From a26588835b8e2752e1d1a9480280d34217bb782e Mon Sep 17 00:00:00 2001
From: James Brumond <james@jbrumond.me>
Date: Sat, 29 Apr 2023 17:19:34 -0700
Subject: [PATCH] support for stripping off frontmatter

---
 bin/strip-frontmatter        |  2 ++
 bin/strip-frontmatter.js     |  2 ++
 readme.md                    | 38 ++++++++++++++++++++++++++++++++++++
 src/bin/strip-frontmatter.ts |  2 ++
 src/frontmatter.ts           | 18 +++++++++++++++++
 src/index.ts                 |  3 ++-
 6 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 bin/strip-frontmatter
 create mode 100644 bin/strip-frontmatter.js
 create mode 100644 src/bin/strip-frontmatter.ts
 create mode 100644 src/frontmatter.ts

diff --git a/bin/strip-frontmatter b/bin/strip-frontmatter
new file mode 100644
index 0000000..f17b3fb
--- /dev/null
+++ b/bin/strip-frontmatter
@@ -0,0 +1,2 @@
+#!/bin/sh
+node $(dirname $0)/strip-frontmatter.js $*
\ No newline at end of file
diff --git a/bin/strip-frontmatter.js b/bin/strip-frontmatter.js
new file mode 100644
index 0000000..62e7212
--- /dev/null
+++ b/bin/strip-frontmatter.js
@@ -0,0 +1,2 @@
+#!/usr/bin/env node
+require('../build/bin/strip-frontmatter.js');
\ No newline at end of file
diff --git a/readme.md b/readme.md
index 10b50a1..a124be7 100644
--- a/readme.md
+++ b/readme.md
@@ -38,6 +38,28 @@ async function main() {
 }
 ```
 
+### Handling Frontmatter
+
+```ts
+import { process_frontmatter } from './build';
+
+const raw_content = `---
+title: Example Markdown with Frontmatter
+foo:
+- bar
+- baz
+---
+
+# This is some markdown
+`;
+
+const { frontmatter, markdown } = process_frontmatter(raw_content);
+
+console.log(frontmatter.title);  // "Example Markdown with Frontmatter"
+console.log(frontmatter.foo);    // [ "bar", "baz" ]
+console.log(markdown);           // "\n# This is some markdown\n"
+```
+
 
 
 ## Command Line Use
@@ -46,6 +68,22 @@ async function main() {
 echo '# This is some markdown' | ./bin/markdown2html --base-url 'https://example.com' > output.html
 ```
 
+### Handling Frontmatter
+
+```bash
+filecontents="---
+title: Example Markdown with Frontmatter
+foo:
+- bar
+- baz
+---
+
+# This is some markdown
+"
+
+echo "$filecontents" | ./bin/strip-frontmatter frontmatter.json > markdown.md
+```
+
 
 
 ## Options
diff --git a/src/bin/strip-frontmatter.ts b/src/bin/strip-frontmatter.ts
new file mode 100644
index 0000000..00d300d
--- /dev/null
+++ b/src/bin/strip-frontmatter.ts
@@ -0,0 +1,2 @@
+
+console.log('strip-frontmatter');
diff --git a/src/frontmatter.ts b/src/frontmatter.ts
new file mode 100644
index 0000000..1e49651
--- /dev/null
+++ b/src/frontmatter.ts
@@ -0,0 +1,18 @@
+
+import * as yaml from 'yaml';
+
+export function process_frontmatter(document: string) {
+	if (! document.startsWith('---\n')) {
+		return {
+			frontmatter: null,
+			markdown: document,
+		};
+	}
+
+	const endIndex = document.slice(3).indexOf('\n---\n') + 3;
+	const frontmatterYaml = document.slice(3, endIndex);
+	const markdown = document.slice(endIndex + 4);
+	const frontmatter = yaml.parse(frontmatterYaml);
+
+	return { frontmatter, markdown };
+}
diff --git a/src/index.ts b/src/index.ts
index 8ecc5ae..a30d753 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,2 +1,3 @@
 
-export * from './render';
+export { process_frontmatter } from './frontmatter';
+export { render_markdown_to_html, MarkdownExtension, MarkdownOptions } from './render';