Redirects (#7067)

* Redirects spike

* Allow redirects in static mode

* Support in Netlify as well

* Adding a changeset

* Rename file

* Fix build problem

* Refactor to be more modular

* Fix location ref

* Late test should only run in SSR

* Support redirects in Netlify SSR configuration (#7167)

* Implement support for dynamic routes in redirects (#7173)

* Implement support for dynamic routes in redirects

* Remove the .only

* No need to special-case redirects in static build

* Implement support for redirects config in the Vercel adapter (#7182)

* Implement support for redirects config in the Vercel adapter

* Remove unused condition

* Move to a internal helper package

* Add support for the object notation in redirects

* Use status 308 for non-GET redirects (#7186)

* Implement redirects in Cloudflare (#7198)

* Implement redirects in Cloudflare

* Fix build

* Update tests b/c of new ordering

* Debug issue

* Use posix.join

* Update packages/underscore-redirects/package.json

Co-authored-by: Emanuele Stoppa <my.burning@gmail.com>

* Update based on review comments

* Update broken test

---------

Co-authored-by: Emanuele Stoppa <my.burning@gmail.com>

* Test that redirects can come from middleware (#7213)

* Test that redirects can come from middleware

* Allow non-promise returns for middleware

* Implement priority (#7210)

* Refactor

* Fix netlify test ordering

* Fix ordering again

* Redirects: Allow preventing the output of the static HTML file (#7245)

* Do a simple push for priority

* Adding changesets

* Put the implementation behind a flag.

* Self review

* Update .changeset/chatty-actors-stare.md

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* Update packages/astro/src/@types/astro.ts

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* Update packages/astro/src/@types/astro.ts

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* Update packages/astro/src/@types/astro.ts

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* Update packages/astro/src/@types/astro.ts

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

* Update docs on dynamic restrictions.

* Update packages/astro/src/@types/astro.ts

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

* Update packages/astro/src/@types/astro.ts

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

* Code review changes

* Document netlify static adapter

* Update packages/astro/src/@types/astro.ts

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

* Slight reword

* Update .changeset/twenty-suns-vanish.md

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

* Add a note about public/_redirects file

* Update packages/astro/src/@types/astro.ts

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

---------

Co-authored-by: Emanuele Stoppa <my.burning@gmail.com>
Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>
Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>
Co-authored-by: Nate Moore <natemoo-re@users.noreply.github.com>

