Add RSS feed for technical note updates

Signed-off-by: Richard Qin <richard.qin.x@gmail.com>

6 files changed, 47 insertions, 13 deletions

diff --git a/README.md b/README.md
index 11051c4..750c513 100644
--- a/README.md
+++ b/README.md
@@ -20,18 +20,6 @@ make clean
 
 The source repository URL, per-file Git base URL, and public email are configured once in `hugo.toml`.
 
-## Announcements
-
-Announcements are separate from journal entries and technical notes. The home page shows the latest three notices above RECENT, with the full archive at `/announcements/`. Announcements and journal entries share `/rss.xml`; RECENT continues to show only journal entries and notes.
-
-Create a notice with:
-
-```sh
-hugo new content --kind announcement announcements/your-announcement/index.md
-```
-
-Set the title and `created` publication date, keep `updated` current when editing, and write the notice in the generated Markdown file. The home page limit is configured by `params.announcementLimit` in `hugo.toml`.
-
 ## Licensing
 
 Site code and templates are licensed under `GPL-3.0-or-later`; see `COPYING`.
diff --git a/content/notes/_index.md b/content/notes/_index.md
index f7b6b8e..96be96a 100644
--- a/content/notes/_index.md
+++ b/content/notes/_index.md
@@ -2,6 +2,7 @@
 title: "NOTES"
 lang: en
 url: "/notes/"
+outputs: [HTML, RSS]
 description: "Topical documents maintained over time."
 license: CC-BY-SA-4.0
 ---
diff --git a/layouts/baseof.html b/layouts/baseof.html
index 83a567e..1aa92bb 100644
--- a/layouts/baseof.html
+++ b/layouts/baseof.html
@@ -10,6 +10,9 @@
   <meta name="description" content="{{ $description }}">
   <link rel="canonical" href="{{ .Permalink }}">
   <link rel="alternate" type="application/rss+xml" title="{{ site.Title }} Journal and Announcements" href="{{ "rss.xml" | absURL }}">
+  {{- if eq .Section "notes" }}
+  <link rel="alternate" type="application/rss+xml" title="{{ site.Params.owner }} — Notes Updates" href="{{ "notes/rss.xml" | absURL }}">
+  {{- end }}
   <link rel="stylesheet" href="{{ "style.css" | relURL }}">
   <link rel="icon" href="{{ "favicon.ico" | relURL }}" sizes="any">
 </head>
diff --git a/layouts/notes/list.html b/layouts/notes/list.html
index a8411e1..2bd8c67 100644
--- a/layouts/notes/list.html
+++ b/layouts/notes/list.html
@@ -7,6 +7,7 @@
     </header>
     {{ .Content }}
     {{- if $isNotesRoot }}
+      <p><a href="{{ "notes/rss.xml" | relURL }}">Subscribe to notes updates</a></p>
       {{- with .RegularPages.ByTitle }}
         <section aria-labelledby="standalone-title">
           <h2 id="standalone-title">STANDALONE NOTES</h2>
diff --git a/layouts/notes/list.rss.xml b/layouts/notes/list.rss.xml
new file mode 100644
index 0000000..6125ac4
--- /dev/null
+++ b/layouts/notes/list.rss.xml
@@ -0,0 +1,39 @@
+{{- $items := slice -}}
+{{- range where site.RegularPages "Section" "notes" -}}
+  {{- if not .Params.updated -}}
+    {{- errorf "Missing required updated date in %s" .File.Path -}}
+  {{- end -}}
+  {{- $sortKey := printf "%s|%s" (.Lastmod.Format "2006-01-02T15:04:05-0700") .RelPermalink -}}
+  {{- $items = $items | append (dict "page" . "sortKey" $sortKey) -}}
+{{- end -}}
+{{- $items = sort $items "sortKey" "desc" -}}
+{{ printf "<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"yes\"?>" | safeHTML }}
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>{{ site.Params.owner }} — Notes Updates</title>
+    <link>{{ .Permalink }}</link>
+    <description>New and substantially revised technical notes by {{ site.Params.owner }}.</description>
+    <atom:link href="{{ (.OutputFormats.Get "RSS").Permalink }}" rel="self" type="application/rss+xml" />
+    {{- with $items }}
+    <lastBuildDate>{{ (index . 0).page.Lastmod.Format "Mon, 02 Jan 2006 15:04:05 -0700" }}</lastBuildDate>
+    {{- end }}
+    {{- range $items }}
+      {{- $page := .page -}}
+      {{- $title := $page.Title -}}
+      {{- if $page.Params.series -}}
+        {{- $title = printf "%s — %s" $page.Parent.Title $page.Title -}}
+      {{- end -}}
+      {{- $summary := $page.Plain | strings.Truncate 200 -}}
+      {{- with $page.Params.description -}}
+        {{- $summary = . | plainify -}}
+      {{- end -}}
+    <item>
+      <title>{{ $title }}</title>
+      <link>{{ $page.Permalink }}</link>
+      <guid isPermaLink="false">{{ printf "%s#updated-%s" $page.Permalink ($page.Lastmod.Format "2006-01-02") }}</guid>
+      <pubDate>{{ $page.Lastmod.Format "Mon, 02 Jan 2006 15:04:05 -0700" }}</pubDate>
+      <description>{{ $summary }}</description>
+    </item>
+    {{- end }}
+  </channel>
+</rss>
diff --git a/layouts/partials/footer.html b/layouts/partials/footer.html
index ac89098..b7a9b98 100644
--- a/layouts/partials/footer.html
+++ b/layouts/partials/footer.html
@@ -1,6 +1,8 @@
 <footer class="site-footer">
   <nav aria-label="Site information">
-    <a href="{{ "/rss.xml" | relURL }}">rss</a>
+    <a href="{{ "/rss.xml" | relURL }}">journal &amp; announcements rss</a>
+    <span aria-hidden="true">·</span>
+    <a href="{{ "/notes/rss.xml" | relURL }}">notes rss</a>
     <span aria-hidden="true">·</span>
     <a href="{{ site.Params.sourceURL }}">source</a>
     <span aria-hidden="true">·</span>