Use mfm-js for MFM parsing (#7415)

* wip

* Update mfm.ts

* wip

* update mfmjs

* refactor

* nanka

* Update mfm.ts

* Update to-html.ts

* Update to-html.ts

* wip

* fix test

* fix test

src/misc/extract-url-from-mfm.ts

@@ -0,0 +1,34 @@
+import * as mfm from 'mfm-js';
+import { unique } from '@/prelude/array';
+
+// unique without hash
+// [ http://a/#1, http://a/#2, http://b/#3 ] => [ http://a/#1, http://b/#3 ]
+const removeHash = (x: string) => x.replace(/#[^#]*$/, '');
+
+export function extractUrlFromMfm(nodes: mfm.MfmNode[], respectSilentFlag = true): string[] {
+	const urlNodes = [] as (mfm.MfmUrl | mfm.MfmLink)[];
+
+	function scan(nodes: mfm.MfmNode[]) {
+		for (const node of nodes) {
+			if (node.type === 'url') {
+				urlNodes.push(node);
+			} else if (node.type === 'link') {
+				if (!respectSilentFlag || !node.props.silent) {
+					urlNodes.push(node);
+				}
+			} else if (node.children) {
+				scan(node.children);
+			}
+		}
+	}
+
+	scan(nodes);
+
+	const urls = unique(urlNodes.map(x => x.props.url));
+
+	return urls.reduce((array, url) => {
+		const removed = removeHash(url);
+		if (!array.map(x => removeHash(x)).includes(removed)) array.push(url);
+		return array;
+	}, [] as string[]);
+}