From e0b69973f840bfa281fae209da1f1c674c1301a8 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Mon, 13 Sep 2021 23:56:11 -0400
Subject: [PATCH] feat: support `<script client>` in mpa mode

---
 src/node/build/build.ts          |  6 ++-
 src/node/build/buildMPAClient.ts | 45 ++++++++++++++++++++
 src/node/build/bundle.ts         | 22 ++++++++--
 src/node/build/render.ts         | 72 ++++++++++++++++++++++----------
 src/node/config.ts               |  1 +
 src/node/markdownToVue.ts        |  7 +++-
 src/node/plugin.ts               | 33 +++++++++++----
 7 files changed, 152 insertions(+), 34 deletions(-)
 create mode 100644 src/node/build/buildMPAClient.ts

diff --git a/src/node/build/build.ts b/src/node/build/build.ts
index 32f40225e142..a8934b1e08fd 100644
--- a/src/node/build/build.ts
+++ b/src/node/build/build.ts
@@ -21,7 +21,7 @@ export async function build(
   }
 
   try {
-    const [clientResult, serverResult, pageToHashMap] = await bundle(
+    const { clientResult, serverResult, pageToHashMap } = await bundle(
       siteConfig,
       buildOptions
     )
@@ -36,7 +36,9 @@ export async function build(
           (chunk) => chunk.type === 'chunk' && chunk.isEntry
         ) as OutputChunk)
 
-      const cssChunk = (clientResult || serverResult).output.find(
+      const cssChunk = (
+        siteConfig.mpa ? serverResult : clientResult
+      ).output.find(
         (chunk) => chunk.type === 'asset' && chunk.fileName.endsWith('.css')
       ) as OutputAsset
 
diff --git a/src/node/build/buildMPAClient.ts b/src/node/build/buildMPAClient.ts
new file mode 100644
index 000000000000..cb0a240092f4
--- /dev/null
+++ b/src/node/build/buildMPAClient.ts
@@ -0,0 +1,45 @@
+import { build } from 'vite'
+import { SiteConfig } from '..'
+
+const virtualEntry = 'client.js'
+
+export async function buildMPAClient(
+  js: Record<string, string>,
+  config: SiteConfig
+) {
+  const files = Object.keys(js)
+  const themeFiles = files.filter((f) => !f.endsWith('.md'))
+  const pages = files.filter((f) => f.endsWith('.md'))
+
+  return build({
+    root: config.srcDir,
+    base: config.site.base,
+    logLevel: 'warn',
+    build: {
+      emptyOutDir: false,
+      outDir: config.outDir,
+      rollupOptions: {
+        input: [virtualEntry, ...pages]
+      }
+    },
+    plugins: [
+      {
+        name: 'vitepress-mpa-client',
+        resolveId(id) {
+          if (id === virtualEntry) {
+            return id
+          }
+        },
+        load(id) {
+          if (id === virtualEntry) {
+            return themeFiles
+              .map((file) => `import ${JSON.stringify(file)}`)
+              .join('\n')
+          } else if (id in js) {
+            return js[id]
+          }
+        }
+      }
+    ]
+  })
+}
diff --git a/src/node/build/bundle.ts b/src/node/build/bundle.ts
index 18cdd40b7bf2..bb7368477643 100644
--- a/src/node/build/bundle.ts
+++ b/src/node/build/bundle.ts
@@ -7,6 +7,7 @@ import { SiteConfig } from '../config'
 import { RollupOutput } from 'rollup'
 import { build, BuildOptions, UserConfig as ViteUserConfig } from 'vite'
 import { createVitePressPlugin } from '../plugin'
+import { buildMPAClient } from './buildMPAClient'
 
 export const okMark = '\x1b[32m✓\x1b[0m'
 export const failMark = '\x1b[31m✖\x1b[0m'
@@ -15,9 +16,14 @@ export const failMark = '\x1b[31m✖\x1b[0m'
 export async function bundle(
   config: SiteConfig,
   options: BuildOptions
-): Promise<[RollupOutput, RollupOutput, Record<string, string>]> {
+): Promise<{
+  clientResult: RollupOutput
+  serverResult: RollupOutput
+  pageToHashMap: Record<string, string>
+}> {
   const { root, srcDir } = config
   const pageToHashMap = Object.create(null)
+  const clientJSMap = Object.create(null)
 
