From bb734c03c68634f48670296a7ea3463da43d654e Mon Sep 17 00:00:00 2001
From: Michal Piechowiak <misiek.piechowiak@gmail.com>
Date: Fri, 14 Jun 2024 13:01:05 +0200
Subject: [PATCH] decide wether to use APP_PAGE or PAGE kind based on actual
 next version

---
 src/build/content/prerendered.ts | 68 ++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 25 deletions(-)

diff --git a/src/build/content/prerendered.ts b/src/build/content/prerendered.ts
index 14dcab8972..727044b69c 100644
--- a/src/build/content/prerendered.ts
+++ b/src/build/content/prerendered.ts
@@ -6,6 +6,7 @@ import { trace } from '@opentelemetry/api'
 import { wrapTracer } from '@opentelemetry/api/experimental'
 import { glob } from 'fast-glob'
 import pLimit from 'p-limit'
+import { satisfies } from 'semver'
 
 import { encodeBlobKey } from '../../shared/blobkey.js'
 import type {
@@ -53,41 +54,40 @@ const buildPagesCacheValue = async (path: string): Promise<NetlifyCachedPageValu
 
 const buildAppCacheValue = async (
   path: string,
+  shouldUseAppPageKind: boolean,
 ): Promise<NetlifyCachedAppPageValue | NetlifyCachedPageValue> => {
   const meta = JSON.parse(await readFile(`${path}.meta`, 'utf-8'))
   const html = await readFile(`${path}.html`, 'utf-8')
 
-  // TODO: check actual next version and not rely on env var set by tests
-  const useOldStuff = process.env.NEXT_VERSION !== 'canary'
-  if (useOldStuff) {
-    const rsc = await readFile(`${path}.rsc`, 'utf-8').catch(() =>
-      readFile(`${path}.prefetch.rsc`, 'utf-8'),
-    )
-
-    // Next < v14.2.0 does not set meta.status when notFound() is called directly on a page
-    // Exclude Parallel routes, they are 404s when visited directly
-    if (
-      !meta.status &&
-      rsc.includes('NEXT_NOT_FOUND') &&
-      !meta.headers['x-next-cache-tags'].includes('/@')
-    ) {
-      meta.status = 404
-    }
+  // supporting both old and new cache kind for App Router pages - https://github.com/vercel/next.js/pull/65988
+  if (shouldUseAppPageKind) {
     return {
-      kind: 'PAGE',
+      kind: 'APP_PAGE',
       html,
-      pageData: rsc,
+      rscData: await readFile(`${path}.rsc`, 'base64').catch(() =>
+        readFile(`${path}.prefetch.rsc`, 'base64'),
+      ),
       ...meta,
     }
   }
 
-  // use new stuff
+  const rsc = await readFile(`${path}.rsc`, 'utf-8').catch(() =>
+    readFile(`${path}.prefetch.rsc`, 'utf-8'),
+  )
+
+  // Next < v14.2.0 does not set meta.status when notFound() is called directly on a page
+  // Exclude Parallel routes, they are 404s when visited directly
+  if (
+    !meta.status &&
+    rsc.includes('NEXT_NOT_FOUND') &&
+    !meta.headers['x-next-cache-tags'].includes('/@')
+  ) {
+    meta.status = 404
+  }
   return {
-    kind: 'APP_PAGE',
+    kind: 'PAGE',
     html,
-    rscData: await readFile(`${path}.rsc`, 'base64').catch(() =>
-      readFile(`${path}.prefetch.rsc`, 'base64'),
-    ),
+    pageData: rsc,
     ...meta,
   }
 }
@@ -120,6 +120,18 @@ export const copyPrerenderedContent = async (ctx: PluginContext): Promise<void>
 
       const limitConcurrentPrerenderContentHandling = pLimit(10)
 
+      // https://github.com/vercel/next.js/pull/65988 introduced Cache kind specific to pages in App Router (`APP_PAGE`).
+      // Before this change there was common kind for both Pages router and App router pages
+      // so we check Next.js version to decide how to generate cache values for App Router pages.
+      // Note: at time of writing this code, released 15@rc uses old kind for App Router pages, while 15.0.0@canary.13 and newer canaries use new kind.
+      // Looking at 15@rc release branch it was merging `canary` branch in, so the version constraint assumes that future 15@rc (and 15@latest) versions
+      // will use new kind for App Router pages.
+      const shouldUseAppPageKind = ctx.nextVersion
+        ? satisfies(ctx.nextVersion, '>=15.0.0-canary.13 <15.0.0-d || >15.0.0-rc.0', {
+            includePrerelease: true,
+          })
+        : false
+
       await Promise.all(
         Object.entries(manifest.routes).map(
           ([route, meta]): Promise<void> =>
@@ -142,7 +154,10 @@ export const copyPrerenderedContent = async (ctx: PluginContext): Promise<void>
                   value = await buildPagesCacheValue(join(ctx.publishDir, 'server/pages', key))
                   break
                 case meta.dataRoute?.endsWith('.rsc'):
-                  value = await buildAppCacheValue(join(ctx.publishDir, 'server/app', key))
+                  value = await buildAppCacheValue(
+                    join(ctx.publishDir, 'server/app', key),
+                    shouldUseAppPageKind,
+                  )
                   break
                 case meta.dataRoute === null:
                   value = await buildRouteCacheValue(
@@ -164,7 +179,10 @@ export const copyPrerenderedContent = async (ctx: PluginContext): Promise<void>
       if (existsSync(join(ctx.publishDir, `server/app/_not-found.html`))) {
         const lastModified = Date.now()
         const key = '/404'
-        const value = await buildAppCacheValue(join(ctx.publishDir, 'server/app/_not-found'))
+        const value = await buildAppCacheValue(
+          join(ctx.publishDir, 'server/app/_not-found'),
+          shouldUseAppPageKind,
+        )
         await writeCacheEntry(key, value, lastModified, ctx)
       }
     } catch (error) {