fix: invalid markdown link preview

src/features/comment/CommentLinks.tsx

@@ -1,10 +1,9 @@
 import spoiler from "@aeharding/remark-lemmy-spoiler";
-import { uniqBy } from "es-toolkit";
 import { Text } from "mdast";
 import { defaultUrlTransform } from "react-markdown";
 import remarkParse from "remark-parse";
 import { unified } from "unified";
-import { SKIP, visit } from "unist-util-visit";
+import { CONTINUE, EXIT, SKIP, visit } from "unist-util-visit";
 
 import CommentLink from "#/features/post/link/CommentLink";
 import customRemarkGfm from "#/features/shared/markdown/customRemarkGfm";
@@ -45,30 +44,42 @@ export default function CommentLinks({ markdown }: CommentLinksProps) {
     const mdastTree = processor.parse(markdown);
     processor.runSync(mdastTree, markdown);
 
-    let links: LinkData[] = [];
+    const links: LinkData[] = [];
+    const urlMap = new Map<string, true>();
 
     visit(mdastTree, ["details", "link", "image"], (node) => {
       // don't show links within spoilers
       if (node.type === "details") return SKIP;
 
-      if (node.type === "link" || (!showCommentImages && node.type === "image"))
+      if (
+        node.type === "link" ||
+        (!showCommentImages && node.type === "image")
+      ) {
+        const url = parseUrl(node.url, connectedInstanceUrl)?.href;
+
+        // Skip if not a valid URL
+        if (!url) return CONTINUE;
+
+        // Skip if the URL is not a valid URL,
+        // according to default markdown link parser logic
+        if (!defaultUrlTransform(url)) return CONTINUE;
+
+        // Skip if the URL has already been added
+        if (urlMap.has(url)) return CONTINUE;
+
+        urlMap.set(url, true);
+
         links.push({
           type: node.type,
           // normalize relative links
-          url: parseUrl(node.url, connectedInstanceUrl)?.href ?? node.url,
+          url,
           text:
             "children" in node ? (node.children[0] as Text)?.value : undefined,
         });
-    });
-
-    // Dedupe by url
-    links = uniqBy(links, ({ url }) => url);
 
-    // e.g. `http://127.0.0.1:8080”`
-    links = links.filter(({ url }) => defaultUrlTransform(url));
-
-    // Max 4 links
-    links = links.slice(0, 4);
+        if (links.length === 4) return EXIT;
+      }
+    });
 
     return links.map((link, index) => <CommentLink link={link} key={index} />);
   })();