From d4f42b3223729955122bf168e7fb3e493690d6b4 Mon Sep 17 00:00:00 2001
From: Pete Bacon Darwin <pete@bacondarwin.com>
Date: Tue, 26 Jan 2021 21:22:36 +0000
Subject: [PATCH] build(docs-infra): implement `@reviewed` tag definition
 (#40582)

The `@reviewed` tag can be used to specify the date when the
document was last reviewed.

PR Close #40582
---
 aio/src/styles/2-modules/_guides.scss         |  6 ++++++
 aio/src/styles/2-modules/_modules-dir.scss    |  1 +
 .../content-package/tag-defs/reviewed.js      | 21 +++++++++++++++++++
 .../templates/content.template.html           |  9 ++++----
 4 files changed, 33 insertions(+), 4 deletions(-)
 create mode 100644 aio/src/styles/2-modules/_guides.scss
 create mode 100644 aio/tools/transforms/content-package/tag-defs/reviewed.js

diff --git a/aio/src/styles/2-modules/_guides.scss b/aio/src/styles/2-modules/_guides.scss
new file mode 100644
index 0000000000..db656ac923
--- /dev/null
+++ b/aio/src/styles/2-modules/_guides.scss
@@ -0,0 +1,6 @@
+.reviewed {
+  color: lighten($darkgray, 10);
+  @include font-size(13);
+  font-style: italic;
+  text-align: right;
+}
\ No newline at end of file
diff --git a/aio/src/styles/2-modules/_modules-dir.scss b/aio/src/styles/2-modules/_modules-dir.scss
index d55755d566..1c48725103 100644
--- a/aio/src/styles/2-modules/_modules-dir.scss
+++ b/aio/src/styles/2-modules/_modules-dir.scss
@@ -18,6 +18,7 @@
    @import 'errors';
    @import 'features';
    @import 'filetree';
+   @import 'guides';
    @import 'heading-anchors';
    @import 'hr';
    @import 'images';
diff --git a/aio/tools/transforms/content-package/tag-defs/reviewed.js b/aio/tools/transforms/content-package/tag-defs/reviewed.js
new file mode 100644
index 0000000000..bcbe6bd18c
--- /dev/null
+++ b/aio/tools/transforms/content-package/tag-defs/reviewed.js
@@ -0,0 +1,21 @@
+/**
+ * @reviewed <date-string>
+ *
+ * Use this tag-def to indicate the date when this document was last reviewed.
+ * The date-string will be passed to the `Date()` constructor.
+ */
+module.exports = function(createDocMessage) {
+  return {
+    name: 'reviewed',
+    transforms(doc, tag, value) {
+      if (!/^\d{4}-\d{1,2}-\d{1,2}/.test(value.trim())) {
+        throw new Error(createDocMessage(
+          `Tag Error: @${tag.tagName} tag is missing the required date in the form "yyyy-mm-dd" but got "${value}"\n`,
+          doc));
+      }
+      return {
+        date: new Date(value),
+      };
+    }
+  };
+};
diff --git a/aio/tools/transforms/templates/content.template.html b/aio/tools/transforms/templates/content.template.html
index 58d0baf52d..81c975493c 100644
--- a/aio/tools/transforms/templates/content.template.html
+++ b/aio/tools/transforms/templates/content.template.html
@@ -3,12 +3,13 @@
 {% set relativePath = doc.fileInfo.relativePath %}
 {% if doc.title %}{$ ('# ' + doc.title.trim()) | marked $}{% endif %}
 {% if '/' in relativePath or 'docs.md' in relativePath %}
-  <div class="github-links">
-    {$ github.githubEditLink(doc, versionInfo) $}
-  </div>
+<div class="github-links">
+  {$ github.githubEditLink(doc, versionInfo) $}
+</div>
 {% endif %}
 {% block content %}
 <div class="content">
-{$ doc.description | marked $}
+  {$ doc.description | marked $}
+  {% if doc.reviewed %}<div class="reviewed">Last reviewed on {$ doc.reviewed.date.toDateString() $}</div>{% endif %}
 </div>
 {% endblock %}
\ No newline at end of file