render descriptions on channel page with Markdown syntax

CHANGELOG.md

@@ -10,6 +10,8 @@
 - improved error message if channel-build fails randomly in case old files could not be removed (#6)
 - improved `sc4pac` bash script to allow symlinking into path on Linux/macOS
 - The progress spinner animation was switched to ASCII symbols for compatibility with non-Unicode fonts in some terminals.
+- The metadata text fields like `description` etc. are now rendered as Markdown.
+  For correct text wrapping, multiline text blocks should start with `|` instead of `>`, from now on.
 
 
 ## [0.4.5] - 2024-10-17

channel-testing/yaml/templates/package-template-basic.yaml

@@ -52,15 +52,23 @@ assets:  # Optional list of assets from which to extract files (zero or more)
 # Additional descriptive information, entirely optional.
 info:
   summary: "One-line summary"
-  warning: >
+  warning: |
     Special instructions to display before installation, such as bulldozing requirements.
   conflicts: "Notes about incompatibilities"
-  description: >
+  description: |
     Longer text with some details.
 
     Yet more text…
 
-    Use syntax `pkg=group:name` to reference packages in description text.
+    Use the syntax `pkg=group:name` to reference packages in description text.
+
+    ### Markdown
+
+    Common **Markdown** syntaxes like *emphasis*, [URLs](https://memo33.github.io/sc4pac/)
+    or lists are supported:
+    - one
+    - two
+    - three
   author: ""  # original author of the content, if useful
   images: [ "img1.png", "img2.png" ]
   website: "example.org"

web/channel/index-dev.html

@@ -17,6 +17,8 @@
         </li>
       </ul>
     </nav>
+    <script src="https://cdn.jsdelivr.net/npm/dompurify/dist/purify.min.js"></script>
+    <script src="https://cdn.jsdelivr.net/npm/marked/lib/marked.umd.min.js"></script>
     <script type="text/javascript" src="../target/scala-3.4.2/sc4pac-web-fastopt/main.js"></script>
   </body>
 </html>

web/channel/index.html

@@ -17,6 +17,8 @@
         </li>
       </ul>
     </nav>
+    <script src="https://cdn.jsdelivr.net/npm/dompurify/dist/purify.min.js"></script>
+    <script src="https://cdn.jsdelivr.net/npm/marked/lib/marked.umd.min.js"></script>
     <script type="text/javascript" src="main.js"></script>
   </body>
 </html>

web/src/main/scala/sc4pac/web/ChannelPage.scala

@@ -36,6 +36,26 @@ object JsonData extends SharedData {
     parseModule(_).left.map(e => throw new IllegalArgumentException(e)).merge)
 }
 
+@js.native
+@js.annotation.JSGlobal
+object DOMPurify extends js.Object {
+  def sanitize(text: String): String = js.native
+}
+
+@js.native
+@js.annotation.JSGlobal("marked")
+object Marked extends js.Object {
+  def parse(text: String): String = js.native
+  def use(extensions: js.Any*): Unit = js.native
+}
+
+@js.native
+trait TokensCodespan extends js.Object {  // see https://github.com/markedjs/marked/blob/7e4e3435eaca2b0f48f5aedb53d67a36170086f3/src/Tokens.ts#L57
+  val `type`: String  // "codespan"
+  val raw: String  // with quotes
+  val text: String  // without quotes
+}
+
 object ChannelPage {
 
   // val channelUrl = "http://localhost:8090/channel/"
@@ -88,38 +108,32 @@ object ChannelPage {
     else H.code(module.orgName)
 
   /** Highlights syntax `pkg=group:name` in metadata description text. */
-  def applyMarkdownPkg(line: String): H.Frag = {
-    val builder = Seq.newBuilder[H.Frag]
-    var idx = 0
-    for (m <- BareModule.pkgMarkdownRegex.findAllMatchIn(line)) {
-      if (idx < m.start) {
-        builder += line.substring(idx, m.start)
-      }
-      builder += pkgNameFrag(BareModule(Organization(m.group(1)), ModuleName(m.group(2))), link = true)
-      idx = m.end
-    }
-    if (idx < line.length) {
-      builder += line.substring(idx, line.length)
-    }
-    builder.result()
+  def renderCodespan(codespan: TokensCodespan): String = codespan.raw match
+    case BareModule.pkgMarkdownRegex(group, name) =>
+      val module = BareModule(Organization(group), ModuleName(name))
+      // a raw re-implementation of pkgNameFrag
+      s"""<code class="code-left">${module.group.value}:</code><a href="?pkg=${module.orgName}"><code class="code-right">${module.name.value}</code></a>"""
+    case _ => s"<code>${codespan.text}</code>"
+
+  def markdownFrag(text: String): H.Frag = {
+    H.raw(DOMPurify.sanitize(Marked.parse(text)))
   }
 
   def pkgInfoFrag(pkg: JsonData.Package) = {
     val module = pkg.toBareDep
     val b = Seq.newBuilder[H.Frag]
     def add(label: String, child: H.Frag): Unit =
       b += H.tr(H.th(label), H.td(child))
-    def mkPar(text: String) = text.trim.linesIterator.map(line => H.p(applyMarkdownPkg(line))).toSeq
 
     // add("Name", pkg.name)
     // add("Group", pkg.group)
     add("Version", pkg.version)
-    add("Summary", if (pkg.info.summary.nonEmpty) applyMarkdownPkg(pkg.info.summary) else "-")
+    add("Summary", if (pkg.info.summary.nonEmpty) markdownFrag(pkg.info.summary) else "-")
     if (pkg.info.description.nonEmpty)
-      add("Description", mkPar(pkg.info.description))
+      add("Description", markdownFrag(pkg.info.description))
     if (pkg.info.warning.nonEmpty)
-      add("Warning", mkPar(pkg.info.warning))
-    add("Conflicts", if (pkg.info.conflicts.isEmpty) "None" else mkPar(pkg.info.conflicts))
+      add("Warning", markdownFrag(pkg.info.warning))
+    add("Conflicts", if (pkg.info.conflicts.isEmpty) "None" else markdownFrag(pkg.info.conflicts))
     if (pkg.info.author.nonEmpty)
       add("Author", pkg.info.author)
     if (pkg.info.website.nonEmpty) {
@@ -193,7 +207,7 @@ object ChannelPage {
       H.table(H.id := "channelcontents")(H.tbody(items.flatMap { item =>
         if (displayCategory2.isEmpty || item.category == displayCategory2) {  // either show all or filter by category
           item.toBareDep match
-            case mod: BareModule => Some(H.tr(H.td(pkgNameFrag(mod, link = true)), H.td(applyMarkdownPkg(item.summary))))
+            case mod: BareModule => Some(H.tr(H.td(pkgNameFrag(mod, link = true)), H.td(markdownFrag(item.summary))))
             case _: BareAsset => None
         } else {
           None
@@ -203,6 +217,7 @@ object ChannelPage {
   }
 
   def setupUI(): Unit = {
+    Marked.use(js.Dictionary("renderer" -> js.Dictionary("codespan" -> (renderCodespan: js.Function))))
     val urlParams = new dom.URLSearchParams(dom.window.location.search)
     val pkgName = urlParams.get("pkg")
     if (pkgName == null) {