;; This is an operating system configuration file for a fairly minimal
;; "desktop" setup with i3 where the /home partition partition is
;; encrypted with LUKS.
;;
;; https://guix.gnu.org/manual/en/html_node/operating_002dsystem-Reference.html

(define-module (tw system lap)
  #:use-module (gnu)
  #:use-module (gnu bootloader grub)
  #:use-module (gnu system locale)
  #:use-module (gnu system nss)
  #:use-module (guix gexp)
  #:use-module (guix packages)
  #:use-module ((guix utils) #:select (substitute-keyword-arguments))
  #:use-module ((nongnu packages linux)
                #:prefix nongnu:)   ; don't interfere with (gnu packages linux)
  #:use-module (nongnu packages nvidia)
  #:use-module (nongnu packages scanner)
  #:use-module (nongnu services nvidia)
  #:use-module (nongnu system linux-initrd)
  #:use-module (nonguix licenses)
  #:use-module (tw channels)
  #:use-module (tw packages scanner)
  #:use-module (tw services secrets)
  #:use-module (tw services wireguard)
  #:use-module (tw system))

(use-package-modules android certs cups disk docker file-systems gnome guile
                     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 shepherd syncthing vpn xorg)

(define efi-system-partition          ; /dev/nvme0n1p1
  (uuid "E04A-DF05" 'fat))
(define tilearch-root-partition       ; /dev/nvme0n1p2
  (uuid "197c7f98-c780-4017-9bf7-212175967fd0" 'btrfs))
(define guixsd-root-partition         ; /dev/nvme0n1p3
  (uuid "2169a07b-b7b6-4e3d-8e59-bf00d0baffc4" 'btrfs))
(define swap-partition                ; /dev/nvme0n1p4
  (uuid "2c78d507-5cd1-48da-ba8d-d1b01d6ff8f9"))
(define data-partition-outside-luks   ; /dev/sda1
  (uuid "43108ff6-b25a-4a53-b3f7-6d03ff3e0022"))
(define data-partition-inside-luks    ; /dev/mapper/data
  (uuid "826bb1a7-1069-46a5-897a-afa19272fbb0" 'btrfs))

(define backlight-udev-rules
  ;; The naive approach of GROUP="video", MODE="0664" doesn't seem to work.
  ;; https://github.com/haikarainen/light/blob/master/90-backlight.rules
  ;; https://github.com/Hummer12007/brightnessctl/blob/master/90-brightnessctl.rules
  (udev-rule "90-backlight.rules" "\
ACTION!=\"remove\", SUBSYSTEM==\"backlight\", GROUP=\"video\", MODE=\"0664\"
ACTION!=\"remove\", SUBSYSTEM==\"leds\", GROUP=\"video\", MODE=\"0664\"
"))

;; This text is added verbatim to the Xorg config file.
(define touchpad-xorg-config "\
# see man 4 libinput
Section \"InputClass\"
    Identifier \"touchpad\"
    Driver \"libinput\"
    MatchIsTouchpad \"true\"

    Option \"DisableWhileTyping\" \"true\"
    Option \"MiddleEmulation\" \"true\"
    Option \"NaturalScrolling\" \"true\"
    Option \"HorizontalScrolling\" \"true\"
    Option \"ScrollMethod\" \"twofinger\"
    Option \"ClickMethod\" \"clickfinger\"
    Option \"Tapping\" \"true\"
    Option \"TappingDrag\" \"true\"
    Option \"TappingDragLock\" \"false\"
    Option \"TappingButtonMap\" \"lrm\"
EndSection
")

(define custom-xorg-config
  (xorg-configuration
   (keyboard-layout %british-keyboard)
   (extra-config (list touchpad-xorg-config))
   ;; TODO: run acpid so nvidia driver can connect?
   ;; See `guix show nvidia-driver'
   (modules (cons* nvidia-driver %default-xorg-modules))
   (drivers '("nvidia" "modesetting"))))