11 files changed, 212 insertions, 130 deletions

diff --git a/packages/integrations/netlify/README.md b/packages/integrations/netlify/README.md
index ec72f2a2c..cee5fa5c2 100644
--- a/packages/integrations/netlify/README.md
+++ b/packages/integrations/netlify/README.md
@@ -74,6 +74,30 @@ export default defineConfig({
 });
 ```
 
+### Static sites
+
+For static sites you usually don't need an adapter. However, if you use `redirects` configuration (experimental) in your Astro config, the Netlify adapter can be used to translate this to the proper `_redirects` format. 
+
+```js
+import { defineConfig } from 'astro/config';
+import netlify from '@astrojs/netlify/static';
+
+export default defineConfig({
+  adapter: netlify(),
+
+  redirects: {
+    '/blog/old-post': '/blog/new-post'
+  },
+  experimental: {
+    redirects: true
+  }
+});
+```
+
+Once you run `astro build` there will be a `dist/_redirects` file. Netlify will use that to properly route pages in production.
+
+> __Note__, you can still include a `public/_redirects` file for manual redirects. Any redirects you specify in the redirects config are appended to the end of your own.
+
 ## Usage
 
 [Read the full deployment guide here.](https://docs.astro.build/en/guides/deploy/netlify/)
diff --git a/packages/integrations/netlify/package.json b/packages/integrations/netlify/package.json
index 26ba3873f..64a106c84 100644
--- a/packages/integrations/netlify/package.json
+++ b/packages/integrations/netlify/package.json
@@ -37,6 +37,7 @@
     "test": "npm run test-fn"
   },
   "dependencies": {
+    "@astrojs/underscore-redirects": "^0.1.0",
     "@astrojs/webapi": "^2.2.0",
     "@netlify/functions": "^1.0.0",
     "esbuild": "^0.15.18"
diff --git a/packages/integrations/netlify/src/index.ts b/packages/integrations/netlify/src/index.ts
index fd7fd5fed..510e560f1 100644
--- a/packages/integrations/netlify/src/index.ts
+++ b/packages/integrations/netlify/src/index.ts
@@ -1,2 +1,3 @@
 export { netlifyEdgeFunctions } from './integration-edge-functions.js';
 export { netlifyFunctions as default, netlifyFunctions } from './integration-functions.js';
+export { netlifyStatic } from './integration-static.js';
diff --git a/packages/integrations/netlify/src/integration-static.ts b/packages/integrations/netlify/src/integration-static.ts
new file mode 100644
index 000000000..8814f9d2a
--- /dev/null
+++ b/packages/integrations/netlify/src/integration-static.ts
@@ -0,0 +1,26 @@
+import type { AstroAdapter, AstroConfig, AstroIntegration, RouteData } from 'astro';
+import type { Args } from './netlify-functions.js';
+import { createRedirects } from './shared.js';
+
+export function netlifyStatic(): AstroIntegration {
+	let _config: any;
+	return {
+		name: '@astrojs/netlify',
+		hooks: {
+			'astro:config:setup': ({ updateConfig }) => {
+				updateConfig({
+					build: {
+						// Do not output HTML redirects because we are building a `_redirects` file.
+						redirects: false,
+					},
+				});
+			},
+			'astro:config:done': ({ config }) => {
+				_config = config;
+			},
+			'astro:build:done': async ({ dir, routes }) => {
+				await createRedirects(_config, routes, dir, '', 'static');
+			}
+		}
+	};
+}
diff --git a/packages/integrations/netlify/src/shared.ts b/packages/integrations/netlify/src/shared.ts
index 78a61a800..d452ada10 100644
--- a/packages/integrations/netlify/src/shared.ts
+++ b/packages/integrations/netlify/src/shared.ts
@@ -1,145 +1,25 @@
 import type { AstroConfig, RouteData } from 'astro';
-import fs from 'fs';
-
-type RedirectDefinition = {
-	dynamic: boolean;
-	input: string;
-	target: string;
-	weight: 0 | 1;
-	status: 200 | 404;
-};
+import { createRedirectsFromAstroRoutes } from '@astrojs/underscore-redirects';
+import fs from 'node:fs';
 
 export async function createRedirects(
 	config: AstroConfig,
 	routes: RouteData[],
 	dir: URL,
 	entryFile: string,
-	type: 'functions' | 'edge-functions' | 'builders'
+	type: 'functions' | 'edge-functions' | 'builders' | 'static'
 ) {
-	const _redirectsURL = new URL('./_redirects', dir);
 	const kind = type ?? 'functions';
+	const dynamicTarget = `/.netlify/${kind}/${entryFile}`;
+	const _redirectsURL = new URL('./_redirects', dir);
 
-	const definitions: RedirectDefinition[] = [];
-
-	for (const route of routes) {
-		if (route.pathname) {
-			if (route.distURL) {
-				definitions.push({
-					dynamic: false,
