attempt at revalidateTag

Author: kitop

package-lock.json

@@ -35,7 +35,7 @@
   "homepage": "https://github.com/netlify/next-runtime-minimal#readme",
   "dependencies": {
     "@fastly/http-compute-js": "1.1.1",
-    "@netlify/blobs": "^1.6.0",
+    "@netlify/blobs": "^3.2.0",
     "@netlify/build": "^29.20.6",
     "@netlify/functions": "^2.0.1",
     "@vercel/nft": "^0.24.3",

package.json

@@ -1,5 +1,16 @@
+import { getStore } from '@netlify/blobs'
+import { purgeCache } from '@netlify/functions'
 import type { CacheHandler, CacheHandlerContext } from 'next/dist/server/lib/incremental-cache/index.js'
 
+type TagsManifest = {
+  version: 1
+  items: { [tag: string]: { revalidatedAt: number } }
+}
+
+let tagsManifest: TagsManifest | undefined
+const tagsManifestPath = '_netlify/tags-manifest.json'
+const blobStore = getStore('TODO')
+
 /**
  * Netlify Cache Handler
  * (CJS format because Next.js doesn't support ESM yet)
@@ -9,6 +20,8 @@ export default class NetlifyCacheHandler implements CacheHandler {
 
   constructor(options: CacheHandlerContext) {
     this.options = options
+
+    this.loadTagsManifest()
   }
 
   // eslint-disable-next-line require-await, class-methods-use-this
@@ -25,5 +38,32 @@ export default class NetlifyCacheHandler implements CacheHandler {
   // eslint-disable-next-line class-methods-use-this, require-await
   public async revalidateTag(tag: string) {
     console.log('NetlifyCacheHandler.revalidateTag', tag)
+
+    await this.loadTagsManifest()
+    if (!tagsManifest) {
+      return
+    }
+
+    const data = tagsManifest.items[tag] || {}
+    data.revalidatedAt = Date.now()
+    tagsManifest.items[tag] = data
+
+    try {
+      blobStore.setJSON(tagsManifestPath, tagsManifest)
+    } catch (error: any) {
+      console.warn('Failed to update tags manifest.', error)
+    }
+    
+    purgeCache({ tags: [tag] })
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  private async loadTagsManifest() {
+    try {
+      tagsManifest = await blobStore.get(tagsManifestPath, {type: 'json'})
+    } catch (error: any) {
+      console.warn('Failed to fetch tags manifest.', error)
+      tagsManifest = { version: 1, items: {} }
+    }
   }
 }