(= sessions* "sessions/")

(def rand-id ()
  (rand-string 10))

(def ok-id (x)
  (and (is (len x) 10) (all alphadig x)))

(def check-id (x)
  (check x ok-id))

(def session-id ()
  (only.check-id (alref req!cooks "session")))

(def read-session (id)
  (errsafe (readfile1 (string sessions* id))))

(dynvar session)

(def save-session ()
  (ensure-dir sessions*)
  (writefile session (string sessions* session!id)))

(def gen-session ()
  (let session-id (session-id)
    (if session-id
         (list (or (read-session session-id) (obj id session-id) nil))
         (let id (rand-id)
           (list (obj id id) `("session" ,id))))))

(def establish-session ()
  (let (session cook) (gen-session)
    (push cook req!cookies-to-set)
    session))

(mac with-session body
  `(dlet session (establish-session)
     (after (do ,@body)
            (save-session))))