(define set-timezone-script
  ;; Every time we connect to a network, get our timezone from network geolocation.
  ;; https://wiki.archlinux.org/title/System_time
  ;; https://wiki.archlinux.org/title/Network_configuration/Wireless#Respecting_the_regulatory_domain
  (with-extensions (list guile-json-4 guile-gnutls)  ; guile-gnutls needed by (web client)
    #~(begin
        (use-modules ((srfi srfi-11) #:select (let-values))
                     (json)
                     (web client)
                     (web response))
        (define api-url "https://ipapi.co/json")
        ;; 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 text) (http-get api-url)))
            (unless (= 200 (response-code response))
              (error "Got error response to request:" response))
            (let* ((json (json-string->scm text))
                   (timezone (assoc-ref json "timezone"))
                   (zonefile (string-append #$tzdata "/share/zoneinfo/" timezone))
                   (regdb-country (assoc-ref json "country_code"))
                   (error-code
                    (status:exit-val
                     ;; Set WiFi regulatory domain to use the correct channels.
                     (system* #$(file-append iw "/bin/iw") "reg" "set" regdb-country))))
              (format (current-error-port) "Updated WiFi regdomain to ~a: ~a~%"
                      regdb-country (if (zero? error-code) "success"
                                        (format #f "error ~d" error-code)))
              ;; Set local timezone.
              (delete-file "/etc/localtime")
              (symlink zonefile "/etc/localtime")
              (format (current-error-port)
                      "Updated timezone to ~a: success~%" timezone)))))))

(define-public %lap-system
  (operating-system
    (host-name "lap.twilken.net")
    (timezone "Europe/Paris")
    (locale "en_GB.utf8")
    (locale-definitions
     (list (locale-definition (name "en_GB.utf8") (source "en_GB"))
           (locale-definition (name "en_US.utf8") (source "en_US"))
           (locale-definition (name "fr_FR.utf8") (source "fr_FR"))))

    ;; Allow resolution of '.local' host names with mDNS.
    (name-service-switch %mdns-host-lookup-nss)

    ;; Choose UK English X11 keyboard layout.
    (keyboard-layout %british-keyboard)

    ;; Use the UEFI variant of GRUB with the EFI System
    ;; Partition mounted on /boot/efi.
    (bootloader
     (bootloader-configuration
      (bootloader grub-efi-bootloader)
      (targets '("/boot/efi"))
      ;; Note: keyboard-layout is ignored by non-grub bootloaders.
      (keyboard-layout keyboard-layout)
      (menu-entries
       (list
        (menu-entry
         (label "systemd-boot")
         (device efi-system-partition)
         (chain-loader "/EFI/systemd/systemd-bootx64.efi"))))))

    ;; Use non-free kernel to load non-free firmware (e.g. for wifi).
    (kernel nongnu:linux-lts)
    (kernel-arguments
     (cons* ;;"nosplash"
      ;;"vt.global_cursor_default=0"
      ;;"video.use_native_backlight=1"
      ;; Needed for PRIME synchronization:
      ;; https://wiki.archlinux.org/title/PRIME#PRIME_synchronization
      ;; https://wiki.archlinux.org/title/NVIDIA#DRM_kernel_mode_setting
      "nvidia-drm.modeset=1"
      ;;"acpi_osi=\"!Windows 2015\""
      ;;"acpi_enforce_resources=lax"
      "modprobe.blacklist=nouveau"  ; prevent interference with nvidia
      %default-kernel-arguments))
    (initrd microcode-initrd)
    (firmware (cons* nongnu:atheros-firmware   ; for atk10k/QCA6174/hw3.0 (wifi card)
                     nongnu:i915-firmware      ; for Intel GPU runtime power management etc
                     %base-firmware))

    ;; Specify a mapped device for the encrypted home partition.
    ;; The UUID is that returned by 'cryptsetup luksUUID'.
    (mapped-devices
     (list (mapped-device
            (source data-partition-outside-luks)
            (target "data")
            (type luks-device-mapping))))

    (swap-devices
     (list (swap-space
            (target swap-partition)
            (discard? #t))))