   // define custom rollup input
   // this is a multi-entry build - every page is considered an entry chunk
@@ -39,7 +45,13 @@ export async function bundle(
     root: srcDir,
     base: config.site.base,
     logLevel: 'warn',
-    plugins: createVitePressPlugin(root, config, ssr, pageToHashMap),
+    plugins: createVitePressPlugin(
+      root,
+      config,
+      ssr,
+      pageToHashMap,
+      clientJSMap
+    ),
     // @ts-ignore
     ssr: {
       noExternal: ['vitepress']
@@ -112,9 +124,13 @@ export async function bundle(
     if (fs.existsSync(publicDir)) {
       await fs.copy(publicDir, config.outDir)
     }
+    // build <script client> bundle
+    if (Object.keys(clientJSMap).length) {
+      clientResult = (await buildMPAClient(clientJSMap, config)) as RollupOutput
+    }
   }
 
-  return [clientResult, serverResult, pageToHashMap]
+  return { clientResult, serverResult, pageToHashMap }
 }
 
 const adComponentRE = /(?:Carbon|BuySell)Ads/
diff --git a/src/node/build/render.ts b/src/node/build/render.ts
index 52aee1f0e091..de1a5891da57 100644
--- a/src/node/build/render.ts
+++ b/src/node/build/render.ts
@@ -4,15 +4,16 @@ import { SiteConfig, resolveSiteDataByRoute } from '../config'
 import { HeadConfig } from '../shared'
 import { normalizePath } from 'vite'
 import { RollupOutput, OutputChunk, OutputAsset } from 'rollup'
+import { slash } from '../utils/slash'
 
 const escape = require('escape-html')
 
 export async function renderPage(
   config: SiteConfig,
   page: string, // foo.md
-  result: RollupOutput,
-  appChunk: OutputChunk,
-  cssChunk: OutputAsset,
+  result: RollupOutput | null,
+  appChunk: OutputChunk | undefined,
+  cssChunk: OutputAsset | undefined,
   pageToHashMap: Record<string, string>,
   hashMapString: string
 ) {
@@ -39,20 +40,26 @@ export async function renderPage(
   ))
   const pageData = JSON.parse(__pageData)
 
-  const preloadLinks = config.mpa
-    ? ''
-    : [
-        // resolve imports for index.js + page.md.js and inject script tags for
-        // them as well so we fetch everything as early as possible without having
-        // to wait for entry chunks to parse
-        ...resolvePageImports(config, page, result, appChunk),
-        pageClientJsFileName,
-        appChunk.fileName
-      ]
-        .map((file) => {
-          return `<link rel="modulepreload" href="${siteData.base}${file}">`
-        })
-        .join('\n    ')
+  const preloadLinks = (
+    config.mpa
+      ? appChunk
+        ? [appChunk.fileName]
+        : []
+      : result && appChunk
+      ? [
+          // resolve imports for index.js + page.md.js and inject script tags for
+          // them as well so we fetch everything as early as possible without having
+          // to wait for entry chunks to parse
+          ...resolvePageImports(config, page, result, appChunk),
+          pageClientJsFileName,
+          appChunk.fileName
+        ]
+      : []
+  )
+    .map((file) => {
+      return `<link rel="modulepreload" href="${siteData.base}${file}">`
+    })
+    .join('\n    ')
 
   const stylesheetLink = cssChunk
     ? `<link rel="stylesheet" href="${siteData.base}${cssChunk.fileName}">`
@@ -69,6 +76,23 @@ export async function renderPage(
     ...filterOutHeadDescription(pageData.frontmatter.head)
   )
 
+  let inlinedScript = ''
+  if (config.mpa && result) {
+    const matchingChunk = result.output.find(
+      (chunk) =>
+        chunk.type === 'chunk' &&
+        chunk.facadeModuleId === slash(path.join(config.srcDir, page))
+    ) as OutputChunk
+    if (matchingChunk) {
+      if (!matchingChunk.code.includes('import')) {
+        inlinedScript = `<script type="module">${matchingChunk.code}</script>`
+        fs.removeSync(path.resolve(config.outDir, matchingChunk.fileName))
+      } else {
+        inlinedScript = `<script type="module" src="${siteData.base}${matchingChunk.fileName}"></script>`
+      }
+    }
+  }
+
   const html = `
 <!DOCTYPE html>
 <html lang="${siteData.lang}">
@@ -87,10 +111,16 @@ export async function renderPage(
     <div id="app">${content}</div>
     ${
       config.mpa
-        ? ``
-        : `<script>__VP_HASH_MAP__ = JSON.parse(${hashMapString})</script>` +
-          `<script type="module" async src="${siteData.base}${appChunk.fileName}"></script>`
-    }</body>
+        ? ''
+        : `<script>__VP_HASH_MAP__ = JSON.parse(${hashMapString})</script>`
+    }
+    ${
+      appChunk
+        ? `<script type="module" async src="${siteData.base}${appChunk.fileName}"></script>`
+        : ``
+    }
+    ${inlinedScript}
+  </body>
 </html>`.trim()
   const htmlFileName = path.join(config.outDir, page.replace(/\.md$/, '.html'))
   await fs.ensureDir(path.dirname(htmlFileName))
diff --git a/src/node/config.ts b/src/node/config.ts
index 20dac3686e32..a367ac677a50 100644
--- a/src/node/config.ts
+++ b/src/node/config.ts
@@ -45,6 +45,7 @@ export interface UserConfig<ThemeConfig = any> {
 
