feature(astrojs/cloudflare): add support for `splitted` SSR bundles (#7464)

* initial commit

* try to fix windows

* output files directly into the correct folder

* allow for rest parameters

* use fixed hook

* improve tests

* apply doc's team suggestions for README

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

* try to fix prerendering

* apply doc's team suggestion for changeset

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

* bump to minor

* readme update

* resolve review comments

* optimize memory allocation

* resolve review comments

* add removed link, to make sure old docs keep same

* resolve comment

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

---------

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>
Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

16 files changed, 338 insertions, 46 deletions

diff --git a/.changeset/healthy-books-study.md b/.changeset/healthy-books-study.md
new file mode 100644
index 000000000..e4b51b041
--- /dev/null
+++ b/.changeset/healthy-books-study.md
@@ -0,0 +1,7 @@
+---
+'@astrojs/cloudflare': minor
+---
+
+Split Support in Cloudflare
+
+Adds support for configuring `build.split` when using the Cloudflare adapter
diff --git a/packages/integrations/cloudflare/README.md b/packages/integrations/cloudflare/README.md
index 6f69e3bdd..a6638f36d 100644
--- a/packages/integrations/cloudflare/README.md
+++ b/packages/integrations/cloudflare/README.md
@@ -48,7 +48,11 @@ Cloudflare Pages has 2 different modes for deploying functions, `advanced` mode
 
 For most projects the adapter default of `advanced` will be sufficient; the `dist` folder will contain your compiled project. Switching to directory mode allows you to use [pages plugins](https://developers.cloudflare.com/pages/platform/functions/plugins/) such as [Sentry](https://developers.cloudflare.com/pages/platform/functions/plugins/sentry/) or write custom code to enable logging.
 