    (file-systems
     (cons* (file-system
              (device guixsd-root-partition)
              (mount-point "/")
              (flags '(no-atime))
              (options (alist->file-system-options
                        '("ssd" ("compress" . "zstd"))))
              (type "btrfs"))
            (file-system
              (device efi-system-partition)
              (mount-point "/boot/efi")
              (flags '(no-atime))
              (type "vfat"))
            (file-system
              (device data-partition-inside-luks)
              (mount-point "/home")
              (flags '(no-atime))
              (options (alist->file-system-options
                        '("ssd" ("compress" . "zstd")
                          ("subvol" . "home/guixsd"))))
              (type "btrfs")
              (dependencies mapped-devices))
            %base-file-systems))

    ;; Members of the wheel group are allowed to use sudo.
    (users (cons* (user-account
                   (name "timo")
                   (comment "Timo Wilken")
                   (group "users")
                   (supplementary-groups
                    '("wheel" "audio" "video" "docker" "adbusers"))
                   (shell (file-append zsh "/bin/zsh")))
                  %base-user-accounts))

    (sudoers-file
     (plain-file "sudoers"
       (string-append
        ;; We need to preserve $TERMINFO so that programs under sudo can
        ;; find kitty's terminfo files. This is possibly unsafe; sudo
        ;; explicitly deletes this variable by default.
        "Defaults env_keep += \"TERMINFO\"\n"
        (plain-file-content %sudoers-specification)
        ;; In addition to the default rules, allow admins to power off
        ;; the computer. They'll have to use the system binaries, not
        ;; those from their user profile, as /etc/sudoers requires
        ;; absolute paths to commands.
        "%wheel ALL=(ALL) NOPASSWD: "
        "/run/current-system/profile/sbin/halt, "
        "/run/current-system/profile/sbin/reboot, "
        "/run/current-system/profile/sbin/shutdown\n")))

    ;; This is where we specify system-wide packages.
    (packages
     (cons*
      ;; System stuff
      cups docker mit-krb5
      ;; File systems
      dosfstools mtools ntfs-3g
      ;; Desktop and drivers
      ;; FIXME: lightdm depends on python-2, but the build throws an
      ;; error that python2 is not supported.
      ;; TODO: Does lightdm have a service I need to enable?
      ;;lightdm lightdm-gtk-greeter
      pulseaudio xf86-video-intel xf86-video-nouveau
      ;; Adds /sys/class/backlight entries for external monitors.
      ;; Not needed for laptop display.
      ;; ddcci-driver-linux
      i3-gaps  ; install i3 here so gdm can see its xsession file
      i3lock   ; we need a system service to make i3lock setuid root
      ;; We need to install gnome-keyring here so its PAM module is
      ;; enabled properly (by its service; see below).
      ;; nheko needs gnome-keyring to store secrets (kwallet doesn't do dbus).
      gnome-keyring
      ;; It's probably easiest to install geoclue system-wide, so it
      ;; gets added to `%desktop-services' and redshift can access the
      ;; location.
      geoclue
      ;; Proprietary NVIDIA driver. See its description for more required setup steps.
      nvidia-driver
      ;; Base packages
      %base-system-packages))

    ;; Use the "desktop" services, which include the X11
    ;; log-in service, networking with NetworkManager, and more.
    ;; See info '(guix)Services' for useful services.
    (services
     (cons*
      (service syncthing-service-type
        (syncthing-configuration
         (user "timo")))

      (service cups-service-type
        (cups-configuration
         (web-interface? #t)
         (default-shared? #f)
         ;; See info '(guix)Printing Services' for more extensions.
         (extensions
          (list cups-filters foomatic-filters brlaser))))

      (service bluetooth-service-type)

      (service tw-wireguard-service-type
        (tw-wireguard-configuration
         (this-host host-name)))

      (service docker-service-type
        (docker-configuration))

      (service krb5-service-type
        (krb5-configuration
         (default-realm "CERN.CH")
         (rdns? #f)
         (realms (list (krb5-realm
                        (name "CERN.CH")
                        (default-domain "cern.ch")
                        (kdc "cerndc.cern.ch"))))))

      (service tlp-service-type
        (tlp-configuration))   ; TODO: configure properly

      (service thermald-service-type
        (thermald-configuration
         (adaptive? #t)))

      (service earlyoom-service-type
        (earlyoom-configuration))  ; TODO: configure at least `avoid-regexp'

