From 894e1042b02dbbeefb1f106f2a939e8cef3a62b2 Mon Sep 17 00:00:00 2001
From: Jarno Elovirta <jarno@elovirta.com>
Date: Sun, 18 Aug 2024 19:59:06 +0300
Subject: [PATCH] Add support for codeblock language prefix

Signed-off-by: Jarno Elovirta <jarno@elovirta.com>
---
 .../elovirta/dita/markdown/DitaRendererOptions.java  |  2 ++
 .../dita/markdown/renderer/TopicRenderer.java        |  2 +-
 src/main/resources/ast2markdown.xsl                  | 12 ++++++++++--
 src/test/resources/ast/codeblock.xml                 |  4 ++++
 src/test/resources/dita/codeblock.dita               |  4 ++++
 src/test/resources/hdita/codeblock.html              |  4 ++++
 src/test/resources/html/codeblock.html               |  4 ++++
 src/test/resources/markdown/codeblock.md             |  8 ++++++++
 src/test/resources/output/ast/codeblock.xml          |  4 +++-
 src/test/resources/output/markdown/codeblock.md      |  8 ++++++++
 src/test/resources/xdita/codeblock.dita              |  4 ++++
 11 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/src/main/java/com/elovirta/dita/markdown/DitaRendererOptions.java b/src/main/java/com/elovirta/dita/markdown/DitaRendererOptions.java
index f9e3c6fa..5d6c7368 100644
--- a/src/main/java/com/elovirta/dita/markdown/DitaRendererOptions.java
+++ b/src/main/java/com/elovirta/dita/markdown/DitaRendererOptions.java
@@ -6,9 +6,11 @@ public class DitaRendererOptions {
 
   public final boolean doNotRenderLinksInDocument;
   public final String noLanguageClass;
+  public final String languageClassPrefix;
 
   public DitaRendererOptions(DataHolder options) {
     doNotRenderLinksInDocument = DitaRenderer.DO_NOT_RENDER_LINKS.get(options);
     noLanguageClass = DitaRenderer.FENCED_CODE_NO_LANGUAGE_CLASS.get(options);
+    languageClassPrefix = DitaRenderer.FENCED_CODE_LANGUAGE_CLASS_PREFIX.get(options);
   }
 }
diff --git a/src/main/java/com/elovirta/dita/markdown/renderer/TopicRenderer.java b/src/main/java/com/elovirta/dita/markdown/renderer/TopicRenderer.java
index 2a6b3ce9..fb5d66c6 100644
--- a/src/main/java/com/elovirta/dita/markdown/renderer/TopicRenderer.java
+++ b/src/main/java/com/elovirta/dita/markdown/renderer/TopicRenderer.java
@@ -1293,7 +1293,7 @@ private void render(final FencedCodeBlock node, final NodeRendererContext contex
       } else {
         language = info.subSequence(0, space);
       }
-      atts.add("outputclass", /*context.getDitaOptions().languageClassPrefix +*/language.unescape());
+      atts.add("outputclass", context.getDitaOptions().languageClassPrefix + language.unescape());
     } else {
       String noLanguageClass = context.getDitaOptions().noLanguageClass.trim();
       if (!noLanguageClass.isEmpty()) {
diff --git a/src/main/resources/ast2markdown.xsl b/src/main/resources/ast2markdown.xsl
index 36c3e2e6..36ef9975 100644
--- a/src/main/resources/ast2markdown.xsl
+++ b/src/main/resources/ast2markdown.xsl
@@ -121,13 +121,21 @@
     </xsl:apply-templates>
   </xsl:template>
 
