feat(users): gestione utenti /admin/users con guardie self/ultimo-admin

src/lib/auth.ts

@@ -78,6 +78,36 @@ export function listUsers(db: Database.Database): { id: number; username: string
     { id: number; username: string; role: string }[];
 }
 
+export function countAdmins(db: Database.Database): number {
+  return (db.prepare("SELECT COUNT(*) AS n FROM users WHERE role = 'admin'").get() as { n: number }).n;
+}
+
+export function getUserById(db: Database.Database, id: number): { id: number; username: string; role: string } | null {
+  const row = db.prepare('SELECT id, username, role FROM users WHERE id = ?').get(id) as
+    { id: number; username: string; role: string } | undefined;
+  return row ?? null;
+}
+
+export function updateUserRole(db: Database.Database, id: number, role: Role): void {
+  db.prepare('UPDATE users SET role = ? WHERE id = ?').run(role, id);
+}
+
+export function updateUserPassword(db: Database.Database, id: number, hash: string): void {
+  db.prepare('UPDATE users SET password_hash = ? WHERE id = ?').run(hash, id);
+}
+
+export function deleteUser(db: Database.Database, id: number): void {
+  db.prepare('DELETE FROM users WHERE id = ?').run(id);
+}
+
+export function randomPassword(): string {
+  return randomBytes(9).toString('base64url'); // ~12 caratteri
+}
+
+export function isRole(v: unknown): v is Role {
+  return v === 'admin' || v === 'superuser' || v === 'user';
+}
+
 export function landingFor(role: string): string {
   if (role === 'superuser') return '/admin/content';
   return '/admin';