[bug#60521] [PATCH-v4] home: Add home-dotfiles-service.

[Giacomo Leidi]

* gnu/home/services.scm (dotfiles-for-app): New variable;
(home-dotfiles-configuration): new variable;
(home-dotfiles-service-type): new variable.
* doc/guix.texi: Document it.
---
 doc/guix.texi         | 108 ++++++++++++++++++++++++++++++++++++++++++
 gnu/home/services.scm |  78 ++++++++++++++++++++++++++++++
 2 files changed, 186 insertions(+)

diff --git a/doc/guix.texi b/doc/guix.texi
index 6105195bd9..87f0fdf8a1 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -43153,6 +43153,114 @@ Essential Home Services
 read-only home.  Feel free to experiment and share your results.
 @end defvar
 
+It is often the case that Guix Home users already have a setup for versioning
+their user configuration files (also known as @emph{dotfiles}) in a single
+directory, and some way of automatically deploy changes to their user home.
+
+The @code{home-dotfiles-service-type} is designed to ease the way into using
+Guix Home for this kind of users, allowing them to point the service to their
+dotfiles directory, which must follow the layout suggested by
+@uref{https://www.gnu.org/software/stow/, GNU Stow},
+and have their dotfiles automatically deployed to their user home, without
+migrating them to Guix native configurations.
+
+The dotfiles directory layout is expected to be structured as follows. Please
+keep in mind that it is advisable to keep your dotfiles directories under
+version control, for example in the same repository where you'd track your
+Guix Home configuration.
+
+@example
+~$ tree -a .dotfiles/
+.dotfiles/
+├── git
+│   └── .gitconfig
+├── gpg
+│   └── .gnupg
+│       ├── gpg-agent.conf
+│       └── gpg.conf
+├── guile
+│   └── .guile
+├── guix
+│   └── .config
+│       └── guix
+│           └── channels.scm
+├── nix
+│   ├── .config
+│   │   └── nixpkgs
+│   │       └── config.nix
+│   └── .nix-channels
+├── tmux
+│   └── .tmux.conf
+└── vim
+    └── .vimrc
+
+13 directories, 10 files
+@end example
+
+For an informal specification please refer to the Stow manual
+(@pxref{Top,,, stow, Introduction}). A suitable configuration would then
+be:
+
+@lisp
+(use-modules (guix utils))
+
+(home-environment
+
+  [...]
+
+  (services
+    (service home-dotfiles-service-type
+             (home-dotfiles-configuration
+               (directories
+                 (list (string-append (current-source-directory)
+                                      "/.dotfiles")))))))
+@end lisp
+
+The expected home directory state would be:
+
+@example
+.
+├── .config
+│   ├── guix
+│   │   └── channels.scm
+│   └── nixpkgs
+│       └── config.nix
+├── .gitconfig
+├── .gnupg
+│   ├── gpg-agent.conf
+│   └── gpg.conf
+├── .guile
+├── .nix-channels
+├── .tmux.conf
+└── .vimrc
+@end example
+
+@defvar home-dotfiles-service-type
+Return a service which is very similiar to @code{home-files-service-type}
+(and actually extends it), but designed to ease the way into using Guix
+Home for users that already track their dotfiles under some kind of version
+control.  This service allows users to point Guix Home to their dotfiles
+directory and have their file automatically deployed to their home directory
+just like Stow would, without migrating all of their dotfiles to Guix native
+configurations.
+@end defvar
+
+@deftp {Data Type} home-dotfiles-configuration
+Available @code{home-dotfiles-configuration} fields are:
+
+@table @asis
+@item @code{directories} (type: list-of-strings)
+The list of dotfiles directories where @code{home-dotfiles-service-type} will
+look for application dotfiles.
+
+@item @code{exclude} (default: @code{'(".*~" ".*\\.swp" "\\.gitignore")})
+The list of file patterns @code{home-dotfiles-service-type} will exclude while
+visiting @code{directories}.
+
+@end table
+
+@end deftp
+
 @defvar home-xdg-configuration-files-service-type
 The service is very similar to @code{home-files-service-type} (and
 actually extends it), but used for defining files, which will go to
diff --git a/gnu/home/services.scm b/gnu/home/services.scm
index 8d53f2f4d3..8a74052b5a 100644
--- a/gnu/home/services.scm
+++ b/gnu/home/services.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2021-2023 Andrew Tropin <andrew@trop.in>
 ;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
 ;;; Copyright © 2022-2023 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2023 Giacomo Leidi <goodoldpaul@autistici.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -22,6 +23,7 @@ (define-module (gnu home services)
   #:use-module (gnu services)
   #:use-module ((gnu packages package-management) #:select (guix))
   #:use-module ((gnu packages base) #:select (coreutils))
+  #:use-module (guix build utils)
   #:use-module (guix channels)
   #:use-module (guix monads)
   #:use-module (guix store)
@@ -34,15 +36,24 @@ (define-module (gnu home services)
   #:use-module (guix i18n)
   #:use-module (guix modules)
   #:use-module (guix memoization)
+  #:use-module (guix records)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
+  #:use-module (ice-9 ftw)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 regex)
+  #:use-module (ice-9 string-fun)
   #:use-module (ice-9 vlist)
 
