home-services: Add most essential home services.

* gnu/home-services.scm (home-service-type, home-profile-service-type)
(home-environment-variables-service-type, home-files-service-type)
(home-run-on-first-login-service-type, home-activation-service-type): New
variables.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add home-services.scm.

Signed-off-by: Oleg Pykhalov <go.wigust@gmail.com>

2 files changed, 370 insertions, 0 deletions

diff --git a/gnu/home-services.scm b/gnu/home-services.scm
new file mode 100644
index 0000000000..4a6458abec
--- /dev/null
+++ b/gnu/home-services.scm
@@ -0,0 +1,368 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2021 Andrew Tropin <andrew@trop.in>
+;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
+;;;
+;;; 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 home-services)
+  #:use-module (gnu services)
+  #:use-module (guix channels)
+  #:use-module (guix monads)
+  #:use-module (guix store)
+  #:use-module (guix gexp)
+  #:use-module (guix profiles)
+  #:use-module (guix sets)
+  #:use-module (guix ui)
+  #:use-module (guix discovery)
+  #:use-module (guix diagnostics)
+
+  #:use-module (srfi srfi-1)
+  #:use-module (ice-9 match)
+
+  #:export (home-service-type
+            home-profile-service-type
+            home-environment-variables-service-type
+            home-files-service-type
+            home-run-on-first-login-service-type
+            home-activation-service-type)
+
+  #:re-export (service
+               service-type
+               service-extension))
+
+;;; Comment:
+;;;
+;;; This module is similar to (gnu system services) module, but
+;;; provides Home Services, which are supposed to be used for building
+;;; home-environment.
+;;;
+;;; Home Services use the same extension as System Services.  Consult
+;;; (gnu system services) module or manual for more information.
+;;;
+;;; home-service-type is a root of home services DAG.
+;;;
+;;; home-profile-service-type is almost the same as profile-service-type, at least
+;;; for now.
+;;;
+;;; home-environment-variables-service-type generates a @file{setup-environment}
+;;; shell script, which is expected to be sourced by login shell or other program,
+;;; which starts early and spawns all other processes.  Home services for shells
+;;; automatically add code for sourcing this file, if person do not use those home
+;;; services they have to source this script manually in their's shell *profile
+;;; file (details described in the manual).
+;;;
+;;; home-files-service-type is similar to etc-service-type, but doesn't extend
+;;; home-activation, because deploy mechanism for config files is pluggable and
+;;; can be different for different home environments: The default one is called
+;;; symlink-manager (will be introudced in a separate patch series), which creates
+;;; links for various dotfiles (like $XDG_CONFIG_HOME/$APP/...) to store, but is
+;;; possible to implement alternative approaches like read-only home from Julien's
+;;; guix-home-manager.
+;;;
+;;; home-run-on-first-login-service-type provides an @file{on-first-login} guile
+;;; script, which runs provided gexps once, when user makes first login.  It can
+;;; be used to start user's Shepherd and maybe some other process.  It relies on
+;;; assumption that /run/user/$UID will be created on login by some login
+;;; manager (elogind for example).
+;;;
+;;; home-activation-service-type provides an @file{activate} guile script, which
+;;; do three main things:
+;;;
+;;; - Sets environment variables to the values declared in
+;;; @file{setup-environment} shell script.  It's necessary, because user can set
+;;; for example XDG_CONFIG_HOME and it should be respected by activation gexp of
+;;; symlink-manager.
+;;;
+;;; - Sets GUIX_NEW_HOME and possibly GUIX_OLD_HOME vars to paths in the store.
+;;; Later those variables can be used by activation gexps, for example by
+;;; symlink-manager or run-on-change services.
+;;;
+;;; - Run all activation gexps provided by other home services.
+;;;
+;;; Code:
+
+
+(define (home-derivation entries mextensions)
+  "Return as a monadic value the derivation of the 'home'
+directory containing the given entries."
