installer: Add a help page.

* gnu/installer/newt/help.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* gnu/installer/record.scm (<installer>): Add 'help-menu' and 'help-page'
 fields,
 (installer-help-menu, installer-help-page): new exported procedures.
 * gnu/installer/newt.scm (init): Set the help line,
 (help-menu, help-page): new procedures used ...
 (newt-installer): ... here.
 * gnu/installer/newt/keymap.scm (run-layout-page): Add a context argument to
 differenciate the help context from the main one,
 (run-keymap-page): add a context argument and pass it to run-layout-page.
 * gnu/installer.scm (compute-keymap-step): Add a context argument and pass it
 to 'installer-keymap-page',
 (installer-steps): set the help menu and pass the appropriate context to
 compute-keymap-step calls,
 (guile-newt): update to revision 2.

6 files changed, 106 insertions, 26 deletions

diff --git a/gnu/installer.scm b/gnu/installer.scm
index 9f39191d54..084f437604 100644
--- a/gnu/installer.scm
+++ b/gnu/installer.scm
@@ -172,7 +172,7 @@ been performed at build time."
        (kmscon-update-keymap (default-keyboard-model)
                              layout variant))))
 
-(define* (compute-keymap-step)
+(define* (compute-keymap-step context)
   "Return a gexp that runs the keymap-page of INSTALLER and install the
 selected keymap."
   #~(lambda (current-installer)
@@ -184,7 +184,7 @@ selected keymap."
                                    "/share/X11/xkb/rules/base.xml")))
                (lambda (models layouts)
                  ((installer-keymap-page current-installer)
-                  layouts)))))
+                  layouts '#$context)))))
         (#$apply-keymap result)
         result)))
 
@@ -193,10 +193,15 @@ selected keymap."
                       #:locales-name "locales"
                       #:iso639-languages-name "iso639-languages"
                       #:iso3166-territories-name "iso3166-territories"))
-        (keymap-step (compute-keymap-step))
         (timezone-data #~(string-append #$tzdata
                                         "/share/zoneinfo/zone.tab")))
     #~(lambda (current-installer)
+        ((installer-help-menu current-installer)
+         (lambda ()
+           ((installer-help-page current-installer)
+            (lambda _
+              (#$(compute-keymap-step 'help)
+               current-installer)))))
         (list
          ;; Ask the user to choose a locale among those supported by
          ;; the glibc.  Install the selected locale right away, so that
@@ -238,7 +243,8 @@ selected keymap."
           (id 'keymap)
           (description (G_ "Keyboard mapping selection"))
           (compute (lambda _
-                     (#$keymap-step current-installer)))
+                     (#$(compute-keymap-step 'default)
+                      current-installer)))
           (configuration-formatter keyboard-layout->configuration))
 
          ;; Ask the user to input a hostname for the system.
@@ -295,8 +301,8 @@ selected keymap."
 (define guile-newt
   ;; Guile-Newt with 'form-watch-fd'.
   ;; TODO: Remove once a new release is out.
-  (let ((commit "b3c885d42cfac327d3531c9d064939514ce6bf12")
-        (revision "1"))
+  (let ((commit "c3cdeb0b53ac71aedabee669f57d44563c662446")
+        (revision "2"))
     (package
       (inherit (@ (gnu packages guile-xyz) guile-newt))
       (name "guile-newt")
@@ -309,7 +315,7 @@ selected keymap."
                  (file-name (git-file-name name version))
                  (sha256
                   (base32
-                   "02p0bi6c05699idgx6gfkljhqgi8zf09clhzx81i8wa064s70r1y")))))))
+                   "1gksd1lzgjjh1p9vczghg8jw995d22hm34kbsiv8rcryirv2xy09")))))))
 
 (define (installer-program)
   "Return a file-like object that runs the given INSTALLER."
diff --git a/gnu/installer/newt.scm b/gnu/installer/newt.scm
index 6c44b4acf6..7ac015eaad 100644
--- a/gnu/installer/newt.scm
+++ b/gnu/installer/newt.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2018, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -21,6 +21,7 @@
   #:use-module (gnu installer utils)
   #:use-module (gnu installer newt ethernet)
   #:use-module (gnu installer newt final)
+  #:use-module (gnu installer newt help)
   #:use-module (gnu installer newt hostname)
   #:use-module (gnu installer newt keymap)
   #:use-module (gnu installer newt locale)
@@ -44,7 +45,9 @@
 (define (init)
   (newt-init)
   (clear-screen)
-  (set-screen-size!))
+  (set-screen-size!)
+  (push-help-line
+   (format #f (G_ "Press <F1> for help."))))
 
 (define (exit)
   (newt-finish)
@@ -91,8 +94,8 @@ problem. The backtrace is displayed below. Please report it by email to \
 (define (menu-page steps)
   (run-menu-page steps))
 
-(define* (keymap-page layouts)
-  (run-keymap-page layouts))
+(define* (keymap-page layouts context)
+  (run-keymap-page layouts #:context context))
 
 (define (network-page)
   (run-network-page))
@@ -109,6 +112,12 @@ problem. The backtrace is displayed below. Please report it by email to \
 (define (services-page)
   (run-services-page))
 
