installer: Add an "Edit" button on the final page.

Fixes <https://bugs.gnu.org/36885>.
Reported by <lukasbf@tutanota.com>.

* gnu/installer/newt/page.scm (edit-file): New procedure.
(run-file-textbox-page): Add #:edit-button? and #:editor-locale
parameters.  Remove 'file-text' and add 'edit-button', and add it
to the horizontal stacked grid when EXIT-BUTTON? is true.  Wrap
body in 'loop'.  Handle case where ARGUMENT is EDIT-BUTTON by calling
'loop'.
* gnu/installer/newt/final.scm (run-config-display-page): Add #:locale
parameter.  Pass #:edit-button? and #:editor-locale to
'run-file-textbox-page'.
(run-final-page): Pass LOCALE to 'run-config-display-page'.

2 files changed, 56 insertions, 30 deletions

diff --git a/gnu/installer/newt/final.scm b/gnu/installer/newt/final.scm
index e375282613..061bcd3f78 100644
--- a/gnu/installer/newt/final.scm
+++ b/gnu/installer/newt/final.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
-;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -36,7 +36,7 @@
       (string-drop file (string-length prefix))
       file))
 
-(define (run-config-display-page)
+(define* (run-config-display-page #:key locale)
   (let ((width (%configuration-file-width))
         (height (nearest-exact-integer
                  (/ (screen-rows) 2))))
@@ -50,6 +50,8 @@ This will take a few minutes.")
                          (strip-prefix (%installer-configuration-file)))
      #:title (G_ "Configuration file")
      #:file (%installer-configuration-file)
+     #:edit-button? #t
+     #:editor-locale locale
      #:info-textbox-width width
      #:file-textbox-width width
      #:file-textbox-height height
@@ -95,7 +97,7 @@ last step, or restart the installer.")))
           (with-mounted-partitions
            user-partitions
            (configuration->file configuration)
-           (run-config-display-page)
+           (run-config-display-page #:locale locale)
            (run-install-shell locale #:users users))))
     (if install-ok?
         (run-install-success-page)
diff --git a/gnu/installer/newt/page.scm b/gnu/installer/newt/page.scm
index 630efde9cc..bff5fae4e6 100644
--- a/gnu/installer/newt/page.scm
+++ b/gnu/installer/newt/page.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
-;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2019 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -541,6 +541,17 @@ ITEMS when 'Ok' is pressed."
         (lambda ()
           (destroy-form-and-pop form))))))
 
+(define* (edit-file file #:key locale)
+  "Spawn an editor for FILE."
+  (clear-screen)
+  (newt-suspend)
+  ;; Use Nano because it syntax-highlights Scheme by default.
+  ;; TODO: Add a menu to choose an editor?
+  (run-shell-command (string-append "/run/current-system/profile/bin/nano "
+                                    file)
+                     #:locale locale)
+  (newt-resume))
+
 (define* (run-file-textbox-page #:key
                                 info-text
                                 title
@@ -549,6 +560,8 @@ ITEMS when 'Ok' is pressed."
                                 (file-textbox-width 50)
                                 (file-textbox-height 30)
                                 (exit-button? #t)
+                                (edit-button? #f)
+                                (editor-locale #f)
                                 (ok-button-callback-procedure
                                  (const #t))
                                 (exit-button-callback-procedure
@@ -557,7 +570,6 @@ ITEMS when 'Ok' is pressed."
           (make-reflowed-textbox -1 -1 info-text
                                  info-textbox-width
                                  #:flags FLAG-BORDER))
-         (file-text (read-all file))
          (file-textbox
           (make-textbox -1 -1
                         file-textbox-width
@@ -565,6 +577,8 @@ ITEMS when 'Ok' is pressed."
                         (logior FLAG-SCROLL FLAG-BORDER)))
          (ok-button (make-button -1 -1 (G_ "OK")))
          (exit-button (make-button -1 -1 (G_ "Exit")))
+         (edit-button (and edit-button?
+                           (make-button -1 -1 (G_ "Edit"))))
          (grid (vertically-stacked-grid
                 GRID-ELEMENT-COMPONENT info-textbox
                 GRID-ELEMENT-COMPONENT file-textbox
@@ -572,32 +586,42 @@ ITEMS when 'Ok' is pressed."
                 (apply
                  horizontal-stacked-grid
                  GRID-ELEMENT-COMPONENT ok-button
-                 `(,@(if exit-button?
+                 `(,@(if edit-button?
+                         (list GRID-ELEMENT-COMPONENT edit-button)
+                         '())
+                   ,@(if exit-button?
                          (list GRID-ELEMENT-COMPONENT exit-button)
                          '())))))
          (form (make-form)))
 
-    (set-textbox-text file-textbox
-                      (receive (_w _h text)
-                          (reflow-text file-text
-                                       file-textbox-width
-                                       0 0)
-                        text))
-    (add-form-to-grid grid form #t)
-    (make-wrapped-grid-window grid title)
-
-    (receive (exit-reason argument)
-        (run-form form)
-      (dynamic-wind
-        (const #t)
-        (lambda ()
-          (case exit-reason
-            ((exit-component)
-             (cond
-              ((components=? argument ok-button)
-               (ok-button-callback-procedure))
-              ((and exit-button?
-                    (components=? argument exit-button))
-               (exit-button-callback-procedure))))))
-        (lambda ()
-          (destroy-form-and-pop form))))))
+    (let loop ()
+      (set-textbox-text file-textbox
+                        (receive (_w _h text)
+                            (reflow-text (read-all file)
+                                         file-textbox-width
+                                         0 0)
+                          text))
+
+      (add-form-to-grid grid form #t)
+      (make-wrapped-grid-window grid title)
+
+      (receive (exit-reason argument)
+          (run-form form)
+        (dynamic-wind
+          (const #t)
+          (lambda ()
+            (case exit-reason
+              ((exit-component)
+               (cond
+                ((components=? argument ok-button)
+                 (ok-button-callback-procedure))
+                ((and exit-button?
+                      (components=? argument exit-button))
+                 (exit-button-callback-procedure))
+                ((and edit-button?
+                      (components=? argument edit-button))
+                 (edit-file file))))))
+          (lambda ()
+            (if (components=? argument edit-button)
+                (loop)
+                (destroy-form-and-pop form))))))))