-In directory mode the adapter will compile the client side part of your app the same way, but moves the worker script into a `functions` folder in the project root. The adapter will only ever place a `[[path]].js` in that folder, allowing you to add additional plugins and pages middleware which can be checked into version control. Cloudflare documentation contains more information about [writing custom functions](https://developers.cloudflare.com/pages/platform/functions/).
+In directory mode, the adapter will compile the client side part of your app the same way by default, but moves the worker script into a `functions` folder in the project root. In this case, the adapter will only ever place a `[[path]].js` in that folder, allowing you to add additional plugins and pages middleware which can be checked into version control.
+
+With the build configuration `split: true`, the adapter instead compiles a separate bundle for each page. This option requires some manual maintenance of the `functions` folder. Files emitted by Astro will overwrite existing `functions` files with identical names, so you must choose unique file names for each file you manually add. Additionally, the adapter will never empty the `functions` folder of outdated files, so you must clean up the folder manually when you remove pages.
+
+Note that this adapter does not support using [Cloudflare Pages Middleware](https://developers.cloudflare.com/pages/platform/functions/middleware/). Astro will bundle the [Astro middleware](https://docs.astro.build/en/guides/middleware/) into each page.
 
 ```ts
 // directory mode
diff --git a/packages/integrations/cloudflare/package.json b/packages/integrations/cloudflare/package.json
index fe64ee166..f4ad834a0 100644
--- a/packages/integrations/cloudflare/package.json
+++ b/packages/integrations/cloudflare/package.json
@@ -35,7 +35,8 @@
     "build": "astro-scripts build \"src/**/*.ts\" && tsc",
     "build:ci": "astro-scripts build \"src/**/*.ts\"",
     "dev": "astro-scripts dev \"src/**/*.ts\"",
-    "test": "mocha --exit --timeout 30000 test/"
+    "test": "mocha --exit --timeout 30000 test/",
+    "test:match": "mocha --exit --timeout 30000 -g"
   },
   "dependencies": {
     "@astrojs/underscore-redirects": "^0.1.0",
diff --git a/packages/integrations/cloudflare/src/index.ts b/packages/integrations/cloudflare/src/index.ts
index 252dd778a..f4ee26fea 100644
--- a/packages/integrations/cloudflare/src/index.ts
+++ b/packages/integrations/cloudflare/src/index.ts
@@ -1,8 +1,9 @@
 import { createRedirectsFromAstroRoutes } from '@astrojs/underscore-redirects';
-import type { AstroAdapter, AstroConfig, AstroIntegration } from 'astro';
+import type { AstroAdapter, AstroConfig, AstroIntegration, RouteData } from 'astro';
 import esbuild from 'esbuild';
 import * as fs from 'fs';
 import * as os from 'os';
+import { dirname } from 'path';
 import glob from 'tiny-glob';
 import { fileURLToPath, pathToFileURL } from 'url';
 
@@ -14,20 +15,21 @@ interface BuildConfig {
 	server: URL;
 	client: URL;
 	serverEntry: string;
+	split?: boolean;
 }
 
 export function getAdapter(isModeDirectory: boolean): AstroAdapter {
 	return isModeDirectory
 		? {
-				name: '@astrojs/cloudflare',
-				serverEntrypoint: '@astrojs/cloudflare/server.directory.js',
-				exports: ['onRequest'],
-		  }
+			name: '@astrojs/cloudflare',
+			serverEntrypoint: '@astrojs/cloudflare/server.directory.js',
+			exports: ['onRequest', 'manifest'],
+		}
 		: {
-				name: '@astrojs/cloudflare',
-				serverEntrypoint: '@astrojs/cloudflare/server.advanced.js',
-				exports: ['default'],
-		  };
+			name: '@astrojs/cloudflare',
+			serverEntrypoint: '@astrojs/cloudflare/server.advanced.js',
+			exports: ['default'],
+		};
 }
 
 const SHIM = `globalThis.process = {
@@ -41,6 +43,7 @@ export default function createIntegration(args?: Options): AstroIntegration {
 	let _config: AstroConfig;
 	let _buildConfig: BuildConfig;
 	const isModeDirectory = args?.mode === 'directory';
+	let _entryPoints = new Map<RouteData, URL>();
 
 	return {
 		name: '@astrojs/cloudflare',
@@ -90,35 +93,99 @@ export default function createIntegration(args?: Options): AstroIntegration {
 					vite.ssr.target = 'webworker';
 				}
 			},
+			'astro:build:ssr': ({ manifest, entryPoints }) => {
+				_entryPoints = entryPoints;
+			},