      ;; Disabled as it doesn't work with my hardware.
      ;; It always says "logging in with fingerprint failed" and blocks password login in gdm.
      ;; (service fprintd-service-type)

      ;; Install i3lock as a setuid binary, so it can talk to PAM.
      (service screen-locker-service-type
        (screen-locker-configuration
         (name "i3lock")
         (program (file-append i3lock "/bin/i3lock"))))

      ;; gnome-keyring is not in `%desktop-services' by default,
      ;; but needs to be there to add itself to /etc/pam.d/.
      ;; If using a DM other than GDM, add it to `pam-services' in
      ;; `gnome-keyring-configuration' (see its docs).
      (service gnome-keyring-service-type
        (gnome-keyring-configuration))

      ;; Allow anyone in the "video" group to set the display's brightness.
      ;; Run `udevadm info -q all /sys/class/backlight/intel_backlight'
      ;; to see properties.
      (udev-rules-service 'backlight backlight-udev-rules #:groups '("video"))
      ;; According to "info '(guix) Base Services'", the above should
      ;; have a `#:groups '("video")', but that group is already
      ;; declared as a supplementary group for my user and guix warns
      ;; that it's declared twice.

      (udev-rules-service 'android android-udev-rules #:groups '("adbusers"))

      (set-xorg-configuration custom-xorg-config)

      (service nvidia-service-type)  ; proprietary nvidia driver

      ;; For some reason, none of the NVIDIA things create this device file
      ;; automatically, even though the NVIDIA Xorg driver requires it (Xorg
      ;; fails to start otherwise).
      (simple-service 'create-nvidiactl shepherd-root-service-type
        (list
         (shepherd-service
          (documentation "Create /dev/nvidiactl.")
          (provision '(nvidiactl))
          (requirement '(nvidia))
          (one-shot? #t)
          (start #~(make-forkexec-constructor
                    (list #$(file-append coreutils "/bin/mknod")
                          "-m" "666" "/dev/nvidiactl" "c" "195" "255")))
          (stop #~(make-forkexec-constructor
                   (list #$(file-append coreutils "/bin/rm")
                         "-f" "/dev/nvidiactl"))))))

      (service unattended-upgrade-service-type
        (unattended-upgrade-configuration
         (schedule "0 21 * * *")       ; every night at 21:00, when the laptop is turned on
         (maximum-duration (* 40 60))  ; 40 minutes to allow for slow downloads
         (channels %system-channels)
         (operating-system-expression
          #~(@ (tw system lap) %lap-system))
         (services-to-restart
          ;; Anything that won't cause disruption when restarting.
          '(syncthing-timo earlyoom thermald tlp wireguard-wg0 mcron))))

      (simple-service 'disk-maintenance mcron-service-type
        ;; I don't think jobs run on boot if they would have run when the
        ;; computer was turned off, so choose a time when the computer is
        ;; probably turned on.
        (list #~(job "45 21 * * *" "guix gc -d 2w -F 25G")  ; after unattended-upgrade
              #~(job "0 22 * * *"  ; after guix gc
                     (string-append #$(file-append util-linux "/sbin/fstrim")
                                    " --fstab --verbose"))))

      (extra-special-file "/etc/NetworkManager/dispatcher.d/09-set-timezone"
        (program-file "set-timezone" set-timezone-script))

      (simple-service 'xbacklight-services shepherd-root-service-type
        (list
         (shepherd-service
          (documentation "Set laptop screen backlight on boot.")
          (provision '(backlight))
          (one-shot? #t)
          (start #~(make-forkexec-constructor
                    (list #$(program-file "backlight-setter"
                              #~(begin
                                  (use-modules ((ice-9 textual-ports) #:select (get-string-all))
                                               ((srfi srfi-26) #:select (cut)))
                                  (define brightness-file "/sys/class/backlight/intel_backlight/brightness")
                                  (define max-brightness-file "/sys/class/backlight/intel_backlight/max_brightness")
                                  ;; These files don't exist right after startup, so wait for them to appear.
                                  (while (not (and (file-exists? max-brightness-file)
                                                   (file-exists? brightness-file)))
                                    (format (current-error-port) "Waiting for /sys files to appear...~%")
                                    (sleep 1))
                                  (define max-brightness
                                    (call-with-input-file max-brightness-file get-string-all))
                                  (call-with-output-file brightness-file
                                    (cut display max-brightness <>))))))))))

