;; webid-oidc, implementation of the Solid specification
;; Copyright (C) 2020, 2021  Vivien Kraus

;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU Affero General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU Affero General Public License for more details.

;; You should have received a copy of the GNU Affero General Public License
;; along with this program.  If not, see <https://www.gnu.org/licenses/>.

(define-module (webid-oidc jti)
  #:use-module ((webid-oidc parameters) #:prefix p:)
  #:use-module (ice-9 atomic)
  #:use-module (ice-9 threads)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-19)
  #:export (jti-check))

(define jti-list
  (make-atomic-box '()))

(define-record-type <jti-item>
  (make-jti-item exp jti)
  jti-item?
  (exp jti-item-exp)
  (jti jti-item-jti))

(define lookup
  (match-lambda*
    ((() item) #f)
    (((($ <jti-item> exp jti) other ...) item)
     (or (string=? jti item)
         (lookup other item)))))

(define (jti-check jti valid-time)
  (let* ((current-time
          (time-second (date->time-utc ((p:current-date)))))
         (old (atomic-box-ref jti-list))
         (new-entry (make-jti-item (+ current-time valid-time) jti))
         (new (filter
               (match-lambda
                 (($ <jti-item> exp other-jti)
                  (>= exp current-time)))
               (cons new-entry old))))
    (and (not (lookup old jti))
         (let ((discarded (atomic-box-compare-and-swap! jti-list old new)))
           (if (eq? discarded old)
               #t
               (jti-check jti valid-time))))))