Unfurl card in link previews

src/note.ts

@@ -6,16 +6,6 @@ linkify.registerCustomProtocol('wss');
 
 const url = (path: string) => new URL(path, LOCAL_DOMAIN).toString();
 
-/** Get pubkey from decoded bech32 entity, or undefined if not applicable. */
-function getDecodedPubkey(decoded: nip19.DecodeResult): string | undefined {
-  switch (decoded.type) {
-    case 'npub':
-      return decoded.data;
-    case 'nprofile':
-      return decoded.data.pubkey;
-  }
-}
-
 const linkifyOpts: linkify.Opts = {
   render: {
     hashtag: ({ content }) => {
@@ -46,16 +36,8 @@ type Link = ReturnType<typeof linkify.find>[0];
 interface ParsedNoteContent {
   html: string;
   links: Link[];
-}
-
-/** Ensures the URL can be parsed. Why linkifyjs doesn't already guarantee this, idk... */
-function isValidLink(link: Link): boolean {
-  try {
-    new URL(link.href);
-    return true;
-  } catch (_e) {
-    return false;
-  }
+  /** First non-media URL - eligible for a preview card. */
+  firstUrl: string | undefined;
 }
 
 /** Convert Nostr content to Mastodon API HTML. Also return parsed data. */
@@ -63,10 +45,12 @@ function parseNoteContent(content: string): ParsedNoteContent {
   // Parsing twice is ineffecient, but I don't know how to do only once.
   const html = linkifyStr(content, linkifyOpts);
   const links = linkify.find(content).filter(isValidLink);
+  const firstUrl = links.find(isNonMediaLink)?.href;
 
   return {
     html,
     links,
+    firstUrl,
   };
 }
 
@@ -77,9 +61,7 @@ interface MediaLink {
 
 function getMediaLinks(links: Link[]): MediaLink[] {
   return links.reduce<MediaLink[]>((acc, link) => {
-    const { pathname } = new URL(link.href);
-    const mimeType = mime.getType(pathname);
-
+    const mimeType = getUrlMimeType(link.href);
     if (!mimeType) return acc;
 
     const [baseType, _subType] = mimeType.split('/');
@@ -95,4 +77,39 @@ function getMediaLinks(links: Link[]): MediaLink[] {
   }, []);
 }
 
+function isNonMediaLink({ href }: Link): boolean {
+  return /^https?:\/\//.test(href) && !getUrlMimeType(href);
+}
+
+/** Ensures the URL can be parsed. Why linkifyjs doesn't already guarantee this, idk... */
+function isValidLink(link: Link): boolean {
+  try {
+    new URL(link.href);
+    return true;
+  } catch (_e) {
+    console.error(`Invalid link: ${link.href}`);
+    return false;
+  }
+}
+
+/** `npm:mime` treats `.com` as a file extension, so parse the full URL to get its path first. */
+function getUrlMimeType(url: string): string | undefined {
+  try {
+    const { pathname } = new URL(url);
+    return mime.getType(pathname) || undefined;
+  } catch (_e) {
+    return undefined;
+  }
+}
+
+/** Get pubkey from decoded bech32 entity, or undefined if not applicable. */
+function getDecodedPubkey(decoded: nip19.DecodeResult): string | undefined {
+  switch (decoded.type) {
+    case 'npub':
+      return decoded.data;
+    case 'nprofile':
+      return decoded.data.pubkey;
+  }
+}
+
 export { getMediaLinks, type MediaLink, parseNoteContent };