 			'astro:build:done': async ({ pages, routes, dir }) => {
-				const entryPath = fileURLToPath(new URL(_buildConfig.serverEntry, _buildConfig.server));
-				const entryUrl = new URL(_buildConfig.serverEntry, _config.outDir);
-				const buildPath = fileURLToPath(entryUrl);
-				// A URL for the final build path after renaming
-				const finalBuildUrl = pathToFileURL(buildPath.replace(/\.mjs$/, '.js'));
-
-				await esbuild.build({
-					target: 'es2020',
-					platform: 'browser',
-					conditions: ['workerd', 'worker', 'browser'],
-					entryPoints: [entryPath],
-					outfile: buildPath,
-					allowOverwrite: true,
-					format: 'esm',
-					bundle: true,
-					minify: _config.vite?.build?.minify !== false,
-					banner: {
-						js: SHIM,
-					},
-					logOverride: {
-						'ignored-bare-import': 'silent',
-					},
-				});
+				const functionsUrl = new URL('functions/', _config.root);
+
+				if (isModeDirectory) {
+					await fs.promises.mkdir(functionsUrl, { recursive: true });
+				}
+
+				if (isModeDirectory && _buildConfig.split) {
+					const entryPointsRouteData = [..._entryPoints.keys()]
+					const entryPointsURL = [..._entryPoints.values()]
+					const entryPaths = entryPointsURL.map((entry) => fileURLToPath(entry));
+					const outputDir = fileURLToPath(new URL('.astro', _buildConfig.server));
+
+					// NOTE: AFAIK, esbuild keeps the order of the entryPoints array
+					const { outputFiles } = await esbuild.build({
+						target: 'es2020',
+						platform: 'browser',
+						conditions: ['workerd', 'worker', 'browser'],
+						entryPoints: entryPaths,
+						outdir: outputDir,
+						allowOverwrite: true,
+						format: 'esm',
+						bundle: true,
+						minify: _config.vite?.build?.minify !== false,
+						banner: {
+							js: SHIM,
+						},
+						logOverride: {
+							'ignored-bare-import': 'silent',
+						},
+						write: false,
+					});
 
-				// Rename to worker.js
-				await fs.promises.rename(buildPath, finalBuildUrl);
+					// loop through all bundled files and write them to the functions folder
+					for (const [index, outputFile] of outputFiles.entries()) {
+						// we need to make sure the filename in the functions folder
+						// matches to cloudflares routing capabilities (see their docs)
+						// IN: src/pages/[language]/files/[...path].astro
+						// OUT: [language]/files/[[path]].js
+						const fileName = entryPointsRouteData[index].component
+							.replace('src/pages/', '')
+							.replace('.astro', '.js')
+							.replace(/(\[\.\.\.)(\w+)(\])/g, (_match, _p1, p2, _p3) => {
+								return `[[${p2}]]`;
+							});
+
+						const fileUrl = new URL(fileName, functionsUrl)
+						const newFileDir = dirname(fileURLToPath(fileUrl));
+						if (!fs.existsSync(newFileDir)) {
+							fs.mkdirSync(newFileDir, { recursive: true });
+						}
+						await fs.promises.writeFile(fileUrl, outputFile.contents);
+					}
 
-				// throw the server folder in the bin
+				} else {
+					const entryPath = fileURLToPath(new URL(_buildConfig.serverEntry, _buildConfig.server));
+					const entryUrl = new URL(_buildConfig.serverEntry, _config.outDir);
+					const buildPath = fileURLToPath(entryUrl);
+					// A URL for the final build path after renaming
+					const finalBuildUrl = pathToFileURL(buildPath.replace(/\.mjs$/, '.js'));
+
+					await esbuild.build({
+						target: 'es2020',
+						platform: 'browser',
+						conditions: ['workerd', 'worker', 'browser'],
+						entryPoints: [entryPath],
+						outfile: buildPath,
+						allowOverwrite: true,
+						format: 'esm',
+						bundle: true,
+						minify: _config.vite?.build?.minify !== false,
+						banner: {
+							js: SHIM,
+						},
+						logOverride: {
+							'ignored-bare-import': 'silent',
+						},
+					});
+
+					// Rename to worker.js
+					await fs.promises.rename(buildPath, finalBuildUrl);
+
+					if (isModeDirectory) {
+						const directoryUrl = new URL('[[path]].js', functionsUrl);
+						await fs.promises.rename(finalBuildUrl, directoryUrl);
+					}
+
+				}
+
+				// // // throw the server folder in the bin
 				const serverUrl = new URL(_buildConfig.server);
 				await fs.promises.rm(serverUrl, { recursive: true, force: true });
 
@@ -225,14 +292,6 @@ export default function createIntegration(args?: Options): AstroIntegration {
 						)
 					);
 				}
-
-				if (isModeDirectory) {
