feat: add bulk YouTube thumbnail download endpoint

POST /api/youtube/thumbnails/bulk (Super-Admin only)
Supports ?dryRun=true for preview. Downloads sequentially with 500ms delay.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/(payload)/api/youtube/thumbnails/bulk/route.ts

@@ -0,0 +1,94 @@
+import { NextResponse, type NextRequest } from 'next/server'
+import { getPayload } from 'payload'
+import config from '@payload-config'
+import { downloadAndUploadImage } from '@/lib/utils/media-download'
+import { getYouTubeThumbnail } from '@/lib/utils/youtube'
+
+/**
+ * POST /api/youtube/thumbnails/bulk
+ *
+ * Bulk-Download von YouTube-Thumbnails für alle YouTubeContent-Einträge
+ * die noch kein Thumbnail haben. Erfordert Super-Admin-Rechte.
+ *
+ * Query-Parameter:
+ * - dryRun=true: Zeigt nur was passieren würde, ohne tatsächlich herunterzuladen
+ */
+export async function POST(req: NextRequest) {
+  try {
+    const payload = await getPayload({ config })
+
+    const { user } = await payload.auth({ headers: req.headers })
+    if (!user) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+    }
+
+    const typedUser = user as { isSuperAdmin?: boolean }
+    if (!typedUser.isSuperAdmin) {
+      return NextResponse.json({ error: 'Super-Admin erforderlich' }, { status: 403 })
+    }
+
+    const dryRun = req.nextUrl.searchParams.get('dryRun') === 'true'
+
+    // Find all YouTubeContent without thumbnail that have a videoId
+    const contentWithoutThumbnail = await payload.find({
+      collection: 'youtube-content',
+      where: {
+        thumbnail: { exists: false },
+        'youtube.videoId': { exists: true },
+      },
+      limit: 500,
+      depth: 0,
+    })
+
+    const results = { processed: 0, downloaded: 0, skipped: 0, errors: 0, dryRun }
+
+    for (const doc of contentWithoutThumbnail.docs) {
+      results.processed++
+      const videoId = doc.youtube?.videoId
+      if (!videoId) {
+        results.skipped++
+        continue
+      }
+
+      if (dryRun) {
+        results.downloaded++
+        continue
+      }
+
+      try {
+        const thumbnailUrl = getYouTubeThumbnail(videoId, 'hq')
+        const filename = `yt-thumb-${videoId}.jpg`
+        const tenantId = typeof doc.tenant === 'object' ? doc.tenant?.id : doc.tenant
+
+        const mediaId = await downloadAndUploadImage(payload, {
+          url: thumbnailUrl,
+          filename,
+          alt: `Thumbnail: ${typeof doc.title === 'string' ? doc.title : doc.title?.de || videoId}`,
+          tenantId: tenantId || undefined,
+        })
+
+        if (mediaId) {
+          await payload.update({
+            collection: 'youtube-content',
+            id: doc.id,
+            data: { thumbnail: mediaId },
+            depth: 0,
+          })
+          results.downloaded++
+        } else {
+          results.errors++
+        }
+      } catch {
+        results.errors++
+      }
+
+      // Rate-limit delay (500ms between downloads)
+      await new Promise((resolve) => setTimeout(resolve, 500))
+    }
+
+    return NextResponse.json(results)
+  } catch (error) {
+    console.error('[yt-thumbnail-bulk] Error:', error)
+    return NextResponse.json({ error: 'Internal Server Error' }, { status: 500 })
+  }
+}