emacs: Add interface for system generations.

* emacs/guix-main.scm (system-generation-boot-parameters)
(system-generation-param-alist, system-generation-sexps): New procedures.
(entries): Add 'system-generation' entry type.
* emacs/guix-messages.el (guix-result-message): Use the same messages
  for 'generation' and 'system-generation' entry types.
* emacs/guix-ui-system-generation.el: New file.
* emacs.am (ELFILES): Add it.
* doc/emacs.texi (Emacs Commands): Document new commands.
* NEWS: Mention new interface.

6 files changed, 156 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index c35c7d67b9..0084394941 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ Please send Guix bug reports to bug-guix@gnu.org.
 
 ** Package management
 
+*** Emacs interface for system generations
 *** Emacs interface for hydra.gnu.org
 *** Changes in Emacs interface variables
 In the following names, BUFFER-TYPE means "info" or "list";
diff --git a/doc/emacs.texi b/doc/emacs.texi
index ea340b19fe..b2a3d473ab 100644
--- a/doc/emacs.texi
+++ b/doc/emacs.texi
@@ -191,6 +191,14 @@ date/time prompt,,, org, The Org Manual}).
 
 @end table
 
+Analogously on GuixSD you can also display system generations:
+
+@table @kbd
+@item M-x guix-system-generations
+@item M-x guix-last-system-generations
+@item M-x guix-system-generations-by-time
+@end table
+
 You can also invoke the @command{guix pull} command (@pxref{Invoking
 guix pull}) from Emacs using:
 
diff --git a/emacs.am b/emacs.am
index 85165b9368..d0d4dfb9bd 100644
--- a/emacs.am
+++ b/emacs.am
@@ -47,6 +47,7 @@ ELFILES =					\
   emacs/guix-ui.el				\
   emacs/guix-ui-package.el			\
   emacs/guix-ui-generation.el			\
+  emacs/guix-ui-system-generation.el		\
   emacs/guix-utils.el
 
 if HAVE_EMACS
diff --git a/emacs/guix-main.scm b/emacs/guix-main.scm
index 1199679975..236c882e3c 100644
--- a/emacs/guix-main.scm
+++ b/emacs/guix-main.scm
@@ -61,7 +61,8 @@
  (guix scripts lint)
  (guix scripts package)
  (guix scripts pull)
- (gnu packages))
+ (gnu packages)
+ (gnu system))
 
 (define-syntax-rule (first-or-false lst)
   (and (not (null? lst))
@@ -758,6 +759,38 @@ See 'entry-sexps' for details."
                                     params)))
     (map ->sexp generations)))
 
+(define system-generation-boot-parameters
+  (memoize
+   (lambda (profile generation)
+     "Return boot parameters for PROFILE's system GENERATION."
+     (let* ((gen-file   (generation-file-name profile generation))
+            (param-file (string-append gen-file "/parameters")))
+       (call-with-input-file param-file read-boot-parameters)))))
+
+(define (system-generation-param-alist profile)
+  "Return an alist of system generation parameters and procedures for
+PROFILE."
+  (append (generation-param-alist profile)
+          `((label       . ,(lambda (gen)
+                              (boot-parameters-label
+                               (system-generation-boot-parameters
+                                profile gen))))
+            (root-device . ,(lambda (gen)
+                              (boot-parameters-root-device
+                               (system-generation-boot-parameters
+                                profile gen))))
+            (kernel      . ,(lambda (gen)
+                              (boot-parameters-kernel
+                               (system-generation-boot-parameters
+                                profile gen)))))))
+
+(define (system-generation-sexps profile params search-type search-vals)
+  "Return an alist with information about system generations."
+  (let ((generations (find-generations profile search-type search-vals))
+        (->sexp (object-transformer (system-generation-param-alist profile)
+                                    params)))
+    (map ->sexp generations)))
+
 
 ;;; Getting package/output/generation entries (alists).
 