-					input: route.pathname,
-					target: prependForwardSlash(route.distURL.toString().replace(dir.toString(), '')),
-					status: 200,
-					weight: 1,
-				});
-			} else {
-				definitions.push({
-					dynamic: false,
-					input: route.pathname,
-					target: `/.netlify/${kind}/${entryFile}`,
-					status: 200,
-					weight: 1,
-				});
-
-				if (route.route === '/404') {
-					definitions.push({
-						dynamic: true,
-						input: '/*',
-						target: `/.netlify/${kind}/${entryFile}`,
-						status: 404,
-						weight: 0,
-					});
-				}
-			}
-		} else {
-			const pattern =
-				'/' +
-				route.segments
-					.map(([part]) => {
-						//(part.dynamic ? '*' : part.content)
-						if (part.dynamic) {
-							if (part.spread) {
-								return '*';
-							} else {
-								return ':' + part.content;
-							}
-						} else {
-							return part.content;
-						}
-					})
-					.join('/');
-
-			if (route.distURL) {
-				const target =
-					`${pattern}` + (config.build.format === 'directory' ? '/index.html' : '.html');
-				definitions.push({
-					dynamic: true,
-					input: pattern,
-					target,
-					status: 200,
-					weight: 1,
-				});
-			} else {
-				definitions.push({
-					dynamic: true,
-					input: pattern,
-					target: `/.netlify/${kind}/${entryFile}`,
-					status: 200,
-					weight: 1,
-				});
-			}
-		}
-	}
-
-	let _redirects = prettify(definitions);
+	const _redirects = createRedirectsFromAstroRoutes({
+		config, routes, dir, dynamicTarget
+	});
+	const content = _redirects.print();
 
 	// Always use appendFile() because the redirects file could already exist,
 	// e.g. due to a `/public/_redirects` file that got copied to the output dir.
 	// If the file does not exist yet, appendFile() automatically creates it.
-	await fs.promises.appendFile(_redirectsURL, _redirects, 'utf-8');
-}
-
-function prettify(definitions: RedirectDefinition[]) {
-	let minInputLength = 0,
-		minTargetLength = 0;
-	definitions.sort((a, b) => {
-		// Find the longest input, so we can format things nicely
-		if (a.input.length > minInputLength) {
-			minInputLength = a.input.length;
-		}
-		if (b.input.length > minInputLength) {
-			minInputLength = b.input.length;
-		}
-
-		// Same for the target
-		if (a.target.length > minTargetLength) {
-			minTargetLength = a.target.length;
-		}
-		if (b.target.length > minTargetLength) {
-			minTargetLength = b.target.length;
-		}
-
-		// Sort dynamic routes on top
-		return b.weight - a.weight;
-	});
-
-	let _redirects = '';
-	// Loop over the definitions
-	definitions.forEach((defn, i) => {
-		// Figure out the number of spaces to add. We want at least 4 spaces
-		// after the input. This ensure that all targets line up together.
-		let inputSpaces = minInputLength - defn.input.length + 4;
-		let targetSpaces = minTargetLength - defn.target.length + 4;
-		_redirects +=
-			(i === 0 ? '' : '\n') +
-			defn.input +
-			' '.repeat(inputSpaces) +
-			defn.target +
-			' '.repeat(Math.abs(targetSpaces)) +
-			defn.status;
-	});
-	return _redirects;
-}
-
-function prependForwardSlash(str: string) {
-	return str[0] === '/' ? str : '/' + str;
+	await fs.promises.appendFile(_redirectsURL, content, 'utf-8');
 }
diff --git a/packages/integrations/netlify/test/functions/redirects.test.js b/packages/integrations/netlify/test/functions/redirects.test.js
new file mode 100644
index 000000000..8a6d36694
--- /dev/null
+++ b/packages/integrations/netlify/test/functions/redirects.test.js
@@ -0,0 +1,44 @@
+import { expect } from 'chai';
+import { load as cheerioLoad } from 'cheerio';
+import { loadFixture, testIntegration } from './test-utils.js';
+import netlifyAdapter from '../../dist/index.js';
+import { fileURLToPath } from 'url';
+
+describe('SSG - Redirects', () => {
+	/** @type {import('../../../astro/test/test-utils').Fixture} */
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: new URL('../static/fixtures/redirects/', import.meta.url).toString(),
+			output: 'server',
+			adapter: netlifyAdapter({
+				dist: new URL('../static/fixtures/redirects/dist/', import.meta.url),
+			}),
+			site: `http://example.com`,
+			integrations: [testIntegration()],
+			redirects: {
+				'/other': '/'
+			},
+			experimental: {
+				redirects: true,
+			},
+		});
+		await fixture.build();
+	});
+
+	it('Creates a redirects file', async () => {
+		let redirects = await fixture.readFile('/_redirects');
