feat: add token create/validate utilities

src/lib/token.ts

@@ -0,0 +1,25 @@
+import { prisma } from './prisma'
+import { config } from '../../config/app.config'
+
+export async function createToken(downloadId: string): Promise<string> {
+  const expiresAt = new Date(
+    Date.now() + config.DOWNLOAD_LINK_TTL_HOURS * 60 * 60 * 1000
+  )
+  const record = await prisma.downloadToken.create({
+    data: { downloadId, expiresAt },
+  })
+  return record.token
+}
+
+export async function validateToken(
+  token: string
+): Promise<{ downloadId: string; filePath: string } | null> {
+  const record = await prisma.downloadToken.findUnique({
+    where: { token },
+    include: { download: { select: { id: true, filePath: true } } },
+  })
+  if (!record) return null
+  if (record.expiresAt < new Date()) return null
+  if (!record.download.filePath) return null
+  return { downloadId: record.download.id, filePath: record.download.filePath }
+}