+  (mlet %store-monad ((extensions (mapm/accumulate-builds identity
+                                                          mextensions)))
+    (lower-object
+     (file-union "home" (append entries (concatenate extensions))))))
+
+(define home-service-type
+  ;; This is the ultimate service type, the root of the home service
+  ;; DAG.  The service of this type is extended by monadic name/item
+  ;; pairs.  These items end up in the "home-environment directory" as
+  ;; returned by 'home-environment-derivation'.
+  (service-type (name 'home)
+                (extensions '())
+                (compose identity)
+                (extend home-derivation)
+                (default-value '())
+                (description
+                 "Build the home environment top-level directory,
+which in turn refers to everything the home environment needs: its
+packages, configuration files, activation script, and so on.")))
+
+(define (packages->profile-entry packages)
+  "Return a system entry for the profile containing PACKAGES."
+  ;; XXX: 'mlet' is needed here for one reason: to get the proper
+  ;; '%current-target' and '%current-target-system' bindings when
+  ;; 'packages->manifest' is called, and thus when the 'package-inputs'
+  ;; etc. procedures are called on PACKAGES.  That way, conditionals in those
+  ;; inputs see the "correct" value of these two parameters.  See
+  ;; <https://issues.guix.gnu.org/44952>.
+  (mlet %store-monad ((_ (current-target-system)))
+    (return `(("profile" ,(profile
+                           (content (packages->manifest
+                                     (map identity
+                                     ;;(options->transformation transformations)
+                                     (delete-duplicates packages eq?))))))))))
+
+;; MAYBE: Add a list of transformations for packages.  It's better to
+;; place it in home-profile-service-type to affect all profile
+;; packages and prevent conflicts, when other packages relies on
+;; non-transformed version of package.
+(define home-profile-service-type
+  (service-type (name 'home-profile)
+                (extensions
+                 (list (service-extension home-service-type
+                                          packages->profile-entry)))
+                (compose concatenate)
+                (extend append)
+                (description
+                 "This is the @dfn{home profile} and can be found in
+@file{~/.guix-home/profile}.  It contains packages and
+configuration files that the user has declared in their
+@code{home-environment} record.")))
+
+(define (environment-variables->setup-environment-script vars)
+  "Return a file that can be sourced by a POSIX compliant shell which
+initializes the environment.  The file will source the home
+environment profile, set some default environment variables, and set
+environment variables provided in @code{vars}.  @code{vars} is a list
+of pairs (@code{(key . value)}), @code{key} is a string and
+@code{value} is a string or gexp.
+
+If value is @code{#f} variable will be omitted.
+If value is @code{#t} variable will be just exported.
+For any other, value variable will be set to the @code{value} and
+exported."
+  (define (warn-about-duplicate-defenitions)
+    (fold
+     (lambda (x acc)
+       (when (equal? (car x) (car acc))
+         (warning
+          (G_ "duplicate definition for `~a' environment variable ~%") (car x)))
+       x)
+     (cons "" "")
+     (sort vars (lambda (a b)
+                  (string<? (car a) (car b))))))
+
+  (warn-about-duplicate-defenitions)
+  (with-monad
+   %store-monad
+   (return
+    `(("setup-environment"
+       ;; TODO: It's necessary to source ~/.guix-profile too
+       ;; on foreign distros
+       ,(apply mixed-text-file "setup-environment"
+               "\
+HOME_ENVIRONMENT=$HOME/.guix-home
