From c3897e1d50d015b9c460db7c8635357137819bd4 Mon Sep 17 00:00:00 2001
From: Peter Bengtsson <peterbe@github.com>
Date: Mon, 17 Jun 2024 17:05:25 -0400
Subject: [PATCH] Port `context/layout.js` to TypeScript (#51241)

---
 src/frame/middleware/context/layout.js | 20 --------------------
 src/frame/middleware/context/layout.ts | 24 ++++++++++++++++++++++++
 src/frame/middleware/index.ts          |  2 +-
 src/types.ts                           |  2 ++
 4 files changed, 27 insertions(+), 21 deletions(-)
 delete mode 100644 src/frame/middleware/context/layout.js
 create mode 100644 src/frame/middleware/context/layout.ts

diff --git a/src/frame/middleware/context/layout.js b/src/frame/middleware/context/layout.js
deleted file mode 100644
index c0cda4a35d5a..000000000000
--- a/src/frame/middleware/context/layout.js
+++ /dev/null
@@ -1,20 +0,0 @@
-export default function layoutContext(req, res, next) {
-  if (!req.context.page) return next()
-
-  const layoutOptsByType = {
-    // Layouts can be specified with a `layout` frontmatter value.
-    // Any invalid layout values will be caught by frontmatter schema validation.
-    string: req.context.page.layout,
-    // A `layout: false` value means use no layout.
-    boolean: '',
-    // For all other files (like articles and the homepage), use the `default` layout.
-    undefined: 'default',
-  }
-
-  const layoutName = layoutOptsByType[typeof req.context.page.layout]
-
-  // Attach to the context object
-  req.context.currentLayoutName = layoutName
-
-  return next()
-}
diff --git a/src/frame/middleware/context/layout.ts b/src/frame/middleware/context/layout.ts
new file mode 100644
index 000000000000..447955cc8917
--- /dev/null
+++ b/src/frame/middleware/context/layout.ts
@@ -0,0 +1,24 @@
+import type { Response, NextFunction } from 'express'
+
+import type { ExtendedRequest } from '@/types'
+
+export default function layoutContext(req: ExtendedRequest, res: Response, next: NextFunction) {
+  if (!req.context) throw new Error('request is not contextualized')
+  if (!req.context.page) return next()
+
+  let layoutName = 'default'
+  if (req.context.page.layout) {
+    if (typeof req.context.page.layout === 'boolean') {
+      // A `layout: false` value means use no layout.
+      layoutName = ''
+    } else if (typeof req.context.page.layout === 'string') {
+      layoutName = req.context.page.layout
+    } else {
+      throw new Error(`Invalid layout value type: ${req.context.page.layout}`)
+    }
+  }
+
+  req.context.currentLayoutName = layoutName
+
+  return next()
+}
diff --git a/src/frame/middleware/index.ts b/src/frame/middleware/index.ts
index 58272f3b19ad..336187516933 100644
--- a/src/frame/middleware/index.ts
+++ b/src/frame/middleware/index.ts
@@ -39,7 +39,7 @@ import triggerError from '@/observability/middleware/trigger-error'
 import secretScanning from '@/secret-scanning/middleware/secret-scanning'
 import ghesReleaseNotes from '@/release-notes/middleware/ghes-release-notes'
 import whatsNewChangelog from './context/whats-new-changelog'
-import layout from './context/layout.js'
+import layout from './context/layout'
 import currentProductTree from './context/current-product-tree.js'
 import genericToc from './context/generic-toc.js'
 import breadcrumbs from './context/breadcrumbs.js'
diff --git a/src/types.ts b/src/types.ts
index ca839791c884..29271a80f6b4 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -82,6 +82,7 @@ export type Context = {
   autotitleLanguage?: string
   latestPatch?: string
   latestRelease?: string
+  currentLayoutName?: string
 }
 
 export type GHESRelease = {
@@ -185,6 +186,7 @@ export type Page = {
   versions: FrontmatterVersions
   applicableVersions: string[]
   changelog?: ChangeLog
+  layout?: string | boolean
 }
 
 type ChangeLog = {