-					const functionsUrl = new URL('functions/', _config.root);
-					await fs.promises.mkdir(functionsUrl, { recursive: true });
-
-					const directoryUrl = new URL('[[path]].js', functionsUrl);
-					await fs.promises.rename(finalBuildUrl, directoryUrl);
-				}
 			},
 		},
 	};
diff --git a/packages/integrations/cloudflare/src/server.directory.ts b/packages/integrations/cloudflare/src/server.directory.ts
index da2360557..f9f71a33b 100644
--- a/packages/integrations/cloudflare/src/server.directory.ts
+++ b/packages/integrations/cloudflare/src/server.directory.ts
@@ -61,5 +61,5 @@ export function createExports(manifest: SSRManifest) {
 		});
 	};
 
-	return { onRequest };
+	return { onRequest, manifest };
 }
diff --git a/packages/integrations/cloudflare/test/directory-split.test.js b/packages/integrations/cloudflare/test/directory-split.test.js
new file mode 100644
index 000000000..8bb6cd872
--- /dev/null
+++ b/packages/integrations/cloudflare/test/directory-split.test.js
@@ -0,0 +1,44 @@
+import { loadFixture } from './test-utils.js';
+import { expect } from 'chai';
+import cloudflare from '../dist/index.js';
+
+/** @type {import('./test-utils').Fixture} */
+describe('Cloudflare SSR split', () => {
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/split/',
+			adapter: cloudflare({ mode: 'directory' }),
+			output: "server",
+			build: {
+				split: true,
+				excludeMiddleware: false
+			},
+			vite: {
+				build: {
+					minify: false,
+				},
+			},
+		});
+		await fixture.build();
+	});
+
+	after(() => {
+		fixture.clean();
+	});
+
+	it('generates functions folders inside the project root, and checks that each page is emitted by astro', async () => {
+		expect(await fixture.pathExists('../functions')).to.be.true;
+		expect(await fixture.pathExists('../functions/index.js')).to.be.true;
+		expect(await fixture.pathExists('../functions/blog/cool.js')).to.be.true;
+		expect(await fixture.pathExists('../functions/blog/[post].js')).to.be.true;
+		expect(await fixture.pathExists('../functions/[person]/[car].js')).to.be.true;
+		expect(await fixture.pathExists('../functions/files/[[path]].js')).to.be.true;
+		expect(await fixture.pathExists('../functions/[language]/files/[[path]].js')).to.be.true;
+	});
+
+	it('generates pre-rendered files', async () => {
+		expect(await fixture.pathExists('./prerender/index.html')).to.be.true;
+	});
+});
diff --git a/packages/integrations/cloudflare/test/fixtures/split/package.json b/packages/integrations/cloudflare/test/fixtures/split/package.json
new file mode 100644
index 000000000..fd7dcc253
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "@test/astro-cloudflare-split",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "@astrojs/cloudflare": "workspace:*",
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/middleware.ts b/packages/integrations/cloudflare/test/fixtures/split/src/middleware.ts
new file mode 100644
index 000000000..a6ce640cb
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/middleware.ts
@@ -0,0 +1,10 @@
+import { defineMiddleware } from "astro/middleware";
+
+export const onRequest = defineMiddleware(({ locals, request }, next) => {
+  // intercept response data from a request
+  // optionally, transform the response by modifying `locals`
+  locals.title = "New title"
+
+  // return a Response or the result of calling `next()`
+  return next()
+});
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/[language]/files/[...path].astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/[language]/files/[...path].astro
new file mode 100644
index 000000000..84ad53228
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/[language]/files/[...path].astro
@@ -0,0 +1,37 @@
+---
+const files = [
+  {
+    slug: undefined,
+    title: 'Root level',
+  },
+  {
+    slug: 'test.png',
+    title: "One level"
+  },
+  {
+    slug: 'assets/test.png',
+    title: "Two levels"
+  },
+  {
+    slug: 'assets/images/test.png',
+    title: 'Three levels',
+  }
+];
+
+const { path } = Astro.params;
+const page = files.find((page) => page.slug === path);
+const { title } = page;
+
+---
+<html>
+	<body>
+		<h1>Files / Rest Parameters / {title}</h1>
+    <p>DEBUG: {path} </p>
+		<p><a href="/">index</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: yellow;
+		}
+	</style>
+</html>
