hyprpaper: add module

modules/services/hyprpaper.nix

@@ -0,0 +1,89 @@
+{ config, lib, pkgs, ... }:
+with lib;
+let
+
+  cfg = config.services.hyprpaper;
+in {
+  meta.maintainers = [ maintainers.khaneliman maintainers.fufexan ];
+
+  options.services.hyprpaper = {
+    enable = mkEnableOption "Hyprpaper, Hyprland's wallpaper daemon";
+
+    package = mkPackageOption pkgs "hyprpaper" { };
+
+    settings = lib.mkOption {
+      type = with lib.types;
+        let
+          valueType = nullOr (oneOf [
+            bool
+            int
+            float
+            str
+            path
+            (attrsOf valueType)
+            (listOf valueType)
+          ]) // {
+            description = "Hyprpaper configuration value";
+          };
+        in valueType;
+      default = { };
+      description = ''
+        hyprpaper configuration written in Nix. Entries with the same key
+        should be written as lists. Variables' and colors' names should be
+        quoted. See <https://wiki.hyprland.org/Hypr-Ecosystem/hyprpaper/> for more examples.
+      '';
+      example = lib.literalExpression ''
+        {
+          ipc = "on";
+          splash = false;
+          splash_offset = 2.0;
+
+          preload =
+            [ "/share/wallpapers/buttons.png" "/share/wallpapers/cat_pacman.png" ];
+
+          wallpaper = [
+            "DP-3,/share/wallpapers/buttons.png"
+            "DP-1,/share/wallpapers/cat_pacman.png"
+          ];
+        }
+      '';
+    };
+
+    importantPrefixes = lib.mkOption {
+      type = with lib.types; listOf str;
+      default = [ "$" ];
+      example = [ "$" ];
+      description = ''
+        List of prefix of attributes to source at the top of the config.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    xdg.configFile."hypr/hyprpaper.conf" = mkIf (cfg.settings != { }) {
+      text = lib.hm.generators.toHyprconf {
+        attrs = cfg.settings;
+        inherit (cfg) importantPrefixes;
+      };
+    };
+
+    systemd.user.services.hyprpaper = {
+      Install = { WantedBy = [ "graphical-session.target" ]; };
+
+      Unit = {
+        ConditionEnvironment = "WAYLAND_DISPLAY";
+        Description = "hyprpaper";
+        After = [ "graphical-session-pre.target" ];
+        PartOf = [ "graphical-session.target" ];
+        X-Restart-Triggers =
+          [ "${config.xdg.configFile."hypr/hyprpaper.conf".source}" ];
+      };
+
+      Service = {
+        ExecStart = "${getExe cfg.package}";
+        Restart = "always";
+        RestartSec = "10";
+      };
+    };
+  };
+}