perf: add HTTP Link header (experimental)

Author: userquin

modules/route-rules.ts

@@ -0,0 +1,184 @@
+import type { NitroConfig } from 'nitropack'
+import { defineNuxtModule } from 'nuxt/kit'
+import { resolve } from 'node:path'
+import { readFile } from 'node:fs/promises'
+import { isPreview, isProduction } from '../config/env'
+import { ELEMENT_NODE, parse, walk } from 'ultrahtml'
+// import type { Manifest } from "@voidzero-dev/vite-plus-core";
+
+// TODO: use the context and maybe we should move the module to a folder
+// interface RouteRulesContext {
+//   globalFonts: string[]
+//   manifest: Manifest
+// }
+
+// Cache for global fonts extracted from entry CSS
+let globalFonts: string[] = []
+
+async function extractFontsFromCss(cssPath: string): Promise<string[]> {
+  try {
+    const content = await readFile(cssPath, 'utf8')
+    const fontUrls = new Set<string>()
+    // original with backtracking => oxlint complains
+    // const regex = /url\(\s*(?:["']?)([^"')]+?\.woff2)(?:["']?)\s*\)/g
+
+    // Regex to capture woff2 urls: url(../_fonts/...) or url("../_fonts/...")
+    // Captures the content inside url(...) stripping quotes if present
+    // Optimized to avoid ReDoS (super-linear backtracking)
+    const regex = /url\(\s*['"]?([^\s'")\\]+\.woff2)(?:'|")?\s*\)/g
+
+    let match
+    while ((match = regex.exec(content)) !== null) {
+      const url = match[1]
+      if (url) {
+        fontUrls.add(url)
+      }
+    }
+    return Array.from(fontUrls)
+  } catch (e) {
+    console.error(`Failed to extract fonts from ${cssPath}:`, e)
+    return []
+  }
+}
+
+async function collectLinkHeader(path: string): Promise<string | undefined> {
+  try {
+    const html = await readFile(path, 'utf8')
+    const ast = parse(html)
+    const links: string[] = []
+
+    // Add global fonts (preload)
+    for (const font of globalFonts) {
+      let fontPath = font
+      if (font.startsWith('../')) {
+        fontPath = font.substring(2) // Remove ..
+      }
+      if (!fontPath.startsWith('/')) {
+        fontPath = '/' + fontPath
+      }
+      links.push(`<${fontPath}>; rel=preload; as=font; crossorigin`)
+    }
+
+    await walk(ast, node => {
+      if (node.type === ELEMENT_NODE) {
+        if (node.name === 'script') {
+          const type = node.attributes.type
+          const src = node.attributes.src
+          if (type === 'module' && src && !src.startsWith('http')) {
+            const cors =
+              node.attributes.crossorigin === '' || node.attributes.crossorigin === 'true'
+                ? '; crossorigin'
+                : ''
+            links.push(`<${src}>; rel=modulepreload; as=script${cors}`)
+          }
+        } else if (node.name === 'link') {
+          const rel = node.attributes.rel
+          const href = node.attributes.href
+          if (rel === 'modulepreload' && href && !href.startsWith('http')) {
+            const cors =
+              node.attributes.crossorigin === '' || node.attributes.crossorigin === 'true'
+                ? '; crossorigin'
+                : ''
+            links.push(`<${href}>; rel=modulepreload; as=script${cors}`)
+          } else if (rel === 'stylesheet' && href && !href.startsWith('http')) {
+            // Preload CSS
+            const cors =
+              node.attributes.crossorigin === '' || node.attributes.crossorigin === 'true'
+                ? '; crossorigin'
+                : ''
+            links.push(`<${href}>; rel=preload; as=style ${cors}`)
+          }
+        }
+      }
+    })
+
+    // console.log(path, links)
+
+    return links.length > 0 ? links.join(', ') : undefined
+  } catch (e) {
+    console.error(`error collecting link header for ${path}`, e)
+    // Ignore file not found (route might not be prerendered yet or is dynamic)
+    return undefined
+  }
+}
+
+async function collectLinkHeaders(outDir: string, options: NitroConfig): Promise<NitroConfig> {
+  const routeRules = Object.assign({}, options.routeRules)
+
+  for (const route of Object.keys(routeRules)) {
+    const rule = routeRules[route]
+    if (
+      !rule?.prerender ||
+      route.includes('*') ||
+      route.endsWith('.html') ||
+      route.endsWith('.json')
+    ) {
+      continue
+    }
+
+    let htmlPath = resolve(outDir, route === '/' ? 'index.html' : `${route.slice(1)}/index.html`)
+
+    const linkHeader = await collectLinkHeader(htmlPath)
+    if (linkHeader) {
+      routeRules[route]!.headers ??= {}
+      routeRules[route]!.headers.Link = linkHeader
+    }
+  }
+
+  return { routeRules }
+}
+
+export default defineNuxtModule({
+  meta: {
+    name: 'npmx:route-rules',
+  },
+  setup(_options, nuxt) {
+    // TODO: use this for local test with http/1.1 and node preset
+    /*
+    if (nuxt.options.dev || process.env.TEST /!* || !(isPreview || isProduction)*!/) {
+      return
+    }
+*/
+    if (nuxt.options.dev || process.env.TEST || !(isPreview || isProduction)) {
+      return
+    }
+
+    let outDir = '../.output/public'
+
+    nuxt.hook('nitro:init', nitro => {
+      const nitroConfig = nitro.options
+      const publicDir = nitroConfig.output?.publicDir ?? nuxt.options.nitro?.output?.publicDir
+      outDir = publicDir ? resolve(publicDir) : resolve(nuxt.options.buildDir, '../.output/public')
+      nitro.hooks.hook('prerender:done', async () => {
+        const updates = await collectLinkHeaders(outDir, nitro.options)
+        await nitro.updateConfig(updates)
+        // console.log(updates)
+      })
+    })
+
+    // Hook into build:manifest to find the entry CSS and extract fonts
+    nuxt.hook('build:manifest', async manifest => {
+      // console.log(manifest)
+      const entry = Object.values(manifest).find(r => r.isEntry)
+      if (entry && entry.css) {
+        for (const cssFile of entry.css) {
+          // Try to resolve CSS path. It might be in _nuxt/ or root of dist/client
+          // Based on log: node_modules/.cache/nuxt/.nuxt/dist/client/_nuxt/pages...css
+          // nuxt.options.buildDir points to .nuxt
+          let cssPath = resolve('node_modules/.cache/nuxt/.nuxt/dist/client/_nuxt', cssFile)
+
+          // If cssFile doesn't start with _nuxt but is inside it, adjust
+          // But usually manifest paths are relative to public path or build output
+
+          // Fallback/Check: if file doesn't exist, try adding _nuxt if missing
+          // But let's trust resolve first.
+
+          const fonts = await extractFontsFromCss(cssPath)
+          globalFonts.push(...fonts)
+        }
+      }
+
+      // console.log(globalFonts)
+    })
+  },
+})

package.json

@@ -100,6 +100,7 @@
     "std-env": "3.10.0",
     "tinyglobby": "0.2.15",
     "ufo": "1.6.3",
+    "ultrahtml": "1.6.0",
     "unocss": "66.6.0",
     "unplugin-vue-router": "0.19.2",
     "valibot": "1.2.0",