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/[person]/[car].astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/[person]/[car].astro
new file mode 100644
index 000000000..f4fda9dc5
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/[person]/[car].astro
@@ -0,0 +1,14 @@
+---
+const { person, car } = Astro.params;
+---
+<html>
+	<body>
+		<h1> {person} / {car}</h1>
+		<p><a href="/">index</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: blue;
+		}
+	</style>
+</html>
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/blog/[post].astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/blog/[post].astro
new file mode 100644
index 000000000..7b0e1e5b8
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/blog/[post].astro
@@ -0,0 +1,14 @@
+---
+const { post } = Astro.params;
+---
+<html>
+	<body>
+		<h1>Blog / {post}</h1>
+		<p><a href="/">index</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: pink;
+		}
+	</style>
+</html>
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/blog/cool.astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/blog/cool.astro
new file mode 100644
index 000000000..7127282a4
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/blog/cool.astro
@@ -0,0 +1,11 @@
+<html>
+	<body>
+		<h1>Blog / Cool</h1>
+		<p><a href="/">index</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: orange;
+		}
+	</style>
+</html>
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/files/[...path].astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/files/[...path].astro
new file mode 100644
index 000000000..84ad53228
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/files/[...path].astro
@@ -0,0 +1,37 @@
+---
+const files = [
+  {
+    slug: undefined,
+    title: 'Root level',
+  },
+  {
+    slug: 'test.png',
+    title: "One level"
+  },
+  {
+    slug: 'assets/test.png',
+    title: "Two levels"
+  },
+  {
+    slug: 'assets/images/test.png',
+    title: 'Three levels',
+  }
+];
+
+const { path } = Astro.params;
+const page = files.find((page) => page.slug === path);
+const { title } = page;
+
+---
+<html>
+	<body>
+		<h1>Files / Rest Parameters / {title}</h1>
+    <p>DEBUG: {path} </p>
+		<p><a href="/">index</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: yellow;
+		}
+	</style>
+</html>
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/index.astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/index.astro
new file mode 100644
index 000000000..a7f564046
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/index.astro
@@ -0,0 +1,22 @@
+---
+const data = Astro.locals;
+---
+<html>
+	<body>
+		<h1>Index</h1>
+		<p>Middleware ({data.title})</p>
+		<p><a href="/prerender/">prerender</a></p>
+		<p><a href="/blog/cool/">sub-route</a></p>
+		<p><a href="/blog/dynamic-post/">dynamic route in static sub-route</a></p>
+		<p><a href="/mustermann/bmw/">dynamic route in dynamic sub-route</a></p>
+		<p><a href="/files/">rest parameters root level</a></p>
+		<p><a href="/files/test.png/">rest parameters one level</a></p>
+		<p><a href="/files/assets/test.png/">rest parameters two level</a></p>
+		<p><a href="/files/assets/images/test.png/">rest parameters three level</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: red;
+		}
+	</style>
+</html>
diff --git a/packages/integrations/cloudflare/test/fixtures/split/src/pages/prerender.astro b/packages/integrations/cloudflare/test/fixtures/split/src/pages/prerender.astro
new file mode 100644
index 000000000..bdda9b12c
--- /dev/null
+++ b/packages/integrations/cloudflare/test/fixtures/split/src/pages/prerender.astro
@@ -0,0 +1,14 @@
+---
+export const prerender = true;
+---
+<html>
+	<body>
+		<h1>Prerender</h1>
+		<p><a href="/">index</a></p>
+	</body>
+	<style>
+		h1 {
+			background-color: yellow;
+		}
+	</style>
+</html>
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c5649d326..ee0f3c091 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -3675,6 +3675,15 @@ importers:
         specifier: workspace:*
         version: link:../../../../../astro
 
+  packages/integrations/cloudflare/test/fixtures/split:
+    dependencies:
+      '@astrojs/cloudflare':
+        specifier: workspace:*
+        version: link:../../..
+      astro:
+        specifier: workspace:*
+        version: link:../../../../../astro
+
   packages/integrations/cloudflare/test/fixtures/with-solid-js:
     dependencies:
       '@astrojs/cloudflare':