guix: Add opam importer.

* guix/scripts/import.scm (importers): Add opam.
* guix/scripts/import/opam.scm: New file.
* guix/import/opam.scm: New file.
* tests/opam.scm: New file.
* Makefile.am: Add them.
* doc/guix.texi (Invoking guix import): Document it.

1 files changed, 193 insertions, 0 deletions

diff --git a/guix/import/opam.scm b/guix/import/opam.scm
new file mode 100644
index 0000000000..f252bdc31a
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+++ b/guix/import/opam.scm
@@ -0,0 +1,193 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Julien Lepiller <julien@lepiller.eu>
+;;;
+;;; 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 import opam)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 vlist)
+  #:use-module ((ice-9 rdelim) #:select (read-line))
+  #:use-module (srfi srfi-1)
+  #:use-module (web uri)
+  #:use-module (guix http-client)
+  #:use-module (guix utils)
+  #:use-module (guix import utils)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:export (opam->guix-package))
+
+(define (opam-urls)
+  "Fetch the urls.txt file from the opam repository and returns the list of
+URLs it contains."
+  (let ((port (http-fetch/cached (string->uri "https://opam.ocaml.org/urls.txt"))))
+    (let loop ((result '()))
+      (let ((line (read-line port)))
+        (if (eof-object? line)
+          (begin
+            (close port)
+            result)
+          (loop (cons line result)))))))
+
+(define (vhash-ref hashtable key default)
+  (match (vhash-assoc key hashtable)
+    (#f default)
+    ((_ . x) x)))
+
+(define (hashtable-update hashtable line)
+  "Parse @var{line} to get the name and version of the package and adds them
+to the hashtable."
+  (let* ((line (string-split line #\ )))
+    (match line
+      ((url foo ...)
+       (if (equal? url "repo")
+         hashtable
+         (match (string-split url #\/)
+           ((type name1 versionstr foo ...)
+            (if (equal? type "packages")
+              (match (string-split versionstr #\.)
+                ((name2 versions ...)
+                 (let ((version (string-join versions ".")))
+                   (if (equal? name1 name2)
+                     (let ((curr (vhash-ref hashtable name1 '())))
+                       (vhash-cons name1 (cons version curr) hashtable))
+                     hashtable)))
+                (_ hashtable))
+              hashtable))
+           (_ hashtable))))
+      (_ hashtable))))
+
+(define (urls->hashtable urls)
+  "Transform urls.txt in a hashtable whose keys are package names and values
+the list of available versions."
+  (let ((hashtable vlist-null))
+    (let loop ((urls urls) (hashtable hashtable))
+      (match urls
+        (() hashtable)
+        ((url rest ...) (loop rest (hashtable-update hashtable url)))))))
+
+(define (latest-version versions)
+  "Find the most recent version from a list of versions."
+  (match versions
+    ((first rest ...)
+     (let loop ((versions rest) (m first))
+       (match versions
+         (() m)
+         ((first rest ...)
+          (loop rest (if (version>? m first) m first))))))))
+
+(define (fetch-package-url uri)
+  "Fetch and parse the url file.  Return the URL the package can be downloaded
+from."
+  (let ((port (http-fetch uri)))
+    (let loop ((result #f))
+      (let ((line (read-line port)))
+        (if (eof-object? line)
+          (begin
+            (close port)
+            result)
+          (let* ((line (string-split line #\ )))
+            (match line
+              ((key value rest ...)
+               (if (member key '("archive:" "http:"))
+                 (loop (string-trim-both value #\"))
+                 (loop result))))))))))
+
+(define (fetch-package-metadata uri)
+  "Fetch and parse the opam file.  Return an association list containing the
+homepage, the license and the list of inputs."
+  (let ((port (http-fetch uri)))
+    (let loop ((result '()) (dependencies? #f))
+      (let ((line (read-line port)))
+        (if (eof-object? line)
+          (begin
+            (close port)
+            result)
+          (let* ((line (string-split line #\ )))
+            (match line
+               ((key value ...)
+                (let ((dependencies?
+                        (if dependencies?
+                          (not (equal? key "]"))
+                          (equal? key "depends:")))
+                      (val (string-trim-both (string-join value "") #\")))
+                  (cond
+                    ((equal? key "homepage:")
+                     (loop (cons `("homepage" . ,val) result) dependencies?))
+                    ((equal? key "license:")
+                     (loop (cons `("license" . ,val) result) dependencies?))
+                    ((and dependencies? (not (equal? val "[")))
+                     (match (string-split val #\{)
+                       ((val rest ...)
+                        (let ((curr (assoc-ref result "inputs"))
+                              (new (string-trim-both
+                                     val (list->char-set '(#\] #\[ #\")))))
+                          (loop (cons `("inputs" . ,(cons new (if curr curr '()))) result)
+                                (if (string-contains val "]") #f dependencies?))))))
+                    (else (loop result dependencies?))))))))))))
+
+(define (string->license str)
+  (cond
+    ((equal? str "MIT") '(license:expat))
+    ((equal? str "GPL2") '(license:gpl2))
+    ((equal? str "LGPLv2") '(license:lgpl2))
+    (else `())))
+
+(define (ocaml-name->guix-name name)
+  (cond
+    ((equal? name "ocamlfind") "ocaml-findlib")
+    ((string-prefix? "ocaml" name) name)
+    ((string-prefix? "conf-" name) (substring name 5))
+    (else (string-append "ocaml-" name))))
+
+(define (dependencies->inputs dependencies)
+  "Transform the list of dependencies in a list of inputs."
+  (if (not dependencies)
+    '()
+    (map (lambda (input)
+           (list input (list 'unquote (string->symbol input))))
+         (map ocaml-name->guix-name dependencies))))
+
+(define (opam->guix-package name)
+  (let* ((hashtable (urls->hashtable (opam-urls)))
+         (versions (vhash-ref hashtable name #f)))
+    (unless (eq? versions #f)
+      (let* ((version (latest-version versions))
+             (package-url (string-append "https://opam.ocaml.org/packages/" name
+                                         "/" name "." version "/"))
+             (url-url (string-append package-url "url"))
+             (opam-url (string-append package-url "opam"))
+             (source-url (fetch-package-url url-url))
+             (metadata (fetch-package-metadata opam-url))
+             (dependencies (assoc-ref metadata "inputs"))
+             (inputs (dependencies->inputs dependencies)))
+        (call-with-temporary-output-file
+          (lambda (temp port)
+            (and (url-fetch source-url temp)
+                 `(package
+                    (name ,(ocaml-name->guix-name name))
+                    (version ,version)
+                    (source
+                      (origin
+                        (method url-fetch)
+                        (uri ,source-url)
+                        (sha256 (base32 ,(guix-hash-url temp)))))
+                    (build-system ocaml-build-system)
+                    ,@(if (null? inputs)
+                        '()
+                        `((inputs ,(list 'quasiquote inputs))))
+                    (home-page ,(assoc-ref metadata "homepage"))
+                    (synopsis "")
+                    (description "")
+                    (license ,@(string->license (assoc-ref metadata "license")))))))))))