From 2844c8bc25e4b36b64a68bc42a0227462bd4785d Mon Sep 17 00:00:00 2001
From: Zef Hemel <zef@zef.me>
Date: Thu, 2 Nov 2023 12:35:30 +0100
Subject: [PATCH] Markdown plug APIS

---
 plugs/markdown/api.ts             | 66 +++++++++++++++++++++++++++++++
 plugs/markdown/markdown.plug.yaml |  5 ++-
 plugs/markdown/markdown_render.ts |  2 +-
 3 files changed, 71 insertions(+), 2 deletions(-)
 create mode 100644 plugs/markdown/api.ts

diff --git a/plugs/markdown/api.ts b/plugs/markdown/api.ts
new file mode 100644
index 00000000..7f7fb449
--- /dev/null
+++ b/plugs/markdown/api.ts
@@ -0,0 +1,66 @@
+import {
+  findNodeOfType,
+  ParseTree,
+  renderToText,
+  replaceNodesMatchingAsync,
+} from "$sb/lib/tree.ts";
+import { codeWidget } from "$sb/syscalls.ts";
+import { parseMarkdown } from "$sb/silverbullet-syscall/markdown.ts";
+import {
+  MarkdownRenderOptions,
+  renderMarkdownToHtml,
+} from "./markdown_render.ts";
+
+/**
+ * Finds code widgets, runs their plug code to render and inlines their content in the parse tree
+ * @param mdTree parsed markdown tree
+ * @param pageName name of the current page
+ * @returns modified mdTree
+ */
+export async function expandCodeWidgets(
+  mdTree: ParseTree,
+  pageName: string,
+): Promise<ParseTree> {
+  await replaceNodesMatchingAsync(mdTree, async (n) => {
+    if (n.type === "FencedCode") {
+      const codeInfo = findNodeOfType(n, "CodeInfo");
+      if (!codeInfo) {
+        return;
+      }
+      const codeType = codeInfo.children![0].text!;
+      const codeTextNode = findNodeOfType(n, "CodeText");
+      try {
+        // This will error out if this is not a code wiget, which is fine
+        const result = await codeWidget.render(
+          codeType,
+          renderToText(codeTextNode!),
+          pageName,
+        );
+        // Only do this for "markdown" widgets, that is: that can render to markdown
+        if (result.markdown) {
+          const parsedBody = await parseMarkdown(result.markdown);
+          // Recursively process
+          return expandCodeWidgets(
+            parsedBody,
+            pageName,
+          );
+        }
+      } catch (e: any) {
+        // 'not found' is to be expected (no code widget configured for this language)
+        // Every other error should probably be reported
+        if (!e.message.includes("not found")) {
+          console.error("Error rendering code", e.message);
+        }
+      }
+    }
+  });
+  return mdTree;
+}
+
+export async function markdownToHtml(
+  markdown: string,
+  options: MarkdownRenderOptions = {},
+) {
+  const mdTree = await parseMarkdown(markdown);
+  return renderMarkdownToHtml(mdTree, options);
+}
diff --git a/plugs/markdown/markdown.plug.yaml b/plugs/markdown/markdown.plug.yaml
index b7178963..b9cfeb53 100644
--- a/plugs/markdown/markdown.plug.yaml
+++ b/plugs/markdown/markdown.plug.yaml
@@ -2,10 +2,13 @@ name: markdown
 assets:
   - "assets/*"
 functions:
-
   # API
   markdownContentWidget:
     path: markdown_content_widget.ts:markdownContentWidget
+  expandCodeWidgets:
+    path: api.ts:expandCodeWidgets
+  markdownToHtml:
+    path: api.ts:markdownToHtml
 
   # User facing
 
diff --git a/plugs/markdown/markdown_render.ts b/plugs/markdown/markdown_render.ts
index 2095ab85..2d8d6e44 100644
--- a/plugs/markdown/markdown_render.ts
+++ b/plugs/markdown/markdown_render.ts
@@ -8,7 +8,7 @@ import {
 } from "$sb/lib/tree.ts";
 import { Fragment, renderHtml, Tag } from "./html_render.ts";
 
-type MarkdownRenderOptions = {
+export type MarkdownRenderOptions = {
   failOnUnknown?: true;
   smartHardBreak?: true;
   annotationPositions?: true;