;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2016, 2017, 2018, 2019, 2020, 2021 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 (gnu)
  #:use-module (guix)
  #:use-module (guix ui)
  #:use-module (guix config)
  #:use-module (guix modules)
  #:use-module (guix build-system gnu)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (rnrs io ports)
  #:use-module (ice-9 match)
  #:use-module (ice-9 popen)
  #: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:


;;;
;;; Generating (guix config).
;;;
;;; This is copied from (guix self) because we cannot assume (guix self) is
;;; available at this point.
;;;

(define %persona-variables
  ;; (guix config) variables that define Guix's persona.
  '(%guix-package-name
    %guix-version
    %guix-bug-report-address
    %guix-home-page-url))

(define %config-variables
  ;; (guix config) variables corresponding to Guix configuration.
  (letrec-syntax ((variables (syntax-rules ()
                               ((_)
                                '())
                               ((_ variable rest ...)
                                (cons `(variable . ,variable)
                                      (variables rest ...))))))
    (variables %localstatedir %storedir %sysconfdir %system)))

(define* (make-config.scm #:key gzip xz bzip2
                          (package-name "GNU Guix")
                          (package-version "0")
                          (bug-report-address "bug-guix@gnu.org")
                          (home-page-url "https://guix.gnu.org"))

  ;; Hack so that Geiser is not confused.
  (define defmod 'define-module)

  (scheme-file "config.scm"
               #~(begin
                   (#$defmod (guix config)
                     #:export (%guix-package-name
                               %guix-version
                               %guix-bug-report-address
                               %guix-home-page-url
                               %store-directory
                               %state-directory
                               %store-database-directory
                               %config-directory
                               %libz
                               %gzip
                               %bzip2
                               %xz))

                   ;; XXX: Work around <http://bugs.gnu.org/15602>.
                   (eval-when (expand load eval)
                     #$@(map (match-lambda
                               ((name . value)
                                #~(define-public #$name #$value)))
                             %config-variables)

                     (define %store-directory
                       (or (and=> (getenv "NIX_STORE_DIR") canonicalize-path)
                           %storedir))

                     (define %state-directory
                       ;; This must match `NIX_STATE_DIR' as defined in
                       ;; `nix/local.mk'.
                       (or (getenv "GUIX_STATE_DIRECTORY")
                           (string-append %localstatedir "/guix")))

                     (define %store-database-directory
                       (or (getenv "GUIX_DATABASE_DIRECTORY")
                           (string-append %state-directory "/db")))

                     (define %config-directory
                       ;; This must match `GUIX_CONFIGURATION_DIRECTORY' as
                       ;; defined in `nix/local.mk'.
                       (or (getenv "GUIX_CONFIGURATION_DIRECTORY")
                           (string-append %sysconfdir "/guix")))

                     (define %guix-package-name #$package-name)
                     (define %guix-version #$package-version)
                     (define %guix-bug-report-address #$bug-report-address)
                     (define %guix-home-page-url #$home-page-url)

                     (define %gzip
                       #+(and gzip (file-append gzip "/bin/gzip")))
                     (define %bzip2
                       #+(and bzip2 (file-append bzip2 "/bin/bzip2")))
                     (define %xz
                       #+(and xz (file-append xz "/bin/xz")))))))


;;;
;;; 'gexp->script'.
;;;
;;; This is our own variant of 'gexp->script' with an extra #:module-path
;;; parameter, which was unavailable in (guix gexp) until commit
;;; 1ae16033f34cebe802023922436883867010850f (March 2018.)
;;;

(define (load-path-expression modules path)
  "Return as a monadic value a gexp that sets '%load-path' and
'%load-compiled-path' to point to MODULES, a list of module names.  MODULES
are searched for in PATH."
  (mlet %store-monad ((modules  (imported-modules modules
                                                  #:module-path path))