From 8eebb8dd67ac1f7e74652ddd8c98404120fc72ac Mon Sep 17 00:00:00 2001
From: Zef Hemel <zef@zef.me>
Date: Fri, 7 Feb 2025 15:39:51 +0100
Subject: [PATCH] Expose index.extractFrontmatter as syscall

---
 plugs/index/api.ts          | 21 ++++++++++++++++++++-
 plugs/index/index.plug.yaml |  6 ++++++
 web/hooks/syscall.ts        |  2 +-
 website/API/index.md        | 22 ++++++++++++++++++++++
 4 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/plugs/index/api.ts b/plugs/index/api.ts
index b45984a4..227f6562 100644
--- a/plugs/index/api.ts
+++ b/plugs/index/api.ts
@@ -1,4 +1,8 @@
-import { datastore, system } from "@silverbulletmd/silverbullet/syscalls";
+import {
+  datastore,
+  markdown,
+  system,
+} from "@silverbulletmd/silverbullet/syscalls";
 import type {
   KV,
   KvKey,
@@ -10,6 +14,12 @@ import type { QueryProviderEvent } from "../../plug-api/types.ts";
 import { determineType, type SimpleJSONType } from "./attributes.ts";
 import { ttlCache } from "$lib/memory_cache.ts";
 import type { LuaCollectionQuery } from "$common/space_lua/query_collection.ts";
+import {
+  extractFrontmatter as extractFrontmatterFromTree,
+  type FrontMatter,
+  type FrontmatterExtractOptions,
+} from "../../plug-api/lib/frontmatter.ts";
+import { renderToText } from "@silverbulletmd/silverbullet/lib/tree";
 
 const indexKey = "idx";
 const pageKey = "ridx";
@@ -245,3 +255,12 @@ export async function discoverSources() {
     // And concatenate all the tags from the schema
     .concat(Object.keys(schema.tag));
 }
+
+export async function extractFrontmatter(
+  text: string,
+  extractOptions: FrontmatterExtractOptions = {},
+): Promise<{ frontmatter: FrontMatter; text: string }> {
+  const tree = await markdown.parseMarkdown(text);
+  const frontmatter = await extractFrontmatterFromTree(tree, extractOptions);
+  return { frontmatter, text: renderToText(tree) };
+}
diff --git a/plugs/index/index.plug.yaml b/plugs/index/index.plug.yaml
index 39e0ee8c..befc123f 100644
--- a/plugs/index/index.plug.yaml
+++ b/plugs/index/index.plug.yaml
@@ -23,6 +23,12 @@ functions:
     path: api.ts:getObjectByRef
     syscall: index.getObjectByRef
     env: server
+
+  extractFrontmatter:
+    path: api.ts:extractFrontmatter
+    syscall: index.extractFrontmatter
+
+  # Event handlers
   objectSourceProvider:
     path: api.ts:objectSourceProvider
     events:
diff --git a/web/hooks/syscall.ts b/web/hooks/syscall.ts
index bf22d58a..763ccdb0 100644
--- a/web/hooks/syscall.ts
+++ b/web/hooks/syscall.ts
@@ -32,7 +32,7 @@ export class SyscallHook implements Hook<SyscallHookT> {
         syscalls[syscallName] = (ctx, ...args) => {
           // Delegate to the system to invoke the function
           return system.syscall(ctx, "system.invokeFunction", [
-            name,
+            `${plug.manifest!.name}.${name}`,
             ...args,
           ]);
         };
diff --git a/website/API/index.md b/website/API/index.md
index daae7b32..bb92a4f5 100644
--- a/website/API/index.md
+++ b/website/API/index.md
@@ -1,3 +1,9 @@
+---
+testattribute: 10
+---
+
+#apidoc
+
 The `index` API provides functions for interacting with SilverBullet's [[Objects]], allowing you to store and query page-associated data.
 
 ## Object Operations
@@ -38,3 +44,19 @@ local task = index.getObjectByRef("my page", "mytask", "task1")
 if task then
     print("Found task: " .. task.content)
 end
+```
+
+## index.extractFrontmatter(text, extractOptions)
+Extracts frontmatter from a markdown document (whose text is provided as argument), possibly cleaning it up. It also parses top-level tags consistent with SilverBullet's tag indexing system.
+
+It returns a table with two keys:
+- `frontmatter`: A table containing the parsed frontmatter.
+- `text`: The text of the document, with any changes applied requested with the `extractOptions`.
+
+The `extractOptions` is an optional table that can contain the following keys (which will affect the returned `text`):
+- `removeKeys`: An array of keys to remove from the frontmatter.
+- `removeTags`: A boolean or array of tags to remove from the frontmatter.
+- `removeFrontmatterSection`: A boolean to remove the frontmatter section from the document.
+
+Example applied to this page:
+${(index.extractFrontmatter(editor.getText())).frontmatter}
\ No newline at end of file