notFeat: Don't expect much from this added route, I won't add more than essential.

src/pages/api/oembed/[id].tsx

@@ -0,0 +1,75 @@
+import { NextApiReq, NextApiRes, withZipline } from 'middleware/withZipline';
+import 'lib/prisma';
+import 'lib/config';
+
+async function handler(req: NextApiReq, res: NextApiRes) {
+  const { id } = req.query as { id: string };
+  if (req.method === 'GET') {
+    if (!id || isNaN(parseInt(id))) return res.badRequest('no id');
+
+    const file = await prisma.file.findUnique({
+      where: {
+        id: parseInt(id),
+      },
+      include: {
+        thumbnail: {
+          select: {
+            name: true,
+          },
+        },
+        user: {
+          select: {
+            username: true,
+          },
+        },
+      },
+    });
+    if (!file || !!file.password) return res.notFound('no such file exists');
+
+    const mediaType: 'image' | 'video' | 'audio' | 'other' =
+      (new RegExp(/^(?<type>image|video|audio)/).exec(file.mimetype)?.groups?.type as
+        | 'image'
+        | 'video'
+        | 'audio') || 'other';
+
+    let host = req.headers.host;
+    const proto = req.headers['x-forwarded-proto'];
+    try {
+      if (
+        JSON.parse(req.headers['cf-visitor'] as string).scheme === 'https' ||
+        proto === 'https' ||
+        config.core.return_https
+      )
+        host = `https://${host}`;
+      else host = `http://${host}`;
+    } catch (e) {
+      if (proto === 'https' || config.core.return_https) host = `https://${host}`;
+      else host = `http://${host}`;
+    }
+
+    if (mediaType === 'image')
+      return res.json({
+        type: 'photo',
+        version: '1.0',
+        url: `${host}/r/${file.name}`,
+      });
+    if (mediaType === 'video')
+      return res.json({
+        type: 'video',
+        version: '1.0',
+        url: `${host}/r/${file.name}`,
+        thumbnail_url: file.thumbnail ? `${host}/r/${file.thumbnail.name}` : undefined,
+        html: `<video src="${host}/r/${file.name}"/>`,
+      });
+    return res.json({
+      type: 'link',
+      version: '1.0',
+      url: `${host}${config.uploader.route}/${file.name}`,
+    });
+  }
+}
+
+export default withZipline(handler, {
+  methods: ['GET'],
+  user: false,
+});