+  <xsl:variable name="codeblock-languge-prefix" as="xs:string?" select="'language-'"/>
+
   <xsl:template match="codeblock" mode="ast">
     <xsl:param name="indent" tunnel="yes" as="xs:string" select="''"/>
+
+    <xsl:variable name="classes" select="tokenize(normalize-space(@class), '\s+')" as="xs:string*"/>
+
     <xsl:value-of select="$indent"/>
     <xsl:text>```</xsl:text>
     <xsl:choose>
-      <xsl:when test="empty(@id) and @class and not(contains(@class, ' '))">
-        <xsl:value-of select="@class"/>
+      <xsl:when test="exists($codeblock-languge-prefix) and count($classes) eq 1 and starts-with($classes, $codeblock-languge-prefix)">
+        <xsl:value-of select="substring-after($classes, $codeblock-languge-prefix)"/>
+      </xsl:when>
+      <xsl:when test="empty(@id) and count($classes) eq 1">
+        <xsl:value-of select="$classes"/>
       </xsl:when>
       <xsl:otherwise>
         <xsl:call-template name="ast-attibutes"/>
diff --git a/src/test/resources/ast/codeblock.xml b/src/test/resources/ast/codeblock.xml
index 97829669..66169811 100644
--- a/src/test/resources/ast/codeblock.xml
+++ b/src/test/resources/ast/codeblock.xml
@@ -11,6 +11,10 @@
       <para>Fenced block:</para>
       <codeblock xml:space="preserve" class="scala" id="codeblock__foreach-example">items.foreach(println)
 </codeblock>
+      <para>Syntax highlighting:</para>
+      <codeblock xml:space="preserve" class="language-js">function add(a, b) {
+  return a + b;
+}</codeblock>
     </div>
   </div>
 </pandoc>
diff --git a/src/test/resources/dita/codeblock.dita b/src/test/resources/dita/codeblock.dita
index 06254936..4a64d601 100644
--- a/src/test/resources/dita/codeblock.dita
+++ b/src/test/resources/dita/codeblock.dita
@@ -11,5 +11,9 @@
     <p class="- topic/p ">Fenced block:</p>
     <codeblock class="+ topic/pre pr-d/codeblock " id="foreach-example" outputclass="scala" xml:space="preserve">items.foreach(println)
 </codeblock>
+    <p class="- topic/p ">Syntax highlighting:</p>
+    <codeblock class="+ topic/pre pr-d/codeblock " outputclass="language-js" xml:space="preserve">function add(a, b) {
+  return a + b;
+}</codeblock>
   </body>
 </topic>
diff --git a/src/test/resources/hdita/codeblock.html b/src/test/resources/hdita/codeblock.html
index 72c527db..2fe5ad27 100644
--- a/src/test/resources/hdita/codeblock.html
+++ b/src/test/resources/hdita/codeblock.html
@@ -8,4 +8,8 @@ <h1>Codeblock </h1>
       println(i)</tt></pre>
   <p>Fenced block:</p>
   <pre id="foreach-example" class="scala"><tt>items.foreach(println)</tt></pre>
+  <p>Syntax highlighting:</p>
+  <pre class="language-js"><tt>function add(a, b) {
+  return a + b;
+}</tt></pre>
 </article>
diff --git a/src/test/resources/html/codeblock.html b/src/test/resources/html/codeblock.html
index 5ff67731..a8fdcd27 100644
--- a/src/test/resources/html/codeblock.html
+++ b/src/test/resources/html/codeblock.html
@@ -8,4 +8,8 @@ <h1>Codeblock </h1>
       println(i)</code></pre>
   <p>Fenced block:</p>
   <pre id="foreach-example" class="scala"><code>items.foreach(println)</code></pre>
+  <p>Syntax highlighting:</p>
+  <pre class="language-js"><code>function add(a, b) {
+  return a + b;
+}</code></pre>
 </article>
diff --git a/src/test/resources/markdown/codeblock.md b/src/test/resources/markdown/codeblock.md
index f6e9c769..781bbfca 100644
--- a/src/test/resources/markdown/codeblock.md
+++ b/src/test/resources/markdown/codeblock.md
@@ -10,3 +10,11 @@ Fenced block:
 ```{.scala #foreach-example}
 items.foreach(println)
 ```
+
+Syntax highlighting:
+
+```js
+function add(a, b) {
+  return a + b;
+}
+```
diff --git a/src/test/resources/output/ast/codeblock.xml b/src/test/resources/output/ast/codeblock.xml
index c96bc252..906d276f 100644
--- a/src/test/resources/output/ast/codeblock.xml
+++ b/src/test/resources/output/ast/codeblock.xml
@@ -1,4 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?><pandoc><div><header id="codeblock" level="1">Codeblock</header><div><para>Code example on <code>for</code> loop:</para><codeblock xml:space="preserve">for i in items:
     println(i)
 </codeblock><para>Fenced block:</para><codeblock class="scala" id="foreach-example" xml:space="preserve">items.foreach(println)
-</codeblock></div></div></pandoc>
\ No newline at end of file
+</codeblock><para>Syntax highlighting:</para><codeblock xml:space="preserve" class="language-js">function add(a, b) {
+  return a + b;
+}</codeblock></div></div></pandoc>
\ No newline at end of file
diff --git a/src/test/resources/output/markdown/codeblock.md b/src/test/resources/output/markdown/codeblock.md
index 2d3e30ee..96eba305 100644
--- a/src/test/resources/output/markdown/codeblock.md
+++ b/src/test/resources/output/markdown/codeblock.md
@@ -15,3 +15,11 @@ items.foreach(println)
 
 ```
 
+Syntax highlighting:
+
+```js
+function add(a, b) {
+  return a + b;
+}
+```
+
diff --git a/src/test/resources/xdita/codeblock.dita b/src/test/resources/xdita/codeblock.dita
index 6664e9b5..704efd22 100644
--- a/src/test/resources/xdita/codeblock.dita
+++ b/src/test/resources/xdita/codeblock.dita
@@ -10,5 +10,9 @@
     println(i)</tt></pre>
     <p class="- topic/p ">Fenced block:</p>
     <pre class="- topic/pre " id="foreach-example" outputclass="scala" xml:space="preserve"><tt class="+ topic/ph hi-d/tt ">items.foreach(println)</tt></pre>
+    <p class="- topic/p ">Syntax highlighting:</p>
+    <pre class="- topic/pre " outputclass="language-js" xml:space="preserve"><tt class="+ topic/ph hi-d/tt ">function add(a, b) {
+  return a + b;
+}</tt></pre>
   </body>
 </topic>