From f898627172bc6140e25dd330ff23fd6da9b7055b Mon Sep 17 00:00:00 2001
From: Hilary Torn <hilary.torn@gmail.com>
Date: Wed, 26 Nov 2025 19:38:24 +0200
Subject: [PATCH] feat(bluesky): add external embed cards for URL previews

Adds support for app.bsky.embed.external when posting to Bluesky with URLs
but no media attachments. Fetches Open Graph metadata (title, description,
thumbnail) and creates rich link preview cards.

Closes #667
---
 .../integrations/social/bluesky.provider.ts   | 128 ++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/libraries/nestjs-libraries/src/integrations/social/bluesky.provider.ts b/libraries/nestjs-libraries/src/integrations/social/bluesky.provider.ts
index 3e1aa59bd..b9346b35b 100644
--- a/libraries/nestjs-libraries/src/integrations/social/bluesky.provider.ts
+++ b/libraries/nestjs-libraries/src/integrations/social/bluesky.provider.ts
@@ -17,6 +17,7 @@ import {
   AppBskyVideoDefs,
   AtpAgent,
   BlobRef,
+  AppBskyEmbedExternal,
 } from '@atproto/api';
 import dayjs from 'dayjs';
 import { Integration } from '@prisma/client';
@@ -61,6 +62,124 @@ async function reduceImageBySize(url: string, maxSizeKB = 976) {
   }
 }
 
+interface OpenGraphData {
+  title: string;
+  description: string;
+  image?: string;
+}
+
+async function fetchOpenGraphData(url: string): Promise<OpenGraphData | null> {
+  try {
+    const response = await axios.get(url, {
+      timeout: 10000,
+      headers: {
+        'User-Agent': 'Mozilla/5.0 (compatible; Postiz/1.0; +https://postiz.com)',
+        'Accept': 'text/html,application/xhtml+xml',
+      },
+      maxRedirects: 5,
+    });
+
+    const html = response.data as string;
+
+    // Extract Open Graph tags or fallback to standard meta tags
+    const getMetaContent = (property: string): string | undefined => {
+      // Try og: tags first
+      const ogMatch = html.match(
+        new RegExp(`<meta[^>]*property=["']og:${property}["'][^>]*content=["']([^"']*)["']`, 'i')
+      ) || html.match(
+        new RegExp(`<meta[^>]*content=["']([^"']*)["'][^>]*property=["']og:${property}["']`, 'i')
+      );
+      if (ogMatch) return ogMatch[1];
+
+      // Try twitter: tags
+      const twitterMatch = html.match(
+        new RegExp(`<meta[^>]*name=["']twitter:${property}["'][^>]*content=["']([^"']*)["']`, 'i')
+      ) || html.match(
+        new RegExp(`<meta[^>]*content=["']([^"']*)["'][^>]*name=["']twitter:${property}["']`, 'i')
+      );
+      if (twitterMatch) return twitterMatch[1];
+
+      // Fallback for description
+      if (property === 'description') {
+        const descMatch = html.match(
+          /<meta[^>]*name=["']description["'][^>]*content=["']([^"']*)["']/i
+        ) || html.match(
+          /<meta[^>]*content=["']([^"']*)["'][^>]*name=["']description["']/i
+        );
+        if (descMatch) return descMatch[1];
+      }
+
+      return undefined;
+    };
+
+    // Get title from og:title or <title> tag
+    let title = getMetaContent('title');
+    if (!title) {
+      const titleMatch = html.match(/<title[^>]*>([^<]*)<\/title>/i);
+      title = titleMatch ? titleMatch[1].trim() : url;
+    }
+
+    const description = getMetaContent('description') || '';
+    const image = getMetaContent('image');
+
+    return {
+      title: title.substring(0, 300), // Limit title length
+      description: description.substring(0, 1000), // Limit description length
+      image,
+    };
+  } catch (error) {
+    console.error('Error fetching Open Graph data:', error);
+    return null;
+  }
+}
+
+function extractFirstUrl(text: string): string | null {
+  const urlRegex = /https?:\/\/[^\s<>\[\]()]+/gi;
+  const match = text.match(urlRegex);
+  return match ? match[0] : null;
+}
+
+async function createExternalEmbed(
+  agent: BskyAgent,
+  url: string
+): Promise<AppBskyEmbedExternal.Main | null> {
+  const ogData = await fetchOpenGraphData(url);
+  if (!ogData) return null;
+
+  let thumbBlob: BlobRef | undefined;
+
+  // Try to upload the thumbnail image if available
+  if (ogData.image) {
+    try {
+      // Handle relative URLs
+      let imageUrl = ogData.image;
+      if (imageUrl.startsWith('//')) {
+        imageUrl = 'https:' + imageUrl;
+      } else if (imageUrl.startsWith('/')) {
+        const urlObj = new URL(url);
+        imageUrl = urlObj.origin + imageUrl;
+      }
+
+      const { buffer } = await reduceImageBySize(imageUrl);
+      const uploadResponse = await agent.uploadBlob(new Blob([buffer]));
+      thumbBlob = uploadResponse.data.blob;
+    } catch (error) {
+      console.error('Error uploading thumbnail for embed card:', error);
+      // Continue without thumbnail
+    }
+  }
+
+  return {
+    $type: 'app.bsky.embed.external',
+    external: {
+      uri: url,
+      title: ogData.title,
+      description: ogData.description,
+      ...(thumbBlob ? { thumb: thumbBlob } : {}),
+    },
+  } satisfies AppBskyEmbedExternal.Main;
+}
+
 async function uploadVideo(
   agent: AtpAgent,
   videoPath: string
@@ -315,6 +434,15 @@ export class BlueskyProvider extends SocialAbstract implements SocialProvider {
             },
           })),
         };
+      } else {
+        // No media - check for URLs to create an external embed card
+        const firstUrl = extractFirstUrl(post.message);
+        if (firstUrl) {
+          const externalEmbed = await createExternalEmbed(agent, firstUrl);
+          if (externalEmbed) {
+            embed = externalEmbed;
+          }
+        }
       }
 
       // @ts-ignore