feat(vercel): incremental static generation + swr (#545)

src/presets/vercel.ts

@@ -1,4 +1,5 @@
-import { resolve } from 'pathe'
+import fsp from 'fs/promises'
+import { dirname, relative, resolve } from 'pathe'
 import { defu } from 'defu'
 import { withoutLeadingSlash } from 'ufo'
 import { writeFile } from '../utils'
@@ -34,6 +35,18 @@ export const vercel = defineNitroPreset({
         shouldAddHelpers: false
       }
       await writeFile(functionConfigPath, JSON.stringify(functionConfig, null, 2))
+
+      // Write prerender functions
+      for (const [key, value] of Object.entries(nitro.options.routeRules).filter(([_, value]) => value.cache && (value.cache.swr || value.cache.static))) {
+        if (!value.cache) { continue } // for type support
+        const funcPrefix = resolve(nitro.options.output.serverDir, '..' + generateEndpoint(key))
+        await fsp.mkdir(dirname(funcPrefix), { recursive: true })
+        await fsp.symlink('./' + relative(dirname(funcPrefix), nitro.options.output.serverDir), funcPrefix + '.func', 'junction')
+        await writeFile(funcPrefix + '.prerender-config.json', JSON.stringify({
+          expiration: value.cache.static ? false : typeof value.cache.swr === 'number' ? value.cache.swr : 60,
+          allowQuery: key.includes('/**') ? ['url'] : undefined
+        }))
+      }
     }
   }
 })
@@ -72,7 +85,6 @@ export const vercelEdge = defineNitroPreset({
 })
 
 function generateBuildConfig (nitro: Nitro) {
-  // const overrides = generateOverrides(nitro._prerenderedRoutes?.filter(r => r.fileName !== r.route) || [])
   return defu(nitro.options.vercel?.config, <VercelBuildConfigV3> {
     version: 3,
     overrides: Object.fromEntries(
@@ -112,10 +124,20 @@ function generateBuildConfig (nitro: Nitro) {
       {
         handle: 'filesystem'
       },
+      ...Object.entries(nitro.options.routeRules)
+        .filter(([key, value]) => value.cache && (value.cache.swr || value.cache.static) && key.includes('/**'))
+        .map(([key]) => ({
+          src: key.replace(/^(.*)\/\*\*/, '(?<url>$1/.*)'),
+          dest: generateEndpoint(key) + '?url=$url'
+        })),
       {
         src: '/(.*)',
         dest: '/__nitro'
       }
     ]
   })
 }
+
+function generateEndpoint (url: string) {
+  return url.includes('/**') ? '/__nitro-' + withoutLeadingSlash(url.replace(/\/\*\*.*/, '').replace(/[^a-z]/g, '-')) : url
+}

src/runtime/entries/vercel.ts

@@ -1,5 +1,17 @@
 import '#internal/nitro/virtual/polyfill'
-import { toNodeListener } from 'h3'
+import { toNodeListener, NodeListener } from 'h3'
+import { parseQuery } from 'ufo'
 import { nitroApp } from '../app'
 
-export default toNodeListener(nitroApp.h3App)
+const handler = toNodeListener(nitroApp.h3App)
+
+export default <NodeListener> function (req, res) {
+  const query = req.headers['x-now-route-matches'] as string
+  if (query) {
+    const { url } = parseQuery(query)
+    if (url) {
+      req.url = url as string
+    }
+  }
+  return handler(req, res)
+}

test/presets/netlify.test.ts

@@ -37,6 +37,8 @@ describe('nitro:preset:netlify', async () => {
       /rules/nested/*	/base	302
       /rules/redirect/obj	https://nitro.unjs.io/	301
       /rules/redirect	/base	302
+      /rules/swr-ttl/*	/.netlify/builders/server 200
+      /rules/swr/*	/.netlify/builders/server 200
       /rules/static	/.netlify/builders/server 200
       /* /.netlify/functions/server 200"
     `)

test/presets/vercel.test.ts

@@ -95,6 +95,14 @@ describe('nitro:preset:vercel', async () => {
           {
             "handle": "filesystem",
           },
+          {
+            "dest": "/__nitro--rules-swr?url=$url",
+            "src": "(?<url>/rules/swr/.*)",
+          },
+          {
+            "dest": "/__nitro--rules-swr-ttl?url=$url",
+            "src": "(?<url>/rules/swr-ttl/.*)",
+          },
           {
             "dest": "/__nitro",
             "src": "/(.*)",

test/tests.ts

@@ -39,6 +39,8 @@ export async function setupTest (preset) {
       '/rules/cors': { cors: true, headers: { 'access-control-allowed-methods': 'GET' } },
       '/rules/redirect': { redirect: '/base' },
       '/rules/static': { static: true },
+      '/rules/swr/**': { swr: true },
+      '/rules/swr-ttl/**': { swr: 60 },
       '/rules/redirect/obj': {
         redirect: { to: 'https://nitro.unjs.io/', statusCode: 308 }
       },