workflows/mosey-branch: create desktop session files package

This should make it easier to manage the custom desktop files with the
usual toolchain for configuring and installing custom desktop files
(i.e., Meson). While this could be done with Nix, some parts of
installing files is easier with Meson.

Who knows, it might be reverted because my Nix-fu is pretty weak right
now.

modules/nixos/workflows/mosey-branch/config/desktop-session/README.adoc

@@ -0,0 +1,4 @@
+= Mosey branch custom session
+:toc:
+
+This is an installation script for the custom desktop environment "Mosey branch".

modules/nixos/workflows/mosey-branch/config/desktop-session/default.nix

@@ -0,0 +1,36 @@
+{ stdenv
+, lib
+, meson
+, ninja
+, pkg-config
+
+# This is the prefix used for the installed files in the output.
+, prefix ? "one.foodogsquared.MoseyBranch"
+, serviceScript ? "Hyprland"
+, sessionScript ? "gnome-session --session=mosey-branch"
+}:
+
+stdenv.mkDerivation rec {
+  pname = "mosey-branch-custom-desktop-session";
+  version = "2023-08-11";
+
+  src = ./.;
+  nativeBulidInputs = [
+    meson
+    ninja
+    pkg-config
+  ];
+
+  mesonFlags = [
+    "-Dsession_script=${sessionScript}"
+    "-Dservice_script=${serviceScript}"
+  ];
+
+  passthru.providedSessions = [ "mosey-branch" ];
+
+  meta = with lib; {
+    description = "Custom desktop files for the custom desktop environment";
+    license = licenses.gpl3Plus;
+    platforms = platforms.linux;
+  };
+}

modules/nixos/workflows/mosey-branch/config/desktop-session/meson.build

@@ -0,0 +1,73 @@
+project('mosey-branch',
+  version: '2023-08-11',
+  license: 'GPL-3.0-or-later',
+  meson_version: '>=0.54.0',
+)
+
+app_id = 'one.foodogsquared.MoseyBranch'
+prefix = get_option('prefix')
+datadir = join_paths(prefix, get_option('datadir'))
+systemddir = join_paths(prefix, 'share/systemd')
+systemduserdir = join_paths(systemddir, 'user')
+
+required_components = [
+  #'polkit',
+  #'ibus',
+  #'ags',
+]
+
+session_dropins = [
+  'gnome-session@mosey-branch.target.d',
+]
+
+session_wants = ''
+foreach component : required_components
+  session_wants += 'Wants=' + app_id + '.' + component + '.target\n'
+endforeach
+
+# Install each gnome-session overrides.
+sessionconf = configuration_data()
+sessionconf.set('session_wants', session_wants)
+foreach session_dropin : session_dropins
+  configure_file(
+    input: 'mosey-branch.session.conf.in',
+    output: 'session.conf',
+    install_dir: join_paths(systemduserdir, session_dropin),
+    configuration: sessionconf,
+    install: true
+  )
+endforeach
+
+# Installing the Wayland session desktop entry.
+desktopentryconf = configuration_data()
+desktopentryconf.set('session_script', get_option('session_script'))
+configure_file(
+  input: 'mosey-branch.desktop',
+  install_dir: join_paths(datadir, 'wayland-sessions'),
+  configuration: desktopentryconf,
+  install: true,
+)
+
+# Installing the core systemd units for the desktop session.
+targetconf = configuration_data()
+targetconf.set('app_id', app_id)
+configure_file(
+  input: 'mosey-branch.target',
+  output: app_id + '.target',
+  install_dir: systemduserdir,
+  configuration: targetconf,
+  install: true,
+)
+
+serviceconf = configuration_data()
+serviceconf.set('script', get_option('service_script'))
+configure_file(
+  input: 'mosey-branch.service',
+  output: app_id + '.service',
+  install_dir: systemduserdir,
+  configuration: serviceconf,
+  install: true,
+)
+
+# TODO: Install the systemd units for the core components of the desktop
+# environment.

