;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2023 Janneke Nieuwenhuizen <janneke@gnu.org>
;;;
;;; 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-xyz)
  #:use-module (ice-9 match)
  #:use-module (shepherd support)

  #:use-module (gnu home services)
  #:use-module (gnu home services shepherd)
  #:use-module (gnu packages ssh)
  #:use-module (gnu packages version-control)
  #:use-module (gnu services configuration)
  #:use-module (gnu services shepherd)
  #:use-module (guix records)
  #:use-module (guix gexp)

  #:export (home-git-daemon-configuration
            home-git-daemon-service-type
            home-ssh-agent-configuration
            home-ssh-agent-service-type))

;;; Commentary:
;;
;; Home Services for the Shepherd.
;;
;; Example configurations.
;;
;; Git daemon: use $HOME/src as the base directory.
;;
;; (service home-git-service-type
;;          (home-git-configuration
;;           (root (string-append (getenv "HOME") "/src"))))
;;
;; Ssh-agent
;;
;; Add to your ~/.bash_profile:
;;
;; SSH_AUTH_SOCK=${XDG_RUNTIME_DIR-$HOME/.cache}/ssh-agent/socket
;; export SSH_AUTH_SOCK
;;
;; (service home-ssh-agent-service-type)
;;
;;; Code:

;;;
;;; Directories.
;;;
(define %user-data-home
  ;; Default cache directory if shepherd is run as a normal user.
  (string-append (or (getenv "XDG_DATA_HOME")
                     (string-append user-homedir "/.local/share"))))

(define %user-log-dir
  ;; Default log directory if shepherd is run as a normal user.
  (string-append (or (getenv "XDG_DATA_HOME")
                     (string-append user-homedir "/.local/share"))
                 "/shepherd"))


;;;
;;; Git daemon.
;;;
(define-record-type* <home-git-daemon-configuration>
  home-git-daemon-configuration make-home-git-daemon-configuration
  home-git-daemon-configuration?
  (git home-git-daemon-git              ;string
       (default #~(string-append #$git "/bin/git")))
  (root home-git-daemon-root            ;string
    (default (string-append %user-data-home "/git-daemon")))
  (log-dir home-git-daemon-log-dir      ;string
           (default %user-log-dir)))

(define (home-git-daemon-services config)
  "Return a <shepherd-service> for a git daemon with CONFIG."
  (match config
    (($ <home-git-daemon-configuration> git root log-dir)
     (list (shepherd-service
            (documentation "Run the git daemon.")
            (provision '(git-daemon))
            (start #~(lambda _
                       (unless (file-exists? #$log-dir)
                         (mkdir-p #$log-dir))
                       (fork+exec-command
                        (list #$git
                              "daemon"
                              (string-append "--base-path=" #$root)
                              "--export-all")
                        #:log-file (string-append #$log-dir "/git-daemon.log"))))
            (stop #~(make-kill-destructor)))))))

(define home-git-daemon-service-type
  (service-type
   (name 'home-git-daemon)
   (default-value (home-git-daemon-configuration))
   (extensions
    (list (service-extension home-shepherd-service-type
                             home-git-daemon-services)))
   (description
    "Install and configure the git-daemon as a shepherd service.")))


;;;
;;; Ssh-agent.
;;;
(define-record-type* <home-ssh-agent-configuration>
  home-ssh-agent-configuration make-home-ssh-agent-configuration
  home-ssh-agent-configuration?
  (ssh-agent home-ssh-agent-ssh-agent   ;string
             (default #~(string-append #$openssh "/bin/ssh-agent")))
  (socket-dir home-ssh-agent-socket-dir ;string
              (default (string-append %user-runtime-dir "/ssh-agent")))
  (log-dir home-ssh-agent-log-dir       ;string
           (default %user-log-dir)))

(define (home-ssh-agent-services config)
  "Return a <shepherd-service> for an ssh-agent with CONFIG."
  (match config
    (($ <home-ssh-agent-configuration> ssh-agent socket-dir log-dir)
     (list (shepherd-service
            (documentation "Run the ssh-agent.")
            (provision '(ssh-agent))
            (start #~(lambda _
                       (unless (file-exists? #$socket-dir)
                         (mkdir-p #$socket-dir)
                         (chmod #$socket-dir #o700))
                       (unless (file-exists? #$log-dir)
                         (mkdir-p #$log-dir))
                       (fork+exec-command
                        (list #$ssh-agent
                              "-D"
                              "-a" (string-append #$socket-dir "/socket"))
                        #:log-file (string-append #$log-dir "/ssh-agent.log"))))
            (stop #~(make-kill-destructor)))))))

(define home-ssh-agent-service-type
  (service-type
   (name 'home-ssh-agent)
   (default-value (home-ssh-agent-configuration))
   (extensions
    (list (service-extension home-shepherd-service-type
                             home-ssh-agent-services)))
   (description
    "Install and configure the ssh-agent as a shepherd service.")))