From 2b4b80061818f1c471aafb23c0572172ef842138 Mon Sep 17 00:00:00 2001
From: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>
Date: Wed, 20 Jul 2022 14:31:07 +0530
Subject: [PATCH] feat: provide `transformHtml` hook (#1022)

---
 src/node/build/render.ts | 11 ++++++++++-
 src/node/config.ts       | 24 ++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/node/build/render.ts b/src/node/build/render.ts
index a03729e5f421..c38af2a3a216 100644
--- a/src/node/build/render.ts
+++ b/src/node/build/render.ts
@@ -173,7 +173,16 @@ export async function renderPage(
 </html>`.trim()
   const htmlFileName = path.join(config.outDir, page.replace(/\.md$/, '.html'))
   await fs.ensureDir(path.dirname(htmlFileName))
-  await fs.writeFile(htmlFileName, html)
+  const transformedHtml = await config.transformHtml?.(html, htmlFileName, {
+    siteConfig: config,
+    siteData,
+    pageData,
+    title,
+    description,
+    head,
+    content
+  })
+  await fs.writeFile(htmlFileName, transformedHtml || html)
 }
 
 function resolvePageImports(
diff --git a/src/node/config.ts b/src/node/config.ts
index 1fac1d1b083a..28ecdec87af8 100644
--- a/src/node/config.ts
+++ b/src/node/config.ts
@@ -16,7 +16,8 @@ import {
   LocaleConfig,
   DefaultTheme,
   APPEARANCE_KEY,
-  createLangDictionary
+  createLangDictionary,
+  PageData
 } from './shared'
 import { resolveAliases, DEFAULT_THEME_PATH } from './alias'
 import { MarkdownOptions } from './markdown/markdown'
@@ -77,6 +78,23 @@ export interface UserConfig<ThemeConfig = any> {
    * @param siteConfig The resolved configuration.
    */
   buildEnd?: (siteConfig: SiteConfig) => Promise<void>
+
+  /**
+   * HTML transform hook: runs before writing HTML to dist.
+   */
+  transformHtml?: (
+    code: string,
+    id: string,
+    ctx: {
+      siteConfig: SiteConfig
+      siteData: SiteData
+      pageData: PageData
+      title: string
+      description: string
+      head: HeadConfig[]
+      content: string
+    }
+  ) => Promise<string | void>
 }
 
 export type RawConfigExports<ThemeConfig = any> =
@@ -95,6 +113,7 @@ export interface SiteConfig<ThemeConfig = any>
     | 'lastUpdated'
     | 'ignoreDeadLinks'
     | 'buildEnd'
+    | 'transformHtml'
   > {
   root: string
   srcDir: string
@@ -174,7 +193,8 @@ export async function resolveConfig(
     shouldPreload: userConfig.shouldPreload,
     mpa: !!userConfig.mpa,
     ignoreDeadLinks: userConfig.ignoreDeadLinks,
-    buildEnd: userConfig.buildEnd
+    buildEnd: userConfig.buildEnd,
+    transformHtml: userConfig.transformHtml
   }
 
   return config