(use-modules (guix monads)
             (guix store)
             (guix gexp)
             (guix packages)
             (guix utils)
             (gnu packages base))


(define* (%default-environ #:key locale timezone)
  "Return the default environment variables as a alist."
  (mlet %store-monad ((tzdir (package-file tzdata "share/zoneinfo")))
    (let ((path '("/run/setuid-programs"
                  "$HOME/.guix-profile/bin"
                  "$HOME/.guix-profile/sbin"
                  "/run/current-system/profile/bin"
                  "/run/current-system/profile/sbin"))
          (infopath '("$HOME/.guix-profile/share/info"
                      "/run/current-system/profile/share/info"))
          ;; Tell 'modprobe' & co. where to look for modules.
          (linux-module-directory
           "/run/booted-system/kernel/lib/modules"))
      (return `(("LANG" . ,locale)
                ("TZ" . ,timezone)
                ("TZDIR" . ,tzdir)
                ("LINUX_MODULE_DIRECTORY" . ,linux-module-directory)
                ("PATH" . ,path)
                ("INFOPATH" . ,infopath))))))

(define (%default-/etc/profile menv)
  "Return the default /etc/profile."
  (mlet %store-monad ((env menv))
    (define (sh-setenv name value)
      (format #f "export ~a=~a\n"
              name
              (if (list? value)
                  (string-join value ":")
                  value)))
    (text-file "profile"
               (apply string-append
                      (map (lambda (e)
                             (sh-setenv (car e) (cdr e)))
                           env)))))

(define (%default-/etc/zlogin)
  "Return the default /etc/zlogin."
  (text-file "zlogin" "source /etc/profile/n"))

(define (%default-/etc/fish/config.fish menv)
  "Return the default /etc/fish/config.fish."
  (mlet %store-monad ((env menv))
    (define (fish-setenv name value)
      (format #f "    set -gx ~a ~a\n"
              name
              (if (list? value)
                  (string-join value " ")
                  value)))
    (text-file "config.fish" (string-append
                              "if status --is-login\n"
                              (apply string-append
                                     (map (lambda (e)
                                            (fish-setenv (car e) (cdr e)))
                                          env))
                              "end\n"))))

(display (run-with-store (open-connection)
           (%default-/etc/fish/config.fish
            (%default-environ #:locale "en_US.utf8"
                              #:timezone "Asia/Shanghai"))))