import: Add 'generic-git' updater.

* guix/git.scm (ls-remote-refs): New procedure.
* tests/git.scm ("remote-refs" "remote-refs: only tags"): New tests.
* guix/import/git.scm: New file.
* doc/guix.texi (Invoking guix refresh): Document it.
* tests/import-git.scm: New test file.
* Makefile.am (MODULES, SCM_TESTS): Register the new files.

Co-authored-by: Sarah Morgensen <iskarian@mgsn.dev>
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 225 insertions, 0 deletions

diff --git a/guix/import/git.scm b/guix/import/git.scm
new file mode 100644
index 0000000000..1eb219f3fe
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+++ b/guix/import/git.scm
@@ -0,0 +1,225 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
+;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
+;;;
+;;; 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 git)
+  #:use-module (guix build utils)
+  #:use-module (guix diagnostics)
+  #:use-module (guix git)
+  #:use-module (guix git-download)
+  #:use-module (guix i18n)
+  #:use-module (guix packages)
+  #:use-module (guix upstream)
+  #:use-module (guix utils)
+  #:use-module (ice-9 format)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 rdelim)
+  #:use-module (ice-9 regex)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-34)
+  #:use-module (srfi srfi-35)
+  #:export (%generic-git-updater
+
+            ;; For tests.
+            latest-git-tag-version))
+
+;;; Commentary:
+;;;
+;;; This module provides a generic package updater for packages hosted on Git
+;;; repositories.
+;;;
+;;; It tries to be smart about tag names, but if it is not automatically able
+;;; to parse the tag names correctly, users can set the `release-tag-prefix',
+;;; `release-tag-suffix' and `release-tag-version-delimiter' properties of the
+;;; package to make the updater parse the Git tag name correctly.
+;;;
+;;; Possible improvements:
+;;;
+;;; * More robust method for trying to guess the delimiter.  Maybe look at the
+;;;   previous version/tag combo to determine the delimiter.
+;;;
+;;; * Differentiate between "normal" versions, e.g., 1.2.3, and dates, e.g.,
+;;;   2021.12.31.  Honor a `release-tag-date-scheme?' property?
+;;;
+;;; Code:
+
+;;; Errors & warnings
+
+(define-condition-type &git-no-valid-tags-error &error
+  git-no-valid-tags-error?)
+
+(define (git-no-valid-tags-error)
+  (raise (condition (&message (message "no valid tags found"))
+                    (&git-no-valid-tags-error))))
+
+(define-condition-type &git-no-tags-error &error
+  git-no-tags-error?)
+
+(define (git-no-tags-error)
+  (raise (condition (&message (message "no tags were found"))
+                    (&git-no-tags-error))))
+
+
+;;; Updater
+
+(define %pre-release-words
+  '("alpha" "beta" "rc" "dev" "test" "pre"))
+
+(define %pre-release-rx
+  (map (lambda (word)
+         (make-regexp (string-append ".+" word) regexp/icase))
+       %pre-release-words))
+
+(define* (version-mapping tags #:key prefix suffix delim pre-releases?)
+  "Given a list of Git TAGS, return an association list where the car is the
+version corresponding to the tag, and the cdr is the name of the tag."
+  (define (guess-delimiter)
+    (let ((total (length tags))
+          (dots (reduce + 0 (map (cut string-count <> #\.) tags)))
+          (dashes (reduce + 0 (map (cut string-count <> #\-) tags)))
+          (underscores (reduce + 0 (map (cut string-count <> #\_) tags))))
+      (cond
+       ((>= dots (* total 0.35)) ".")
+       ((>= dashes (* total 0.8)) "-")
+       ((>= underscores (* total 0.8)) "_")
+       (else ""))))
+
+  (define delim-rx (regexp-quote (or delim (guess-delimiter))))
+  (define suffix-rx  (string-append (or suffix "") "$"))
+  (define prefix-rx (string-append "^" (or prefix "[^[:digit:]]*")))
+  (define pre-release-rx
+    (if pre-releases?
+        (string-append "(.*(" (string-join %pre-release-words "|") ").*)")
+        ""))
+
+  (define tag-rx
+    (string-append prefix-rx "([[:digit:]][^" delim-rx "[:punct:]]*"
+                   "(" delim-rx "[^[:punct:]" delim-rx "]+)"
+                   ;; If there are no delimiters, it could mean that the
+                   ;; version just contains one number (e.g., "2"), thus, use
+                   ;; "*" instead of "+" to match zero or more numbers.
+                   (if (string=? delim-rx "") "*" "+") ")"