+(define (help-menu menu-proc)
+  (newt-set-help-callback menu-proc))
+
+(define (help-page keyboard-layout-selection)
+  (run-help-page keyboard-layout-selection))
+
 (define newt-installer
   (installer
    (name 'newt)
@@ -125,4 +134,6 @@ problem. The backtrace is displayed below. Please report it by email to \
    (user-page user-page)
    (partition-page partition-page)
    (services-page services-page)
-   (welcome-page welcome-page)))
+   (welcome-page welcome-page)
+   (help-menu help-menu)
+   (help-page help-page)))
diff --git a/gnu/installer/newt/help.scm b/gnu/installer/newt/help.scm
new file mode 100644
index 0000000000..8d85832dc8
--- /dev/null
+++ b/gnu/installer/newt/help.scm
@@ -0,0 +1,43 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2020 Mathieu Othacehe <m.othacehe@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 GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu installer newt help)
+  #:use-module (gnu installer steps)
+  #:use-module (gnu installer newt page)
+  #:use-module (guix i18n)
+  #:use-module (ice-9 match)
+  #:use-module (newt)
+  #:export (run-help-page))
+
+(define (run-help-page keyboard-layout-selection)
+  "Run a help page allowing to change the keyboard layout"
+  (let* ((items
+          (list
+           (cons (G_ "Change keyboard layout") keyboard-layout-selection)))
+         (result
+          (run-listbox-selection-page
+           #:info-text (G_ "This is the help menu, please choose an action.")
+           #:title (G_ "Installation help")
+           #:listbox-items items
+           #:listbox-item->text car
+           #:sort-listbox-items? #f
+           #:button-text (G_ "Continue"))))
+    (match result
+      ((_ . proc)
+       (proc))
+      (_ #f))))
diff --git a/gnu/installer/newt/keymap.scm b/gnu/installer/newt/keymap.scm
index 2908ba7f0e..0147a0b9d5 100644
--- a/gnu/installer/newt/keymap.scm
+++ b/gnu/installer/newt/keymap.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2018, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -33,20 +33,32 @@
   #:export (run-keymap-page
             keyboard-layout->configuration))
 
-(define (run-layout-page layouts layout->text)
+(define (run-layout-page layouts layout->text context)
   (let ((title (G_ "Layout")))
     (run-listbox-selection-page
      #:title title
-     #:info-text (G_ "Please choose your keyboard layout.")
+     #:info-text
+     (case context
+       ((help) (G_ "Please choose your keyboard layout. \
+It will only be used during the installation process."))
+       (else (G_ "Please choose your keyboard layout. \
+It will be used during the install process, and for the installed system. \
+You can switch to different layout at any time from the help menu.")))
      #:listbox-items layouts
      #:listbox-item->text layout->text
      #:sort-listbox-items? #f
-     #:button-text (G_ "Exit")
+     #:button-text
+     (case context
+       ((help) (G_ "Continue"))
+       (else (G_ "Exit")))
      #:button-callback-procedure
-     (lambda _
-       (raise
-        (condition
-         (&installer-step-abort)))))))
+     (case context
+       ((help) (const #t))
+       (else
+        (lambda _
+          (raise
+           (condition
+            (&installer-step-abort)))))))))
 
 (define (run-variant-page variants variant->text)
   (let ((title (G_ "Variant")))
@@ -100,7 +112,7 @@
          variants))
     (cut append <> <>)))
 
-(define* (run-keymap-page layouts)
+(define* (run-keymap-page layouts #:key (context #f))
   "Run a page asking the user to select a keyboard layout and variant. LAYOUTS
 is a list of supported X11-KEYMAP-LAYOUT. Return a list of two elements, the
 names of the selected keyboard layout and variant."
@@ -114,7 +126,8 @@ names of the selected keyboard layout and variant."
           (sort-layouts layouts)
           (lambda (layout)
             (gettext (x11-keymap-layout-description layout)
-                     "xkeyboard-config"))))))
+                     "xkeyboard-config"))
+          context))))
      ;; Propose the user to select a variant among those supported by the
      ;; previously selected layout.
      (installer-step
diff --git a/gnu/installer/record.scm b/gnu/installer/record.scm
index edf73b6215..78acf50c63 100644
--- a/gnu/installer/record.scm
+++ b/gnu/installer/record.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2018, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -37,7 +37,9 @@
             installer-user-page
             installer-partition-page
             installer-services-page
-            installer-welcome-page))
+            installer-welcome-page
+            installer-help-menu
+            installer-help-page))
 
 
 ;;;
@@ -61,7 +63,7 @@
   (exit-error installer-exit-error)
   ;; procedure void -> void
   (final-page installer-final-page)
-  ;; procedure (layouts) -> (list layout variant)
+  ;; procedure (layouts context) -> (list layout variant)
   (keymap-page installer-keymap-page)
   ;; procedure: (#:key supported-locales iso639-languages iso3166-territories)
   ;; -> glibc-locale
@@ -81,4 +83,8 @@
   ;; procedure void -> void
   (services-page installer-services-page)
   ;; procedure (logo) -> void
-  (welcome-page installer-welcome-page))
+  (welcome-page installer-welcome-page)
+  ;; procedure (menu-proc) -> void
+  (help-menu installer-help-menu)
+  ;; procedure (keyboard-layout-selection) -> void
+  (help-page installer-help-page))
diff --git a/gnu/local.mk b/gnu/local.mk
index bc51fbb33b..77f9de2440 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -671,6 +671,7 @@ INSTALLER_MODULES =                             \
 						\
   %D%/installer/newt/ethernet.scm		\
   %D%/installer/newt/final.scm  		\
+  %D%/installer/newt/help.scm			\
   %D%/installer/newt/hostname.scm		\
   %D%/installer/newt/keymap.scm			\
   %D%/installer/newt/locale.scm			\