;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2015 Pjotr Prins <pjotr.public01@thebird.nl>
;;;
;;; 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 (guix build ruby-build-system)
  #:use-module ((guix build gnu-build-system) #:prefix gnu:)
  #:use-module (guix build utils)
  #:use-module (ice-9 match)
  #:use-module (ice-9 popen)
  #:use-module (ice-9 regex)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:export (%standard-phases
            ruby-build))

;; Commentary:
;;
;; Builder-side code of the standard Ruby package build procedure.
;;
;; Code:

(define (first-matching-file pattern)
  "Return the first file name that matches PATTERN in the current working
directory."
  (match (find-files "." pattern)
    ((file-name . _) file-name)
    (() (error "No files matching pattern: " pattern))))

(define* (unpack #:key source #:allow-other-keys)
  "Unpack the gem SOURCE and enter the resulting directory."
  (and (zero? (system* "gem" "unpack" source))
       (begin
         ;; The unpacked gem directory is named the same as the archive, sans
         ;; the ".gem" extension.
         (chdir (match:substring (string-match "^(.*)\\.gem$"
                                               (basename source))
                                 1))
         #t)))

(define* (build #:key source #:allow-other-keys)
  "Build a new gem using the gemspec from the SOURCE gem."

  ;; Remove the original gemspec, if present, and replace it with a new one.
  ;; This avoids issues with upstream gemspecs requiring tools such as git to
  ;; generate the files list.
  (let ((gemspec (or (false-if-exception
                      (first-matching-file "\\.gemspec$"))
                     ;; Make new gemspec if one wasn't shipped.
                     ".gemspec")))

    (when (file-exists? gemspec) (delete-file gemspec))

    ;; Extract gemspec from source gem.
    (let ((pipe (open-pipe* OPEN_READ "gem" "spec" "--ruby" source)))
      (dynamic-wind
        (const #t)
        (lambda ()
          (call-with-output-file gemspec
            (lambda (out)
              ;; 'gem spec' writes to stdout, but 'gem build' only reads
              ;; gemspecs from a file, so we redirect the output to a file.
              (while (not (eof-object? (peek-char pipe)))
                (write-char (read-char pipe) out))))
          #t)
        (lambda ()
          (close-pipe pipe))))

    ;; Build a new gem from the current working directory.  This also allows any
    ;; dynamic patching done in previous phases to be present in the installed
    ;; gem.
    (zero? (system* "gem" "build" gemspec))))

(define* (check #:key tests? test-target #:allow-other-keys)
  "Run the gem's test suite rake task TEST-TARGET.  Skip the tests if TESTS?
is #f."
  (if tests?
      (zero? (system* "rake" test-target))
      #t))

(define* (install #:key inputs outputs (gem-flags '())
                  #:allow-other-keys)
  "Install the gem archive SOURCE to the output store item.  Additional
GEM-FLAGS are passed to the 'gem' invokation, if present."
  (let* ((ruby-version
          (match:substring (string-match "ruby-(.*)\\.[0-9]$"
                                         (assoc-ref inputs "ruby"))
                           1))
         (out (assoc-ref outputs "out"))
         (gem-home (string-append out "/lib/ruby/gems/" ruby-version ".0")))

    (setenv "GEM_HOME" gem-home)
    (mkdir-p gem-home)
    (zero? (apply system* "gem" "install" (first-matching-file "\\.gem$")
                  "--local" "--ignore-dependencies"
                  ;; Executables should go into /bin, not /lib/ruby/gems.
                  "--bindir" (string-append out "/bin")
                  gem-flags))))

(define %standard-phases
  (modify-phases gnu:%standard-phases
    (delete 'configure)
    (replace 'build build)
    (replace 'unpack unpack)
    (replace 'install install)
    (replace 'check check)))

(define* (ruby-build #:key inputs (phases %standard-phases)
                     #:allow-other-keys #:rest args)
  (apply gnu:gnu-build #:inputs inputs #:phases phases args))
