From 937fc746ea4c5d3e7d20f40b0c6ee74daabd14b5 Mon Sep 17 00:00:00 2001
From: Timo Wilken
Date: Tue, 9 May 2023 20:20:50 -0400
Subject: Add script to set timezone from the network

---
 tw/system/lap.scm | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

(limited to 'tw/system/lap.scm')

diff --git a/tw/system/lap.scm b/tw/system/lap.scm
index 9a1b8571..307cf590 100644
--- a/tw/system/lap.scm
+++ b/tw/system/lap.scm
@@ -21,7 +21,7 @@
   #:use-module (tw system))
 
 (use-package-modules android certs cups disk docker file-systems gnome
-                     kerberos linux mtools pulseaudio search shells wm xorg)
+                     kerberos linux mtools pulseaudio search shells tls wm xorg)
 
 (use-service-modules admin authentication avahi base cups dbus desktop docker
                      kerberos linux mcron networking pm syncthing vpn xorg)
@@ -100,6 +100,29 @@ EndSection
  )
 "))
 
+(define set-timezone-script
+  ;; Every time we connect to a network, get our timezone from network geolocation.
+  ;; https://wiki.archlinux.org/title/System_time
+  (with-extensions (list guile-gnutls)  ; needed by (web client)
+    #~(begin
+        (use-modules (srfi srfi-11)  ; `let-values'
+                     (web client)
+                     (web response))
+        (define tz-api-url "https://ipapi.co/timezone")
+        (define /etc/localtime "/etc/localtime")
+        ;; According to the Arch Wiki, when checking for "up" as the second
+        ;; argument, VPN connections could cause undesired timezone changes.
+        (when (and (string=? "connectivity-change" (caddr (command-line)))
+                   (string=? "FULL" (getenv "CONNECTIVITY_STATE")))
+          (let-values (((response timezone) (http-get tz-api-url)))
+            (unless (= 200 (response-code response))
+              (error "Got error response to request:" response))
+            (let ((zonefile (string-append #$tzdata "/share/zoneinfo/" timezone)))
+              (delete-file /etc/localtime)
+              (symlink zonefile /etc/localtime)
+              (format (current-error-port)
+                      "Successfully updated timezone to ~a" timezone)))))))
+
 ;; TODO: Nouveau claims (in dmesg) that I have a NVIDIA GM204.  Maybe
 ;; only use (select-firmware "^nvidia/gm204/").  linux-firmware only
 ;; has a gr/ subdir for that, and acr/ symlinked from gm200.  No pmu/
@@ -380,6 +403,9 @@ support extra features (acr, pmu, gr).")
       (extra-special-file "/etc/guix/channels.scm"
                           (scheme-file "channels.scm" system-channels))
 
+      (extra-special-file "/etc/NetworkManager/dispatcher.d/09-set-timezone"
+                          (program-file "set-timezone" set-timezone-script))
+
       (modify-services %desktop-services
         (gdm-service-type
          config =>
-- 
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