      (simple-service 'scanning-services shepherd-root-service-type
        (list
         (shepherd-service
          (documentation "Expose USB scanners over IPP.")
          (provision '(ipp-usb))
          (requirement '(networking))   ; only on localhost, though
          (start #~(make-forkexec-constructor
                    (list #$(file-append ipp-usb "/bin/ipp-usb") "standalone")))
          (stop #~(make-kill-destructor)))))

      ;; Since Guix 953c65ffdd4, build-machines can be directly specified in
      ;; `guix-configuration'. However, this doesn't allow the dynamic
      ;; selection of build machines as is done here.
      (extra-special-file "/etc/guix/machines.scm"
        (scheme-file "machines.scm"
          #~(let ((lud (build-machine
                        (name "lud.twilken.net")
                        (systems '("x86_64-linux"))
                        (port '#$(assoc-ref %ssh-ports "lud.twilken.net"))
                        (host-key "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIGqXbxv3a2bZyGjnEirVCMtRBeLKW/ha8ULSR9Xye4Z1")
                        (user "timo")
                        (private-key "/home/timo/.local/share/ssh-keys/id_rsa")
                        (speed .5)))   ; 4 cores, 16 GB RAM
                  (vin (build-machine
                        (name "vin.twilken.net")
                        (systems '("x86_64-linux"))
                        (port '#$(assoc-ref %ssh-ports "vin.twilken.net"))
                        (host-key "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEEpdfKxzoCwg53TKPF5YxgUwhGF+bELAyBGdxagQroJ")
                        (user "timo")
                        (private-key "/home/timo/.local/share/ssh-keys/id_rsa")
                        (speed 1.))))  ; 8 cores, 16 GB RAM
              (use-modules (ice-9 popen)
                           (ice-9 textual-ports)
                           (ice-9 regex))
              (let* ((regexp (make-regexp "^GENERAL\\.CONNECTION:[[:space:]]+TLAN$" regexp/newline))
                     (pipe (open-pipe* OPEN_READ #$(file-append network-manager "/bin/nmcli")
                                       "device" "show" "wlp3s0"))
                     (at-home? (regexp-exec regexp (get-string-all pipe))))
                (close-pipe pipe)
                ;; Only offload to vin when at home, as the network connection is too bad otherwise.
                (if at-home?
                    (list vin)
                    (list lud))))))

      (service secrets-service-type
        (secrets-configuration
         (secrets
          (list
           (secret
            (encrypted-file (local-file "files/wireguard/lap.key.enc"))
            (destination "/etc/wireguard/private.key"))
           (secret
            (encrypted-file (local-file "files/wireguard/lap-fp4.psk.enc"))
            (destination "/etc/wireguard/fp4.psk"))
           (secret
            (encrypted-file (local-file "files/wireguard/lap-lud.psk.enc"))
            (destination "/etc/wireguard/lud.psk"))
           (secret
            (encrypted-file (local-file "files/wireguard/lap-pi3.psk.enc"))
            (destination "/etc/wireguard/pi3.psk"))
           (secret
            (encrypted-file (local-file "files/wireguard/lap-vin.psk.enc"))
            (destination "/etc/wireguard/vin.psk"))))))

      (modify-services (append %system-channel-services %desktop-services)
        ;; Let sane find the airscan backend. ipp-usb needs to be running separately.
        (sane-service-type _ => sane-backends/airscan)

        (gdm-service-type
         config =>
         (gdm-configuration
          (inherit config)
          (auto-login? #f)
          (default-user "timo")
          (xorg-configuration custom-xorg-config)))

        (geoclue-service-type
         config =>
         (geoclue-configuration
          (inherit config)
          (applications
           (cons* (geoclue-application "redshift" #:system? #f)
                  %standard-geoclue-applications))))

        (login-service-type
         config =>
         (login-configuration
          (inherit config)
          (motd (plain-file "no-motd" ""))
          (allow-empty-passwords? #f))))))))

%lap-system