generate rss channel as xml str

lib/main.typ

@@ -2,6 +2,7 @@
 #import "./html_body.typ": html_body
 #import "./html_utils.typ": html_show
 #import "./summary.typ": summary, card-list
+#import "./rss.typ": rss
 
 
 /// Mail template function

lib/rss.typ

@@ -0,0 +1,81 @@
+#import "./summary.typ": summary-sort-key
+
+// TODO DOCUMENT
+
+#let xml-tag(
+  name,
+  attrs: (),
+  children: none,
+  body: none,
+) = {
+  assert(not ((children != none) and (body != none)), message: "children and body cannot be set at the same time")
+
+  ("<" + name 
+    + if attrs.len() != 0 { " " } else { "" } 
+    + attrs.map(attr => attr.at(0) + "=\"" + attr.at(1) + "\"").join(" ") 
+  + if children == none and body == none { "/>" } else if children != none { 
+    (
+      ">\n  " + children.join("\n").replace("\n", "\n  ") + 
+      "\n</" + name + ">"
+    )
+  } else if body != none {
+    ">" + body + "</" + name + ">"
+  } else {
+    panic("children and body cannot be set at the same time")
+  })
+}
+
+// We don't care about the hour, but RFC 822 requires it, so use 0 and GMT
+#let date-format-rfc822 = "[day padding:zero] [month repr:short] [year repr:full] 00:00:01 +0000"
+
+#let rss(
+  title,
+  link,
+  description,
+  rss-url,
+  summaries,
+  language: "en-us",
+  managing-editor: none,
+  webmaster: none,
+) = {
+  let channel-element = (
+    xml-tag("title", body: title),
+    xml-tag("link", body: link),
+    xml-tag("description", body: description),
+    xml-tag("language", body: language),
+    xml-tag("lastBuildDate", body: datetime.today().display(date-format-rfc822)),
+    xml-tag("docs", body: "https://www.rssboard.org/rss-specification"),
+    xml-tag("generator", body: "Some random Typst scrypt"),
+    xml-tag("atom:link", attrs: (
+      ("href", rss-url),
+      ("rel", "self"),
+      ("type", "application/rss+xml")
+    )),
+  )
+  if managing-editor != none {
+    channel-element.push(xml-tag("managingEditor", body: managing-editor))
+  }
+  if webmaster != none {
+    channel-element.push(xml-tag("webMaster", body: webmaster))
+  }
+  let items = summaries.sorted(
+    key: summary-sort-key
+  ).map(it => xml-tag(
+    "item",
+    children: (
+      xml-tag("title", body: it.document-args.title),
+      xml-tag("link", body: it.template-args.url),
+      xml-tag("guid", body: it.template-args.url),
+      xml-tag("description", body: it.document-args.description),
+      xml-tag("pubDate", body: it.document-args.date.display(date-format-rfc822)),
+    ) + it.template-args.tags.map(tag => xml-tag("category", body: tag))
+  ))
+  xml-tag(
+    "rss", 
+    attrs: (
+      ("xmlns:atom", "http://www.w3.org/2005/Atom"), 
+      ("version","2.0")
+    ), 
+    children: (xml-tag("channel", children: channel-element + items),)
+  )
+}

lib/summary.typ

@@ -146,6 +146,13 @@
   return summ
 }
 
+#let summary-sort-key(summ) = -(
+  summ.document-args.date.day()-1 + 31 * (
+    (summ.document-args.date.month()-1) + 
+    12 * summ.document-args.date.year()
+  )
+)
+
 /// Display a list of summary cards.
 ///
 /// min-width is the minimum width of the cards, in px.
@@ -166,12 +173,7 @@
     lang: "raw-css",
   )
   chtml.summary-card-list(attrs: (class: class-name), {
-    for summ in summs.sorted(key: it => 
-      -(it.document-args.date.day()-1 + 31 * (
-        (it.document-args.date.month()-1) + 
-        12 * it.document-args.date.year()
-      ))
-    ) {
+    for summ in summs.sorted(key: summary-sort-key) {
       summ.card
     }
   })

test_template/main.typ

@@ -166,11 +166,9 @@ thead {
 )
 
 #let perm = (17, 6, 20, 19, 15, 5, 13, 11, 14, 12, 16, 10, 2, 3, 1, 9, 7, 4, 18, 8)
-#card-list(
-  min-width: 200,
-  range(20).map(i => 
+#let summaries = range(20).map(i => 
   summary(
-      url: "http://test.example.com",
+    url: "http://test.example.com/tst/" + str(perm.at(i)),
     title: "Card " + str(perm.at(i)),
     tags: if perm.at(i) == 20 {
       ("tag2", "tag5","loooooonnnnnnnnnnnnnng-tag","some-tag","some-other-tag")
@@ -184,4 +182,16 @@ thead {
     date: datetime(year: 2000, month: 12, day: perm.at(i)),
   )
 )
+#card-list(
+  min-width: 200,
+  summaries,
 )
+
+#raw(lang: "xml", block: true, rss(
+  "TeTyTe test typst template",
+  "https://test.example.com",
+  "Test of the TTT template",
+  "https://test.example.com/rss.xml",
+  summaries,
+  webmaster: "me@example.com (Me)",
+))