modules/nixos/workflows/mosey-branch/config/desktop-session/meson_options.txt

@@ -0,0 +1,11 @@
+option('service_script',
+  type: 'string',
+  value: 'Hyprland',
+  description: 'Executable for the main session script.'
+)
+
+option('session_script',
+  type: 'string',
+  value: 'gnome-session --session=mosey-branch',
+  description: 'Program (including its arguments) for the Wayland session entry file.',
+)

modules/nixos/workflows/mosey-branch/config/desktop-session/mosey-branch.desktop

@@ -1,7 +1,7 @@
 [Desktop Entry]
-Name=Hyprland
+Name=Mosey Branch
 Comment=foodogsquared's Hyprland-based desktop environment setup
-Exec=@script@
+Exec=@session_script@
-TryExec=@script@
+TryExec=@session_script@
 Type=Application
-DesktopNames=Hyprland
+DesktopNames=Mosey Branch

modules/nixos/workflows/mosey-branch/config/desktop-session/mosey-branch.service

@@ -0,0 +1,22 @@
+# This user service is intended to be started with gnome-session.
+[Unit]
+Description=Mosey Branch, a custom desktop session with Hyprland
+Documentation=https://wiki.hyprland.org
+
+After=gnome-manager-manager.target
+Requisite=gnome-session-initialized.target
+PartOf=gnome-session-initialized.target
+
+OnFailure=gnome-session-shutdown.target
+OnFailureJobMode=replace-irreversibly
+CollectMode=inactive-or-failed
+RefuseManualStart=true
+RefuseManualStop=true
+
+StartLimitBurst=4
+
+[Service]
+Type=notify
+Slice=session.slice
+Restart=on-failure
+ExecStart=@script@

modules/nixos/workflows/mosey-branch/config/desktop-session/mosey-branch.session.conf.in

@@ -0,0 +1,4 @@
+[Unit]
+@@
+
+Requires=one.foodogsquared.MoseyBranch.target

modules/nixos/workflows/mosey-branch/config/desktop-session/mosey-branch.target

@@ -0,0 +1,11 @@
+[Unit]
+Description=Mosey Branch
+Documentation=man:systemd.special(7)
+DefaultDependencies=no
+
+Requisite=gnome-session-initialized.target
+PartOf=gnome-session-initialized.target
+Before=gnome-session-initialized.target
+
+Requires=@app_id@.service
+After=@app_id@.service

modules/nixos/workflows/mosey-branch/config/gnome-session/hyprland.session

@@ -1,3 +0,0 @@
-[GNOME Session]
-Name=Hyprland
-RequiredComponents=@requiredComponents@

modules/nixos/workflows/mosey-branch/default.nix

@@ -4,35 +4,15 @@ let
   cfg = config.workflows.workflows.mosey-branch;
   workflowName = "mosey-branch";
 
-  # This is used in a similar manner for GNOME desktop applications and its
+  # A reverse DNS prefix similarly used to GNOME services.
-  # services.
+  prefix = "one.foodogsquared.MoseyBranch.";
-  prefix = "one.foodogsquared.${workflowName}.";
 
-  hyprlandCustomGnomeSession = pkgs.substituteAll {
+  customDesktopSession = pkgs.callPackage ./config/desktop-session {
-    src = ./config/gnome-session/hyprland.session;
+    inherit prefix;
-    name = "${workflowName}.session";
+    serviceScript = "${pkgs.hyprland}/bin/Hyprland --config ${./config/hyprland/hyprland.conf}";
-    dir = "share/gnome-session";
+    sessionScript = pkgs.writeShellScript "${workflowName}-hyprland-custom-start" ''
-    requiredComponents =
-      lib.concatMapString (component: "${prefix}${component};") ([
-        "ags"
-        "polkit"
-      ]
-      ++ lib.optional (config.i18n.inputMethod == "fcitx5") "fcitx5"
-      ++ lib.optional (config.i18n.inputMethod == "ibus") "ibus");
-  };
-
-  hyprlandStartScript = pkgs.writeShellScript "${workflowName}-hyprland-custom-start" ''
       ${pkgs.gnome.gnome-session}/bin/gnome-session --session=${workflowName}
     '';
-
-  hyprlandSessionPackage =
-    (pkgs.substituteAll {
-      src = ./config/wayland-sessions/hyprland.desktop;
-      name = "${workflowName}.desktop";
-      dir = "share/wayland-sessions";
-      script = hyprlandStartScript;
-    }).overrideAttrs {
-      passthru.providedSessions = [ workflowName ];
   };
 
   requiredPackages = with pkgs; [
@@ -46,8 +26,8 @@ let
     ags
     gtk4-layer-shell
 
