feat(admin): consentement aux annonces et désabonnement sans connexion

Les comptes déjà créés ne sont pas inscrits. Le choix est facultatif à l’inscription et dans les paramètres. Un lien public demande confirmation avant d’arrêter les actualités, sans toucher aux messages de compte.

memento-note/lib/marketing/unsubscribe-token.ts

@@ -0,0 +1,71 @@
+import { createHmac, timingSafeEqual } from 'crypto'
+
+const TOKEN_TTL_MS = 10 * 365 * 24 * 60 * 60 * 1000
+
+function getSecret(): string {
+  const secret = process.env.NEXTAUTH_SECRET
+  if (!secret) {
+    throw new Error('NEXTAUTH_SECRET is required for unsubscribe tokens')
+  }
+  return secret
+}
+
+export type UnsubscribeTokenPayload = {
+  userId: string
+  issuedAt: number
+}
+
+export function createUnsubscribeToken(userId: string): string {
+  const issuedAt = Date.now()
+  const inner = Buffer.from(`${userId}.${issuedAt}`, 'utf8').toString('base64url')
+  const sig = createHmac('sha256', getSecret()).update(inner).digest('base64url')
+  return `${inner}.${sig}`
+}
+
+export function verifyUnsubscribeToken(token: string): UnsubscribeTokenPayload | null {
+  try {
+    const trimmed = token.trim()
+    const lastDot = trimmed.lastIndexOf('.')
+    if (lastDot <= 0) return null
+    const sig = trimmed.slice(lastDot + 1)
+    const inner = trimmed.slice(0, lastDot)
+    const expected = createHmac('sha256', getSecret()).update(inner).digest('base64url')
+    const sigBuf = Buffer.from(sig)
+    const expectedBuf = Buffer.from(expected)
+    if (sigBuf.length !== expectedBuf.length || !timingSafeEqual(sigBuf, expectedBuf)) {
+      return null
+    }
+    const decoded = Buffer.from(inner, 'base64url').toString('utf8')
+    const firstDot = decoded.indexOf('.')
+    if (firstDot <= 0) return null
+    const userId = decoded.slice(0, firstDot)
+    const issuedAt = Number(decoded.slice(firstDot + 1))
+    if (!userId || !Number.isFinite(issuedAt)) return null
+    if (Date.now() - issuedAt > TOKEN_TTL_MS) return null
+    return { userId, issuedAt }
+  } catch {
+    return null
+  }
+}
+
+export function publicAppOrigin(): string {
+  return (process.env.NEXTAUTH_URL || '').replace(/\/$/, '')
+}
+
+export function unsubscribePageUrl(token: string): string {
+  return `${publicAppOrigin()}/unsubscribe?token=${encodeURIComponent(token)}`
+}
+
+export function unsubscribeOneClickUrl(token: string): string {
+  return `${publicAppOrigin()}/api/marketing/unsubscribe?token=${encodeURIComponent(token)}`
+}
+
+/** Headers for future campaign messages (RFC 8058). */
+export function listUnsubscribeHeaders(token: string): Record<string, string> {
+  const page = unsubscribePageUrl(token)
+  const oneClick = unsubscribeOneClickUrl(token)
+  return {
+    'List-Unsubscribe': `<${oneClick}>, <${page}>`,
+    'List-Unsubscribe-Post': 'List-Unsubscribe=One-Click',
+  }
+}