;; dislfuid, implementation of the Solid specification
;; Copyright (C) 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 offloading)
  #:use-module (ice-9 threads)
  #:declarative? #t
  #:export (with-threads in-another-thread))

(define tag (make-prompt-tag))

(define (let-threads-escape thunk)
  (call-with-prompt tag
    (lambda ()
      (thunk))
    (lambda (k handle-continuation)
      (handle-continuation k))))

(define (continue-in-another-thread thunk)
  (abort-to-prompt
   tag
   (lambda (continuation)
     (call-with-new-thread
      (lambda ()
        (let-threads-escape
         (lambda ()
           (call-with-values
               thunk
             continuation))))))))

(define-syntax-rule (with-threads body ...)
  (let-threads-escape
   (lambda () body ...)))

(define-syntax-rule (in-another-thread body ...)
  (continue-in-another-thread
   (lambda () body ...)))