;;; 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 shepherd)
  #:use-module (gnu home services)
  #:use-module (gnu packages admin)
  #:use-module (gnu services shepherd)
  #:use-module (guix sets)
  #:use-module (guix gexp)
  #:use-module (guix records)

  #:use-module (srfi srfi-1)

  #:export (home-shepherd-service-type
            home-shepherd-configuration)
  #:re-export (shepherd-service
               shepherd-action))

(define-record-type* <home-shepherd-configuration>
  home-shepherd-configuration make-home-shepherd-configuration
  home-shepherd-configuration?
  (shepherd home-shepherd-configuration-shepherd
            (default shepherd)) ; package
  (auto-start? home-shepherd-configuration-auto-start?
               (default #t))
  (services home-shepherd-configuration-services
            (default '())))

(define (home-shepherd-configuration-file services shepherd)
  "Return the shepherd configuration file for SERVICES.  SHEPHERD is used
as shepherd package."
  (assert-valid-graph services)

  (let ((files (map shepherd-service-file services))
        ;; TODO: Add compilation of services, it can improve start
        ;; time.
        ;; (scm->go (cute scm->go <> shepherd))
        )
    (define config
      #~(begin
          (use-modules (srfi srfi-34)
                       (system repl error-handling))
          (apply
           register-services
           (map
            (lambda (file) (load file))
            '#$files))
          (action 'root 'daemonize)
          (format #t "Starting services...~%")
          (for-each
           (lambda (service) (start service))
           '#$(append-map shepherd-service-provision
                          (filter shepherd-service-auto-start?
                                  services)))
          (newline)))

    (scheme-file "shepherd.conf" config)))

(define (launch-shepherd-gexp config)
  (let* ((shepherd (home-shepherd-configuration-shepherd config))
         (services (home-shepherd-configuration-services config)))
    (if (home-shepherd-configuration-auto-start? config)
        (with-imported-modules '((guix build utils))
          #~(let ((log-dir (or (getenv "XDG_LOG_HOME")
                               (format #f "~a/.local/var/log" (getenv "HOME")))))
              ((@ (guix build utils) mkdir-p) log-dir)
              (system*
               #$(file-append shepherd "/bin/shepherd")
               "--logfile"
               (string-append
                log-dir
                "/shepherd.log")
               "--config"
               #$(home-shepherd-configuration-file services shepherd))))
        #~"")))

(define (reload-configuration-gexp config)
  (let* ((shepherd (home-shepherd-configuration-shepherd config))
         (services (home-shepherd-configuration-services config)))
    #~(system*
       #$(file-append shepherd "/bin/herd")
       "load" "root"
       #$(home-shepherd-configuration-file services shepherd))))

(define (ensure-shepherd-gexp config)
  #~(if (file-exists?
         (string-append
          (or (getenv "XDG_RUNTIME_DIR")
              (format #f "/run/user/~a" (getuid)))
          "/shepherd/socket"))
        #$(reload-configuration-gexp config)
        #$(launch-shepherd-gexp config)))

(define-public home-shepherd-service-type
  (service-type (name 'home-shepherd)
                (extensions
                 (list (service-extension
                        home-run-on-first-login-service-type
                        launch-shepherd-gexp)
                       (service-extension
                        home-activation-service-type
                        ensure-shepherd-gexp)
                       (service-extension
                        home-profile-service-type
                        (lambda (config)
                          `(,(home-shepherd-configuration-shepherd config))))))
                (compose concatenate)
                (extend
                 (lambda (config extra-services)
                   (home-shepherd-configuration
                    (inherit config)
                    (services
                     (append (home-shepherd-configuration-services config)
                             extra-services)))))
                (default-value (home-shepherd-configuration))
                (description "Configure and install userland Shepherd.")))

(define-service-type-mapping
  shepherd-root-service-type => home-shepherd-service-type)