;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix 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 General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu services dmd)
  #:use-module (guix monads)
  #:use-module (gnu services)
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:export (dmd-configuration-file))

;;; Commentary:
;;;
;;; Instantiating system services as a dmd configuration file.
;;;
;;; Code:

(define (dmd-configuration-file services etc)
  "Return the dmd configuration file for SERVICES, that initializes /etc from
ETC (the name of a directory in the store) on startup."
  (define config
    `(begin
       (use-modules (ice-9 ftw))

       (register-services
        ,@(map (lambda (service)
                `(make <service>
                   #:docstring ',(service-documentation service)
                   #:provides ',(service-provision service)
                   #:requires ',(service-requirement service)
                   #:respawn? ',(service-respawn? service)
                   #:start ,(service-start service)
                   #:stop ,(service-stop service)))
               services))

       ;; /etc is a mixture of static and dynamic settings.  Here is where we
       ;; initialize it from the static part.
       (format #t "populating /etc from ~a...~%" ,etc)
       (let ((rm-f (lambda (f)
                     (false-if-exception (delete-file f)))))
         (rm-f "/etc/static")
         (symlink ,etc "/etc/static")
         (for-each (lambda (file)
                     ;; TODO: Handle 'shadow' specially so that changed
                     ;; password aren't lost.
                     (let ((target (string-append "/etc/" file))
                           (source (string-append "/etc/static/" file)))
                       (rm-f target)
                       (symlink source target)))
                   (scandir ,etc
                            (lambda (file)
                              (not (member file '("." ".."))))))

         ;; Prevent ETC from being GC'd.
         (rm-f "/var/nix/gcroots/etc-directory")
         (symlink ,etc "/var/nix/gcroots/etc-directory"))

       (format #t "starting services...~%")
       (for-each start ',(append-map service-provision services))))

  (text-file "dmd.conf" (object->string config)))

;;; dmd.scm ends here