   /**
    * Enable MPA / zero-JS mode
+   * @experimental
    */
   mpa?: boolean
 }
diff --git a/src/node/markdownToVue.ts b/src/node/markdownToVue.ts
index fc4b36c58dd5..280d4b47c293 100644
--- a/src/node/markdownToVue.ts
+++ b/src/node/markdownToVue.ts
@@ -133,6 +133,7 @@ export function createMarkdownToVueRenderFn(
 
 const scriptRE = /<\/script>/
 const scriptSetupRE = /<\s*script[^>]*\bsetup\b[^>]*/
+const scriptClientRe = /<\s*script[^>]*\bclient\b[^>]*/
 const defaultExportRE = /((?:^|\n|;)\s*)export(\s*)default/
 const namedDefaultExportRE = /((?:^|\n|;)\s*)export(.+)as(\s*)default/
 
@@ -142,7 +143,11 @@ function genPageDataCode(tags: string[], data: PageData) {
   )}`
 
   const existingScriptIndex = tags.findIndex((tag) => {
-    return scriptRE.test(tag) && !scriptSetupRE.test(tag)
+    return (
+      scriptRE.test(tag) &&
+      !scriptSetupRE.test(tag) &&
+      !scriptClientRe.test(tag)
+    )
   })
 
   if (existingScriptIndex > -1) {
diff --git a/src/node/plugin.ts b/src/node/plugin.ts
index 2da0847f0937..9c8e9f504a83 100644
--- a/src/node/plugin.ts
+++ b/src/node/plugin.ts
@@ -16,6 +16,11 @@ const staticInjectMarkerRE =
 const staticStripRE = /__VP_STATIC_START__.*?__VP_STATIC_END__/g
 const staticRestoreRE = /__VP_STATIC_(START|END)__/g
 
+// matches client-side js blocks in MPA mode.
+// in the future we may add different execution strategies like visible or
+// media queries.
+const scriptClientRE = /<script\b[^>]*client\b[^>]*>([^]*?)<\/script>/
+
 const isPageChunk = (
   chunk: OutputAsset | OutputChunk
 ): chunk is OutputChunk & { facadeModuleId: string } =>
@@ -28,7 +33,12 @@ const isPageChunk = (
 
 export function createVitePressPlugin(
   root: string,
-  {
+  siteConfig: SiteConfig,
+  ssr = false,
+  pageToHashMap?: Record<string, string>,
+  clientJSMap?: Record<string, string>
+): Plugin[] {
+  const {
     srcDir,
     configPath,
     alias,
@@ -37,10 +47,8 @@ export function createVitePressPlugin(
     vue: userVuePluginOptions,
     vite: userViteConfig,
     pages
-  }: SiteConfig,
-  ssr = false,
-  pageToHashMap?: Record<string, string>
-): Plugin[] {
+  } = siteConfig
+
   let markdownToVue: (
     src: string,
     file: string,
@@ -52,6 +60,15 @@ export function createVitePressPlugin(
     ...userVuePluginOptions
   })
 
+  const processClientJS = (code: string, id: string) => {
+    return scriptClientRE.test(code)
+      ? code.replace(scriptClientRE, (_, content) => {
+          if (ssr && clientJSMap) clientJSMap[id] = content
+          return `\n`.repeat(_.split('\n').length - 1)
+        })
+      : code
+  }
+
   let siteData = site
   let hasDeadLinks = false
   let config: ResolvedConfig
@@ -109,7 +126,9 @@ export function createVitePressPlugin(
     },
 
     transform(code, id) {
-      if (id.endsWith('.md')) {
+      if (id.endsWith('.vue')) {
+        return processClientJS(code, id)
+      } else if (id.endsWith('.md')) {
         // transform .md files into vueSrc so plugin-vue can handle it
         const { vueSrc, deadLinks, includes } = markdownToVue(
           code,
@@ -124,7 +143,7 @@ export function createVitePressPlugin(
             this.addWatchFile(i)
           })
         }
-        return vueSrc
+        return processClientJS(vueSrc, id)
       }
     },