;;; Nar Herder
;;;
;;; Copyright © 2021 Christopher Baines <mail@cbaines.net>
;;;
;;; 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
;;; <http://www.gnu.org/licenses/>.

(define-module (nar-herder recent-changes)
  #:use-module (srfi srfi-1)
  #:use-module (ice-9 threads)
  #:use-module (nar-herder database)
  #:export (start-recent-change-removal-and-database-dump-thread))

(define (start-recent-change-removal-and-database-dump-thread database
                                                              database-dump-filename
                                                              check-interval
                                                              recent-changes-limit)
  (define (update-database-dump)
    (let ((temp-database-dump-filename
           (string-append database-dump-filename ".tmp")))

      (when (file-exists? temp-database-dump-filename)
        (delete-file temp-database-dump-filename))

      (dump-database database temp-database-dump-filename)

      (rename-file temp-database-dump-filename
                   database-dump-filename)

      (simple-format (current-error-port)
                     "updated database dump\n")))

  (call-with-new-thread
   (lambda ()
     (while #t
       (let ((recent-changes-id-for-deletion
              (database-get-recent-changes-id-for-deletion database
                                                           recent-changes-limit)))
         (when recent-changes-id-for-deletion
           (update-database-dump)

           (let ((deleted-recent-changes
                  (database-delete-recent-changes-with-id-below
                   database
                   recent-changes-id-for-deletion)))
             (simple-format (current-error-port)
                            "deleted ~A recent changes\n"
                            deleted-recent-changes)))

         (sleep check-interval))))))