+GUIX_PROFILE=\"$HOME_ENVIRONMENT/profile\"
+PROFILE_FILE=\"$HOME_ENVIRONMENT/profile/etc/profile\"
+[ -f $PROFILE_FILE ] && . $PROFILE_FILE
+
+case $XDG_DATA_DIRS in
+  *$HOME_ENVIRONMENT/profile/share*) ;;
+  *) export XDG_DATA_DIRS=$HOME_ENVIRONMENT/profile/share:$XDG_DATA_DIRS ;;
+esac
+case $MANPATH in
+  *$HOME_ENVIRONMENT/profile/share/man*) ;;
+  *) export MANPATH=$HOME_ENVIRONMENT/profile/share/man:$MANPATH
+esac
+case $INFOPATH in
+  *$HOME_ENVIRONMENT/profile/share/info*) ;;
+  *) export INFOPATH=$HOME_ENVIRONMENT/profile/share/info:$INFOPATH ;;
+esac
+case $XDG_CONFIG_DIRS in
+  *$HOME_ENVIRONMENT/profile/etc/xdg*) ;;
+  *) export XDG_CONFIG_DIRS=$HOME_ENVIRONMENT/profile/etc/xdg:$XDG_CONFIG_DIRS ;;
+esac
+case $XCURSOR_PATH in
+  *$HOME_ENVIRONMENT/profile/share/icons*) ;;
+  *) export XCURSOR_PATH=$HOME_ENVIRONMENT/profile/share/icons:$XCURSOR_PATH ;;
+esac
+
+"
+
+               (append-map
+                (match-lambda
+                  ((key . #f)
+                   '())
+                  ((key . #t)
+                   (list "export " key "\n"))
+                  ((key . value)
+                   (list "export " key "=" value "\n")))
+                vars)))))))
+
+(define home-environment-variables-service-type
+  (service-type (name 'home-environment-variables)
+                (extensions
+                 (list (service-extension
+                        home-service-type
+                        environment-variables->setup-environment-script)))
+                (compose concatenate)
+                (extend append)
+                (default-value '())
+                (description "Set the environment variables.")))
+
+(define (files->files-directory files)
+  "Return a @code{files} directory that contains FILES."
+  (define (assert-no-duplicates files)
+    (let loop ((files files)
+               (seen (set)))
+      (match files
+        (() #t)
+        (((file _) rest ...)
+         (when (set-contains? seen file)
+           (raise (formatted-message (G_ "duplicate '~a' entry for files/")
+                                     file)))
+         (loop rest (set-insert file seen))))))
+
+  ;; Detect duplicates early instead of letting them through, eventually
+  ;; leading to a build failure of "files.drv".
+  (assert-no-duplicates files)
+
+  (file-union "files" files))
+
+(define (files-entry files)
+  "Return an entry for the @file{~/.guix-home/files}
+directory containing FILES."
+  (with-monad %store-monad
+    (return `(("files" ,(files->files-directory files))))))
+
+(define home-files-service-type
+  (service-type (name 'home-files)
+                (extensions
+                 (list (service-extension home-service-type
+                                          files-entry)))
+                (compose concatenate)
+                (extend append)
+                (default-value '())
+                (description "Configuration files for programs that
+will be put in @file{~/.guix-home/files}.")))
+
+(define (compute-on-first-login-script _ gexps)
+  (gexp->script
+   "on-first-login"
+   #~(let* ((xdg-runtime-dir (or (getenv "XDG_RUNTIME_DIR")
+                                 (format #f "/run/user/~a" (getuid))))
+            (flag-file-path (string-append
+                             xdg-runtime-dir "/on-first-login-executed"))
+            (touch (lambda (file-name)
+                     (call-with-output-file file-name (const #t)))))
+       ;; XDG_RUNTIME_DIR dissapears on logout, that means such trick
+       ;; allows to launch on-first-login script on first login only
+       ;; after complete logout/reboot.
+       (when (not (file-exists? flag-file-path))
+         (begin #$@gexps (touch flag-file-path))))))
+
+(define (on-first-login-script-entry m-on-first-login)
+  "Return, as a monadic value, an entry for the on-first-login script
+in the home environment directory."
