{ config, lib, pkgs, ... }:

with lib;

let

  cfg = config.services.dunst;
  toDunstIni = generators.toINI {
    mkKeyValue = key: value:
    let
      value' =
        if isBool value then (if value then "yes" else "no")
        else if isString value then "\"${value}\""
        else toString value;
    in
      "${key}=${value'}";
  };

  themeType = types.submodule {
    options = {
      package = mkOption {
        type = types.package;
        example = literalExample "pkgs.gnome3.adwaita-icon-theme";
        description = "Package providing the theme.";
      };

      name = mkOption {
        type = types.str;
        example = "Adwaita";
        description = "The name of the theme within the package.";
      };

      size = mkOption {
        type = types.str;
        default = "32x32";
        example = "16x16";
        description = "The desired icon size.";
      };
    };
  };

  hicolorTheme = {
    package = pkgs.hicolor_icon_theme;
    name = "hicolor";
    size = "32x32";
  };

in

{
  meta.maintainers = [ maintainers.rycee ];

  options = {
    services.dunst = {
      enable = mkEnableOption "the dunst notification daemon";

      iconTheme = mkOption {
        type = themeType;
        default = hicolorTheme;
        description = "Set the icon theme.";
      };

      settings = mkOption {
        type = types.attrsOf types.attrs;
        default = {};
        description = "Configuration written to ~/.config/dunstrc";
        example = literalExample ''
          {
            global = {
              geometry = "300x5-30+50";
              transparency = 10;
              frame_color = "#eceff1";
              font = "Droid Sans 9";
            };

            urgency_normal = {
              background = "#37474f";
              foreground = "#eceff1";
              timeout = 10;
            };
          };
        '';
      };
    };
  };

  config = mkIf cfg.enable (
    mkMerge [
      {
        home.file.".local/share/dbus-1/services/org.knopwob.dunst.service".source =
          "${pkgs.dunst}/share/dbus-1/services/org.knopwob.dunst.service";

        services.dunst.settings.global.icon_folders =
          let
            useCustomTheme =
              cfg.iconTheme.package != hicolorTheme.package
              || cfg.iconTheme.name != hicolorTheme.name
              || cfg.iconTheme.size != hicolorTheme.size;

            basePaths = [
              "/run/current-system/sw"
              "${config.home.homeDirectory}/.nix-profile"
              cfg.iconTheme.package
            ] ++ optional useCustomTheme hicolorTheme.package;

            themes =
              [
                cfg.iconTheme
              ] ++ optional useCustomTheme (
                hicolorTheme // { size = cfg.iconTheme.size; }
              );

            categories = [
              "actions"
              "animations"
              "apps"
              "categories"
              "devices"
              "emblems"
              "emotes"
              "filesystem"
              "intl"
              "mimetypes"
              "places"
              "status"
              "stock"
            ];
          in
            concatStringsSep ":" (
              concatMap (theme:
                concatMap (basePath:
                  map (category:
                    "${basePath}/share/icons/${theme.name}/${theme.size}/${category}"
                  ) categories
                ) basePaths
              ) themes
            );

        systemd.user.services.dunst = {
          Unit = {
            Description = "Dunst notification daemon";
            After = [ "graphical-session-pre.target" ];
            PartOf = [ "graphical-session.target" ];
          };

          Service = {
            Type = "dbus";
            BusName = "org.freedesktop.Notifications";
            ExecStart = "${pkgs.dunst}/bin/dunst";
          };
        };
      }

      (mkIf (cfg.settings != {}) {
        xdg.configFile."dunst/dunstrc".text = toDunstIni cfg.settings;
      })
    ]
  );
}