-    # Install with the custom session.
+    # Install with the custom desktop session files.
-    hyprlandCustomGnomeSession
+    customDesktopSession
 
     # Optional dependencies that are required in this workflow module.
     socat
@@ -63,12 +43,6 @@ let
     # The chosen terminal emulator.
     wezterm
   ];
-
-  createPrefixedServices = name: value:
-    lib.nameValuePair "${prefix}${name}" (value // {
-      partOf = [ "graphical-session.target" ];
-      wantedBy = [ "gnome-session.target" ];
-    });
 in
 {
   options.workflows.workflows.mosey-branch = {
@@ -98,13 +72,14 @@ in
   config = lib.mkIf cfg.enable (lib.mkMerge [
     {
       environment.systemPackages = cfg.extraApps ++ requiredPackages;
+      systemd.packages = [ customDesktopSession ];
 
       # Our preferred display manager.
       services.xserver = {
         enable = true;
         displayManager = {
           gdm.enable = lib.mkDefault true;
-          sessionPackages = [ hyprlandSessionPackage ];
+          sessionPackages = [ customDesktopSession ];
         };
         updateDbusEnvironment = true;
       };
@@ -152,64 +127,6 @@ in
       };
     }
 
-    # These are all intended to be started with gnome-session.
-    # Much of the templates used are from Phosh systemd templates at
-    # https://gitlab.gnome.org/World/Phosh/phosh/-/blob/main/data/systemd.
-    # Big thanks to them! :)
-    {
-      systemd.user.targets."${prefix}" = {
-        description = "${workflowName} Hyprland shell";
-        documentation = [ "man:systemd.special(7)" ];
-        unitConfig.DefaultDependencies = "no";
-        requisite = [ "gnome-session-initialized.target" ];
-        partOf = [ "gnome-session-initialized.target" ];
-        before = [ "gnome-session-initialized.target" ];
-
-        wants = [ "${prefix}.service" ];
-        after = [ "${prefix}.service" ];
-      };
-
-      systemd.user.services = lib.mapAttrs' createPrefixedServices {
-        ags = {
-          description = "Widget system layer for the desktop";
-          script = "${pkgs.ags}/bin/ags";
-        };
-
-        polkit = {
-          description = "Authentication agent for the desktop session";
-          script = "${pkgs.polkit_gnome}/libexec/polkit-gnome-authentication-agent-1";
-        };
-
-        fcitx5 = lib.mkIf (config.i18n.inputMethod.enabled == "fcitx5") {
-          description = "Input method engine for the desktop session";
-          script = "${config.i18n.inputMethod.package}/bin/fcitx5";
-        };
-
-        ibus = lib.mkIf (config.i18n.inputMethod.enabled == "ibus") {
-          description = "Input method engine for the desktop session";
-          script = "${config.i18n.inputMethod.package}/bin/ibus start";
-        };
-      } // {
-        "${prefix}" = {
-          description = "${workflowName}, a custom desktop session with Hyprland";
-          documentation = [ "https://wiki.hyprland.org" ];
-          after = [ "gnome-manager-manager.target" ];
-          requisite = [ "gnome-session-initialized.target" ];
-          partOf = [ "gnome-session-initialized.target" ];
-
-          unitConfig = {
-            OnFailure = "gnome-session-shutdown.target";
-            OnFailureJobMode = "replace-irreversibly";
-            CollectMode = "inactive-or-failed";
-            RefuseManualStart = true;
-            RefuseManualStop = true;
-          };
-
-          script = "${pkgs.hyprland}/bin/Hyprland --config ${./config/hyprland/hyprland.conf}";
-        };
-      };
-    }
-
     # Setting up my project-specific profiles. This is only to be applied for
     # my setup. If you're not foodogsquared and you're using my project as one
     # of the flake input, this shouldn't be applied nor be used in the first