+  (mlet %store-monad ((on-first-login m-on-first-login))
+        (return `(("on-first-login" ,on-first-login)))))
+
+(define home-run-on-first-login-service-type
+  (service-type (name 'home-run-on-first-login)
+                (extensions
+                 (list (service-extension
+                        home-service-type
+                        on-first-login-script-entry)))
+                (compose identity)
+                (extend compute-on-first-login-script)
+                (default-value #f)
+                (description "Run gexps on first user login.  Can be
+extended with one gexp.")))
+
+
+(define (compute-activation-script init-gexp gexps)
+  (gexp->script
+   "activate"
+   #~(let* ((he-init-file (lambda (he) (string-append he "/setup-environment")))
+            (he-path (string-append (getenv "HOME") "/.guix-home"))
+            (new-home-env (getenv "GUIX_NEW_HOME"))
+            (new-home (or new-home-env
+                          ;; Path of the activation file if called interactively
+                          (dirname (car (command-line)))))
+            (old-home-env (getenv "GUIX_OLD_HOME"))
+            (old-home (or old-home-env
+                          (if (file-exists? (he-init-file he-path))
+                              (readlink he-path)
+                              #f))))
+       (if (file-exists? (he-init-file new-home))
+           (let* ((port   ((@ (ice-9 popen) open-input-pipe)
+                           (format #f "source ~a && env"
+                                   (he-init-file new-home))))
+                  (result ((@ (ice-9 rdelim) read-delimited) "" port))
+                  (vars (map (lambda (x)
+                               (let ((si (string-index x #\=)))
+                                 (cons (string-take x si)
+                                       (string-drop x (1+ si)))))
+                             ((@ (srfi srfi-1) remove)
+                              string-null?
+                              (string-split result #\newline)))))
+             (close-port port)
+             (map (lambda (x) (setenv (car x) (cdr x))) vars)
+
+             (setenv "GUIX_NEW_HOME" new-home)
+             (setenv "GUIX_OLD_HOME" old-home)
+
+             #$@gexps
+
+             ;; Do not unset env variable if it was set outside.
+             (unless new-home-env (setenv "GUIX_NEW_HOME" #f))
+             (unless old-home-env (setenv "GUIX_OLD_HOME" #f)))
+           (format #t "\
+Activation script was either called or loaded by file from this direcotry:
+~a
+It doesn't seem that home environment is somewhere around.
+Make sure that you call ./activate by symlink from -home store item.\n"
+                   new-home)))))
+
+(define (activation-script-entry m-activation)
+  "Return, as a monadic value, an entry for the activation script
+in the home environment directory."
+  (mlet %store-monad ((activation m-activation))
+    (return `(("activate" ,activation)))))
+
+(define home-activation-service-type
+  (service-type (name 'home-activation)
+                (extensions
+                 (list (service-extension
+                        home-service-type
+                        activation-script-entry)))
+                (compose identity)
+                (extend compute-activation-script)
+                (default-value #f)
+                (description "Run gexps to activate the current
+generation of home environment and update the state of the home
+directory.  @command{activate} script automatically called during
+reconfiguration or generation switching.  This service can be extended
+with one gexp, but many times, and all gexps must be idempotent.")))
+
diff --git a/gnu/local.mk b/gnu/local.mk
index 2a56c4a9e2..73190b7fad 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -44,6 +44,7 @@
 # Copyright © 2021 Arun Isaac <arunisaac@systemreboot.net>
 # Copyright © 2021 Sharlatan Hellseher <sharlatanus@gmail.com>
 # Copyright © 2021 Dmitry Polyakov <polyakov@liltechdude.xyz>
+# Copyright © 2021 Andrew Tropin <andrew@trop.in>
 #
 # This file is part of GNU Guix.
 #
@@ -72,6 +73,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/bootloader/u-boot.scm                     \
   %D%/bootloader/depthcharge.scm                \
   %D%/ci.scm					\
+  %D%/home-services.scm                         \
   %D%/image.scm					\
   %D%/packages.scm				\
   %D%/packages/abduco.scm			\