+                   ;; We don't want the pre-release stuff (e.g., "-alpha") be
+                   ;; part of the first group; otherwise, the "-" in "-alpha"
+                   ;; might be interpreted as a delimiter, and thus replaced
+                   ;; with "."
+                   pre-release-rx suffix-rx))
+
+
+
+  (define (get-version tag)
+    (let ((tag-match (regexp-exec (make-regexp tag-rx) tag)))
+      (and=> (and tag-match
+                  (regexp-substitute/global
+                   #f delim-rx (match:substring tag-match 1)
+                   ;; If there were no delimiters, don't insert ".".
+                   'pre (if (string=? delim-rx "") "" ".") 'post))
+             (lambda (version)
+               (if pre-releases?
+                   (string-append version (match:substring tag-match 3))
+                   version)))))
+
+  (define (entry<? a b)
+    (eq? (version-compare (car a) (car b)) '<))
+
+  (stable-sort (filter-map (lambda (tag)
+                             (let ((version (get-version tag)))
+                               (and version (cons version tag))))
+                           tags)
+               entry<?))
+
+(define* (latest-tag url #:key prefix suffix delim pre-releases?)
+  "Return the latest version and corresponding tag available from the Git
+repository at URL."
+  (define (pre-release? tag)
+    (any (cut regexp-exec <> tag)
+         %pre-release-rx))
+
+  (let* ((tags (map (cut string-drop <> (string-length "refs/tags/"))
+                    (remote-refs url #:tags? #t)))
+         (versions->tags
+          (version-mapping (if pre-releases?
+                               tags
+                               (filter (negate pre-release?) tags))
+                           #:prefix prefix
+                           #:suffix suffix
+                           #:delim delim
+                           #:pre-releases? pre-releases?)))
+    (cond
+     ((null? tags)
+      (git-no-tags-error))
+     ((null? versions->tags)
+      (git-no-valid-tags-error))
+     (else
+      (match (last versions->tags)
+        ((version . tag)
+         (values version tag)))))))
+
+(define (latest-git-tag-version package)
+  "Given a PACKAGE, return the latest version of it, or #f if the latest version
+could not be determined."
+  (guard (c ((or (git-no-tags-error? c) (git-no-valid-tags-error? c))
+             (warning (or (package-field-location package 'source)
+                          (package-location package))
+                      (G_ "~a for ~a~%")
+                      (condition-message c)
+                      (package-name package))
+             #f)
+            ((eq? (exception-kind c) 'git-error)
+             (warning (or (package-field-location package 'source)
+                          (package-location package))
+                      (G_ "failed to fetch Git repository for ~a~%")
+                      (package-name package))
+             #f))
+    (let* ((source (package-source package))
+           (url (git-reference-url (origin-uri source)))
+           (property (cute assq-ref (package-properties package) <>)))
+      (latest-tag url
+                  #:prefix (property 'release-tag-prefix)
+                  #:suffix (property 'release-tag-suffix)
+                  #:delim (property 'release-tag-version-delimiter)
+                  #:pre-releases? (property 'accept-pre-releases?)))))
+
+(define (git-package? package)
+  "Return true if PACKAGE is hosted on a Git repository."
+  (match (package-source package)
+    ((? origin? origin)
+     (and (eq? (origin-method origin) git-fetch)
+          (git-reference? (origin-uri origin))))
+    (_ #f)))
+
+(define (latest-git-release package)
+  "Return an <upstream-source> for the latest release of PACKAGE."
+  (let* ((name (package-name package))
+         (old-version (package-version package))
+         (url (git-reference-url (origin-uri (package-source package))))
+         (new-version (latest-git-tag-version package)))
+
+    (and new-version
+         (upstream-source
+          (package name)
+          (version new-version)
+          (urls (list url))))))
+
+(define %generic-git-updater
+  (upstream-updater
+   (name 'generic-git)
+   (description "Updater for packages hosted on Git repositories")
+   (pred git-package?)
+   (latest latest-git-release)))