   #:export (home-service-type
             home-profile-service-type
             home-environment-variables-service-type
             home-files-service-type
+            home-dotfiles-service-type
+            home-dotfiles-configuration
+            home-dotfiles-configuration?
+            home-dotfiles-configuration-directories
+            home-dotfiles-configuration-excluded
             home-xdg-configuration-files-service-type
             home-xdg-data-files-service-type
             home-run-on-first-login-service-type
@@ -354,6 +365,73 @@ (define home-files-service-type
                 (description "Files that will be put in
 @file{~/.guix-home/files}, and further processed during activation.")))
 
+(define %home-dotfiles-excluded
+  '(".*~"
+    ".*\\.swp"
+    "\\.gitignore"))
+
+(define-record-type* <home-dotfiles-configuration>
+  home-dotfiles-configuration make-home-dotfiles-configuration
+  home-dotfiles-configuration?
+  (directories       home-dotfiles-configuration-directories       ;list of 
strings
+                     (default '()))
+  (excluded          home-dotfiles-configuration-excluded          ;list of 
strings
+                     (default %home-dotfiles-excluded)))
+
+(define* (import-dotfiles directory excluded)
+  "Return a list of objects compatible with @code{home-files-service-type}'s
+value.  Each object is a pair where the first element is the relative path
+of a file and the second is a gexp representing the file content.  Objects are
+generated by recursively visiting DIRECTORY and mapping its contents to the
+user's home directory, excluding files that match any of the patterns in 
EXCLUDED."
+  (define filtered
+    (find-files directory
+                (lambda (file stat)
+                  (not (string-match
+                        (string-append
+                         "^.*(" (string-join excluded "|") ")$") file)))))
+  (define (strip file)
+     (string-drop file (+ 1 (string-length directory))))
+  (define (format file)
+    (string-append "home-dotfiles-"
+                   (string-replace-substring file "/" "-")))
+
+  (map (lambda (file)
+        (let* ((stripped (strip file)))
+          (list stripped
+                (local-file file (format stripped)))))
+       filtered))
+
+(define (home-dotfiles-configuration->files config)
+   "Return a list of objects compatible with @code{home-files-service-type}'s
+value, generated following GNU Stow's algorithm for each of the
+directories in CONFIG, excluding files that match any of the patterns 
configured."
+   (define (directory-contents directories)
+     (append-map
+      (lambda (directory)
+        (map
+         (lambda (content)
+           (with-directory-excursion directory
+               (canonicalize-path content)))
+         (scandir directory
+           (lambda (name)
+             (not (member name '("." "..")))))))
+      directories))
+   (append-map
+    (lambda (app)
+      (import-dotfiles app (home-dotfiles-configuration-excluded config)))
+    (directory-contents
+     (home-dotfiles-configuration-directories config))))
+
+(define-public home-dotfiles-service-type
+  (service-type (name 'home-dotfiles)
+                (extensions
+                 (list (service-extension home-files-service-type
+                                          home-dotfiles-configuration->files)))
+                (default-value (home-dotfiles-configuration))
+                (description "Files that will be put in the user's home 
directory
+following GNU Stow's algorithm, and further processed during activation.")))
+
 (define xdg-configuration-files-directory ".config")
 
 (define (xdg-configuration-files files)

base-commit: eeb71d778f149834015858467fbeeb1276d96d1d
-- 
2.41.0