session livekit token

server/utils/livekit.ts

@@ -0,0 +1,78 @@
+import type { Session, User } from 'lucia'
+import { Buffer } from 'node:buffer'
+import { AccessToken } from 'livekit-server-sdk'
+import { SESSION_EXPIRES_IN } from '../auth/lucia.ts'
+import prisma from '../prisma/client.ts'
+
+/**
+ * Re-issue the token slightly before it actually expires, so a client that
+ * caches the /me response for a while still gets a usable token.
+ */
+const REFRESH_BEFORE_EXPIRY_SECONDS = 60 * 60
+
+export async function createLivekitToken(user: User, ttlSeconds: number) {
+  const apiKey = process.env.LIVEKIT_API_KEY
+  const apiSecret = process.env.LIVEKIT_API_SECRET
+
+  if (!apiKey || !apiSecret)
+    throw new Error('LIVEKIT_API_KEY and LIVEKIT_API_SECRET must be set')
+
+  const token = new AccessToken(apiKey, apiSecret, {
+    identity: user.id,
+    name: user.displayName,
+    ttl: ttlSeconds,
+  })
+
+  token.addGrant({
+    room: process.env.LIVEKIT_ROOM || 'chad',
+    roomJoin: true,
+    canPublish: true,
+    canSubscribe: true,
+    canPublishData: true,
+    canUpdateOwnMetadata: true,
+  })
+
+  return token.toJwt()
+}
+
+/** Mints the token that gets stored on a session at the moment it is created. */
+export function createSessionLivekitToken(user: User) {
+  return createLivekitToken(user, SESSION_EXPIRES_IN.seconds())
+}
+
+/**
+ * Returns the token stored alongside the session, re-issuing and persisting it
+ * when it is missing (session predates the column) or about to expire (Lucia
+ * extends `expiresAt` on active sessions, outliving the original token).
+ */
+export async function getSessionLivekitToken(user: User, session: Session) {
+  if (session.livekitToken && !isExpiringSoon(session.livekitToken))
+    return session.livekitToken
+
+  const ttlSeconds = Math.max(
+    Math.ceil((session.expiresAt.getTime() - Date.now()) / 1000),
+    REFRESH_BEFORE_EXPIRY_SECONDS,
+  )
+  const livekitToken = await createLivekitToken(user, ttlSeconds)
+
+  await prisma.session.update({
+    where: { id: session.id },
+    data: { livekitToken },
+  })
+
+  session.livekitToken = livekitToken
+
+  return livekitToken
+}
+
+function isExpiringSoon(token: string) {
+  try {
+    const [, payload] = token.split('.')
+    const { exp } = JSON.parse(Buffer.from(payload, 'base64url').toString())
+
+    return typeof exp !== 'number' || exp - REFRESH_BEFORE_EXPIRY_SECONDS <= Date.now() / 1000
+  }
+  catch {
+    return true
+  }
+}