+		let parts = redirects.split(/\s+/);
+		expect(parts).to.deep.equal([
+			'/other', '/', '301',
+			// This uses the dynamic Astro.redirect, so we don't know that it's a redirect
+			// until runtime. This is correct!
+			'/nope', '/.netlify/functions/entry', '200',
+			'/', '/.netlify/functions/entry', '200',
+
+			// A real route
+			'/team/articles/*', '/.netlify/functions/entry', '200',
+		]);
+	});
+});
diff --git a/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/index.astro b/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/index.astro
new file mode 100644
index 000000000..53e029f04
--- /dev/null
+++ b/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/index.astro
@@ -0,0 +1,6 @@
+<html>
+<head><title>Testing</title></head>
+<body>
+	<h1>Testing</h1>
+</body>
+</html>
diff --git a/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/nope.astro b/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/nope.astro
new file mode 100644
index 000000000..f48d767ee
--- /dev/null
+++ b/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/nope.astro
@@ -0,0 +1,3 @@
+---
+return Astro.redirect('/');
+---
diff --git a/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/team/articles/[...slug].astro b/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/team/articles/[...slug].astro
new file mode 100644
index 000000000..716d3bd5d
--- /dev/null
+++ b/packages/integrations/netlify/test/static/fixtures/redirects/src/pages/team/articles/[...slug].astro
@@ -0,0 +1,25 @@
+---
+export const getStaticPaths = (async () => {
+  const posts = [
+		{ slug: 'one', data: {draft: false, title: 'One'} },
+		{ slug: 'two', data: {draft: false, title: 'Two'} }
+	];
+  return posts.map((post) => {
+    return {
+      params: { slug: post.slug },
+      props: { draft: post.data.draft, title: post.data.title },
+    };
+  });
+})
+
+const { slug } = Astro.params;
+const { title } = Astro.props;
+---
+<html>
+	<head>
+		<title>{ title }</title>
+	</head>
+	<body>
+		<h1>{ title }</h1>
+	</body>
+</html>
diff --git a/packages/integrations/netlify/test/static/redirects.test.js b/packages/integrations/netlify/test/static/redirects.test.js
new file mode 100644
index 000000000..0b153b31c
--- /dev/null
+++ b/packages/integrations/netlify/test/static/redirects.test.js
@@ -0,0 +1,43 @@
+import { expect } from 'chai';
+import { loadFixture, testIntegration } from './test-utils.js';
+import { netlifyStatic } from '../../dist/index.js';
+
+describe('SSG - Redirects', () => {
+	/** @type {import('../../../astro/test/test-utils').Fixture} */
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: new URL('./fixtures/redirects/', import.meta.url).toString(),
+			output: 'static',
+			adapter: netlifyStatic(),
+			experimental: {
+				redirects: true,
+			},
+			site: `http://example.com`,
+			integrations: [testIntegration()],
+			redirects: {
+				'/other': '/',
+				'/two': {
+					status: 302,
+					destination: '/'
+				},
+				'/blog/[...slug]': '/team/articles/[...slug]'
+			}
+		});
+		await fixture.build();
+	});
+
+	it('Creates a redirects file', async () => {
+		let redirects = await fixture.readFile('/_redirects');
+		let parts = redirects.split(/\s+/);
+		expect(parts).to.deep.equal([
+			'/two', '/', '302',
+			'/other', '/', '301',
+			'/nope', '/', '301',
+
+			'/blog/*', '/team/articles/*/index.html', '301',
+			'/team/articles/*', '/team/articles/*/index.html', '200',
+		]);
+	});
+});
diff --git a/packages/integrations/netlify/test/static/test-utils.js b/packages/integrations/netlify/test/static/test-utils.js
new file mode 100644
index 000000000..02b5d2ad9
--- /dev/null
+++ b/packages/integrations/netlify/test/static/test-utils.js
@@ -0,0 +1,29 @@
+// @ts-check
+import { fileURLToPath } from 'url';
+
+export * from '../../../../astro/test/test-utils.js';
+
+/**
+ *
+ * @returns {import('../../../../astro/dist/types/@types/astro').AstroIntegration}
+ */
+export function testIntegration() {
+	return {
+		name: '@astrojs/netlify/test-integration',
+		hooks: {
+			'astro:config:setup': ({ updateConfig }) => {
+				updateConfig({
+					vite: {
+						resolve: {
+							alias: {
+								'@astrojs/netlify/netlify-functions.js': fileURLToPath(
+									new URL('../../dist/netlify-functions.js', import.meta.url)
+								),
+							},
+						},
+					},
+				});
+			},
+		},
+	};
+}