@@ -802,6 +835,9 @@ parameter/value pairs."
     ((generation)
      (generation-sexps profile params
                        search-type search-vals))
+    ((system-generation)
+     (system-generation-sexps profile params
+                              search-type search-vals))
     (else (entry-type-error entry-type))))
 
 
diff --git a/emacs/guix-messages.el b/emacs/guix-messages.el
index 9f6d833252..c4f15dcac2 100644
--- a/emacs/guix-messages.el
+++ b/emacs/guix-messages.el
@@ -186,7 +186,10 @@ Try \"M-x guix-search-by-name\"."
                             search-type search-vals)
   "Display an appropriate message after displaying ENTRIES."
   (let* ((type-spec (guix-assq-value guix-messages
-                                     entry-type search-type))
+                                     (if (eq entry-type 'system-generation)
+                                         'generation
+                                       entry-type)
+                                     search-type))
          (fun-or-count-spec (car type-spec)))
     (if (functionp fun-or-count-spec)
         (funcall fun-or-count-spec profile entries search-vals)
diff --git a/emacs/guix-ui-system-generation.el b/emacs/guix-ui-system-generation.el
new file mode 100644
index 0000000000..d79f3bceef
--- /dev/null
+++ b/emacs/guix-ui-system-generation.el
@@ -0,0 +1,105 @@
+;;; guix-ui-system-generation.el --- Interface for displaying system generations  -*- lexical-binding: t -*-
+
+;; Copyright © 2016 Alex Kost <alezost@gmail.com>
+
+;; 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This file provides an interface for displaying system generations
+;; in 'list' and 'info' buffers, and commands for working with them.
+
+;;; Code:
+
+(require 'cl-lib)
+(require 'guix-list)
+(require 'guix-ui)
+(require 'guix-ui-generation)
+(require 'guix-profiles)
+
+(guix-ui-define-entry-type system-generation)
+
+(defun guix-system-generation-get-display (search-type &rest search-values)
+  "Search for system generations and show results.
+See `guix-ui-get-entries' for the meaning of SEARCH-TYPE and
+SEARCH-VALUES."
+  (apply #'guix-list-get-display-entries
+         'system-generation
+         guix-system-profile
+         search-type search-values))
+
+
+;;; System generation 'info'
+
+(guix-ui-info-define-interface system-generation
+  :buffer-name "*Guix Generation Info*"
+  :format '((number format guix-generation-info-insert-number)
+            (label format (format))
+            (prev-number format (format))
+            (current format guix-generation-info-insert-current)
+            (path format (format guix-file))
+            (time format (time))
+            (root-device format (format))
+            (kernel format (format guix-file)))
+  :titles guix-generation-info-titles)
+
+
+;;; System generation 'list'
+
+;; FIXME It is better to make `guix-generation-list-shared-map' with
+;; common keys for both usual and system generations.
+(defvar guix-system-generation-list-mode-map
+  (copy-keymap guix-generation-list-mode-map)
+  "Keymap for `guix-system-generation-list-mode' buffers.")
+
+(guix-ui-list-define-interface system-generation
+  :buffer-name "*Guix Generation List*"
+  :format '((number nil 5 guix-list-sort-numerically-0 :right-align t)
+            (current guix-generation-list-get-current 10 t)
+            (label nil 40 t)
+            (time guix-list-get-time 20 t)
+            (path guix-list-get-file-path 30 t))
+  :titles guix-generation-list-titles
+  :sort-key '(number . t)
+  :marks '((delete . ?D)))
+
+
+;;; Interactive commands
+
+;;;###autoload
+(defun guix-system-generations ()
+  "Display information about system generations."
+  (interactive)
+  (guix-system-generation-get-display 'all))
+
+;;;###autoload
+(defun guix-last-system-generations (number)
+  "Display information about last NUMBER of system generations."
+  (interactive "nThe number of last generations: ")
+  (guix-system-generation-get-display 'last number))
+
+;;;###autoload
+(defun guix-system-generations-by-time (from to)
+  "Display information about system generations created between FROM and TO."
+  (interactive
+   (list (guix-read-date "Find generations (from): ")
+         (guix-read-date "Find generations (to): ")))
+  (guix-system-generation-get-display
+   'time (float-time from) (float-time to)))
+
+(provide 'guix-ui-system-generation)
+
+;;; guix-ui-system-generation.el ends here