emacs: add emacsclient desktop file

Add an option to enable a .desktop file for the Emacs client.

PR #1223

Co-authored-by: Michael Lingelbach <m.j.lbach@gmail.com>
Co-authored-by: Robert Helgesson <robert@rycee.net>

modules/services/emacs.nix

@@ -7,9 +7,40 @@ let
   cfg = config.services.emacs;
   emacsCfg = config.programs.emacs;
   emacsBinPath = "${emacsCfg.finalPackage}/bin";
+  # Adapted from upstream emacs.desktop
+  clientDesktopItem = pkgs.makeDesktopItem rec {
+    name = "emacsclient";
+    desktopName = "Emacs Client";
+    genericName = "Text Editor";
+    comment = "Edit text";
+    mimeType =
+      "text/english;text/plain;text/x-makefile;text/x-c++hdr;text/x-c++src;text/x-chdr;text/x-csrc;text/x-java;text/x-moc;text/x-pascal;text/x-tcl;text/x-tex;application/x-shellscript;text/x-c;text/x-c++;";
+    exec = "${emacsBinPath}/emacsclient ${
+        concatStringsSep " " cfg.client.arguments
+      } %F";
+    icon = "emacs";
+    type = "Application";
+    terminal = "false";
+    categories = "Utility;TextEditor;";
+    extraEntries = ''
+      StartupWMClass=Emacs
+    '';
+  };
 
 in {
-  options.services.emacs = { enable = mkEnableOption "the Emacs daemon"; };
+  options.services.emacs = {
+    enable = mkEnableOption "the Emacs daemon";
+    client = {
+      enable = mkEnableOption "generation of Emacs client desktop file";
+      arguments = mkOption {
+        type = with types; listOf str;
+        default = [ "-c" ];
+        description = ''
+          Command-line arguments to pass to <command>emacsclient</command>.
+        '';
+      };
+    };
+  };
 
   config = mkIf cfg.enable {
     assertions = [{
@@ -38,5 +69,7 @@ in {
 
       Install = { WantedBy = [ "default.target" ]; };
     };
+
+    home.packages = optional cfg.client.enable clientDesktopItem;
   };
 }