {
 	/**
@@ -17,6 +18,7 @@ export interface Options extends UserOptions {
 	server: string;
 	client: string;
 	assets: string;
+	trailingSlash?: SSRManifest['trailingSlash'];
 }
 
 export interface CreateServerOptions {