;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2016, 2017 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 (build-self)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-19)
  #:use-module (ice-9 match)
  #:export (build))

;;; Commentary:
;;;
;;; When loaded, this module returns a monadic procedure of at least one
;;; argument: the source tree to build.  It returns a derivation that
;;; builds it.
;;;
;;; This file uses modules provided by the already-installed Guix.  Those
;;; modules may be arbitrarily old compared to the version we want to
;;; build.  Because of that, it must rely on the smallest set of features
;;; that are likely to be provided by the (guix) and (gnu) modules, and by
;;; Guile itself, forever and ever.
;;;
;;; Code:

;; Use our very own Guix modules.
(eval-when (compile load eval)

  ;; Ignore any available .go, and force recompilation.  This is because our
  ;; checkout in the store has mtime set to the epoch, and thus .go files look
  ;; newer, even though they may not correspond.
  (set! %fresh-auto-compile #t)

  (and=> (assoc-ref (current-source-location) 'filename)
         (lambda (file)
           (let ((dir (string-append (dirname file) "/../..")))
             (set! %load-path (cons dir %load-path))))))

(define (date-version-string)
  "Return the current date and hour in UTC timezone, for use as a poor
person's version identifier."
  ;; XXX: Last resort when the Git commit id is missing.
  (date->string (current-date 0) "~Y~m~d.~H"))

;; The procedure below is our return value.
(define* (build source
                #:key verbose? (version (date-version-string))
                #:allow-other-keys
                #:rest rest)
  "Return a derivation that unpacks SOURCE into STORE and compiles Scheme
files."
  ;; FIXME: Closures in (guix scripts pull) have already cached old values of
  ;; (guix …), so they keep referring to the "old" world, with different
  ;; record types than the one we get after reloading (because record types
  ;; are "generative".)
  ;; (let ((reload-guix (module-ref (resolve-interface '(guix self))
  ;;                                'reload-guix)))
  ;;   (reload-guix))                                ;cross fingers!

  (let ((guix-derivation (module-ref (resolve-interface '(guix self))
                                     'guix-derivation)))
    (guix-derivation source version)))

;; This file is loaded by 'guix pull'; return it the build procedure.
build

;;; build-self.scm ends here