refactoring

Resolve #7779

packages/backend/src/misc/extract-custom-emojis-from-mfm.ts

@@ -0,0 +1,10 @@
+import * as mfm from 'mfm-js';
+import { unique } from '@/prelude/array';
+
+export function extractCustomEmojisFromMfm(nodes: mfm.MfmNode[]): string[] {
+	const emojiNodes = mfm.extract(nodes, (node) => {
+		return (node.type === 'emojiCode' && node.props.name.length <= 100);
+	});
+
+	return unique(emojiNodes.map(x => x.props.name));
+}