Resolve external embed previews and keep their real MIME types

media-scrape/test/run.ts

@@ -10,6 +10,7 @@ import { existsSync, mkdirSync, mkdtempSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { downloadOne, downloadPreview, previewUrlFor, videoPoster } from "../src/download.js";
+import { ogImageFromHtml, resolveEmbedPreview } from "../src/embed-preview.js";
 import { ScrapeEngine, type FetchPage, type ScrapeBackend } from "../src/engine.js";
 import { extractMedia } from "../src/extract.js";
 import { PuppetBackend } from "../src/puppet-backend.js";
@@ -549,6 +550,17 @@ void (async () => {
         assert.equal(outcome.state, "downloaded");
         assert.equal(outcome.path, `${outcome.hash}.webp`);
         assert.equal(existsSync(join(dir, `${outcome.hash}.webp`)), true);
+
+        const jpeg = await downloadPreview(
+            { id: 10, url: "https://cdn.discordapp.com/attachments/1/2/pic.png", kind: "image", source: "attachment", preview_url: null },
+            dir,
+            {
+                fetchImpl: async () =>
+                    new Response("jpeg-bytes", { status: 200, headers: { "content-type": "image/jpeg" } })
+            }
+        );
+        assert.equal(jpeg.path, `${jpeg.hash}.jpg`);
+        assert.equal(existsSync(join(dir, `${jpeg.hash}.jpg`)), true);
     });
 
     await test("embed thumbnails download only when enabled", async () => {
@@ -635,6 +647,7 @@ void (async () => {
         const row = store.queryMedia({ kind: "image" })[0];
         assert.ok(row.preview_hash);
         assert.ok((row.preview_bytes ?? 0) > 0);
+        assert.equal(row.preview_ext, "webp");
         store.close();
         assert.equal(existsSync(join(root, started.id, "thumbs", `${row.preview_hash}.webp`)), true);
     });
@@ -704,14 +717,82 @@ void (async () => {
 
         const embed = store.queryMedia({ kind: "video" })[0];
         assert.ok(embed.preview_hash);
-        assert.equal(
-            existsSync(join(dest, started.id, "thumbnails", `${embed.preview_hash}.webp`)),
-            true
-        );
-        assert.equal(existsSync(join(root, started.id, "thumbs", `${embed.preview_hash}.webp`)), true);
+        const previewFile = `${embed.preview_hash}.${embed.preview_ext ?? "webp"}`;
+        assert.equal(existsSync(join(dest, started.id, "thumbnails", previewFile)), true);
+        assert.equal(existsSync(join(root, started.id, "thumbs", previewFile)), true);
         store.close();
     });
 
+    await test("embed previews resolve from providers and og:image", async () => {
+        const fetchImpl = async (input: any) => {
+            const url = String(input);
+            if (url.includes("youtube.com/oembed")) {
+                return new Response(JSON.stringify({ thumbnail_url: "https://i.ytimg.com/ok.jpg" }), {
+                    status: 200
+                });
+            }
+            if (url.includes("api.fxtwitter.com")) {
+                return new Response(
+                    JSON.stringify({ tweet: { media: { videos: [{ thumbnail_url: "https://pbs.twimg.com/ok.jpg" }] } } }),
+                    { status: 200 }
+                );
+            }
+            if (url.includes("vxreddit.com")) {
+                return new Response(
+                    '<html><head><meta property="og:image" content="https://i.redd.it/ok.jpg"></head></html>',
+                    { status: 200 }
+                );
+            }
+            return new Response("no", { status: 404 });
+        };
+
+        assert.equal(
+            await resolveEmbedPreview(
+                { url: "https://youtu.be/abc", source: "embed", preview_url: null },
+                { fetchImpl }
+            ),
+            "https://i.ytimg.com/ok.jpg"
+        );
+        assert.equal(
+            await resolveEmbedPreview(
+                { url: "https://fxtwitter.com/u/status/12345", source: "embed", preview_url: null },
+                { fetchImpl }
+            ),
+            "https://pbs.twimg.com/ok.jpg"
+        );
+        assert.equal(
+            await resolveEmbedPreview(
+                { url: "https://vxreddit.com/r/x/comments/1", source: "embed", preview_url: null },
+                { fetchImpl }
+            ),
+            "https://i.redd.it/ok.jpg"
+        );
+        assert.equal(
+            await resolveEmbedPreview(
+                { url: "https://x.com/u/status/1", source: "embed", preview_url: "https://stored/ok.jpg" },
+                { fetchImpl }
+            ),
+            "https://stored/ok.jpg"
+        );
+        assert.equal(
+            await resolveEmbedPreview(
+                { url: "https://cdn.discordapp.com/x.png", source: "attachment", preview_url: null },
+                { fetchImpl }
+            ),
+            null
+        );
+
+        assert.equal(
+            ogImageFromHtml('<meta content="https://a/1.jpg" property="og:image">'),
+            "https://a/1.jpg"
+        );
+        assert.equal(
+            ogImageFromHtml('<meta name="twitter:image" content="https://a/2.jpg">'),
+            "https://a/2.jpg"
+        );
+        assert.equal(ogImageFromHtml("<html></html>"), null);
+    });
+
     await test("videoPoster extracts a cached frame", async () => {
         const dir = join(root, "poster-test");
         mkdirSync(dir, { recursive: true });