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

let
  cfg = config.programs.att_wm;
in
{
  options.programs.att_wm = {
    enable = lib.mkEnableOption "att_wm, a dwm-like window manager for river";

    package = lib.mkOption {
      type = lib.types.package;
      default = self.packages.${pkgs.stdenv.hostPlatform.system}.att_wm;
      defaultText = lib.literalMD "the flake's `att_wm` package";
      description = "The att_wm package to use.";
    };

    settings = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      example = lib.literalExpression "./config.zig";
      description = ''
        A replacement for att_wm's `src/config.zig`. att_wm is configured at
        compile time in the manner of dwm, so setting this rebuilds it.
      '';
    };

    autostart = lib.mkOption {
      type = lib.types.listOf lib.types.str;
      default = [ ];
      example = [ "quickshell" ];
      description = ''
        Commands appended to river's init script, run once the session starts.
        att_wm itself is always started last and kept in the foreground.
      '';
    };

    riverPackage = lib.mkOption {
      type = lib.types.package;
      default = pkgs.river;
      description = "The river package the init script is written for.";
    };
  };

  config = lib.mkIf cfg.enable (
    let
      att_wm =
        if cfg.settings == null then
          cfg.package
        else
          cfg.package.override { configFile = cfg.settings; };
    in
    {
      home.packages = [
        att_wm
        cfg.riverPackage
      ];

      # river runs this executable on startup and expects the window manager to
      # connect; keeping att_wm in the foreground ties the session's lifetime to
      # it, so quitting att_wm ends the session cleanly.
      xdg.configFile."river/init" = {
        executable = true;
        text = ''
          #!${pkgs.runtimeShell}
          ${lib.concatMapStringsSep "\n" (c: "${c} &") cfg.autostart}
          exec ${lib.getExe att_wm}
        '';
      };
    }
  );
}