[bug#28251] [PATCH 3/3] import: Add JSON importer.

[Ricardo Wurmus <rekado@elephly.net>]

* guix/scripts/import/json.scm: New file.
* guix/scripts/import.scm (importers): Add json.
---
 guix/scripts/import.scm      |   2 +-
 guix/scripts/import/json.scm | 101 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 guix/scripts/import/json.scm

diff --git a/guix/scripts/import.scm b/guix/scripts/import.scm
index 9bba074e8..67bc7a755 100644
--- a/guix/scripts/import.scm
+++ b/guix/scripts/import.scm
@@ -74,7 +74,7 @@ rather than \\n."
 ;;;
 
 (define importers '("gnu" "nix" "pypi" "cpan" "hackage" "stackage" "elpa" "gem"
-                    "cran" "crate" "texlive"))
+                    "cran" "crate" "texlive" "json"))
 
 (define (resolve-importer name)
   (let ((module (resolve-interface
diff --git a/guix/scripts/import/json.scm b/guix/scripts/import/json.scm
new file mode 100644
index 000000000..b459ef819
--- /dev/null
+++ b/guix/scripts/import/json.scm
@@ -0,0 +1,101 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2014 Eric Bavier <bavier@member.fsf.org>
+;;; Copyright © 2015, 2017 Ricardo Wurmus <rekado@elephly.net>
+;;;
+;;; 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 scripts import json)
+  #:use-module (json)
+  #:use-module (guix ui)
+  #:use-module (guix utils)
+  #:use-module (guix scripts)
+  #:use-module (guix import utils)
+  #:use-module (guix scripts import)
+  #:use-module (guix packages)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-9 gnu)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-37)
+  #:use-module (srfi srfi-41)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 rdelim)
+  #:use-module (ice-9 format)
+  #:export (guix-import-json))
+
+\f
+;;;
+;;; Command-line options.
+;;;
+
+(define %default-options
+  '())
+
+(define (show-help)
+  (display (G_ "Usage: guix import json PACKAGE-FILE
+Import and convert the JSON package definition in PACKAGE-FILE.\n"))
+  (display (G_ "
+  -h, --help             display this help and exit"))
+  (display (G_ "
+  -V, --version          display version information and exit"))
+  (newline)
+  (show-bug-report-information))
+
+(define %options
+  ;; Specification of the command-line options.
+  (cons* (option '(#\h "help") #f #f
+                 (lambda args
+                   (show-help)
+                   (exit 0)))
+         (option '(#\V "version") #f #f
+                 (lambda args
+                   (show-version-and-exit "guix import json")))
+         %standard-import-options))
+
+\f
+;;;
+;;; Entry point.
+;;;
+
+(define (guix-import-json . args)
+  (define (parse-options)
+    ;; Return the alist of option values.
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (G_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
+
+  (let* ((opts (parse-options))
+         (args (filter-map (match-lambda
+                            (('argument . value)
+                             value)
+                            (_ #f))
+                           (reverse opts))))
+    (match args
+      ((file-name)
+       (catch 'json-invalid
+         (lambda ()
+           (let ((json (json-string->scm
+                        (with-input-from-file file-name read-string))))
+             ;; TODO: also print define-module boilerplate
+             (package->code (data->guix-package (hash-table->alist json)))))
+         (lambda ()
+           (leave (G_ "invalid JSON in file '~a'~%") file-name))))
+      (()
+       (leave (G_ "too few arguments~%")))
+      ((many ...)
+       (leave (G_ "too many arguments~%"))))))
-- 
2.14.1