{ config, lib, pkgs, ... }:
let
  cfg = config.programs.hyprscrolling;

  # Render plugin settings into:
  # plugin:hyprscrolling {
  #   key = value
  # }
  renderValue = v:
    if lib.isString v then "\"${v}\""
    else if lib.isBool v then (if v then "true" else "false")
    else if lib.isInt v || lib.isFloat v then toString v
    else if lib.isList v then
      "[ " + (lib.concatStringsSep " " (map renderValue v)) + " ]"
    else
      throw "programs.hyprscrolling.settings: unsupported value type: ${builtins.typeOf v}";

  renderSettings = settings:
    let
      lines = lib.mapAttrsToList (k: v: "  ${k} = ${renderValue v}") settings;
    in
      if settings == { } then ""
      else ''
        plugin:hyprscrolling {
        ${lib.concatStringsSep "\n" lines}
        }
      '';

  defaultPluginPkg = (pkgs.hyprlandPlugins.hyprscrolling or null);

  # Stable paths (avoid pinning /nix/store/... in your hyprland.conf)
  stableSoPath = "/etc/hypr/plugins/libhyprscrolling.so";
  dropInConfPath = "/etc/hypr/conf.d/90-hyprscrolling.conf";

  dropInConf = ''
    # Managed by Nix: programs.hyprscrolling
    # Load plugin shared object (.so)
    plugin = ${stableSoPath}

    ${lib.optionalString cfg.setAsDefaultLayout ''
    general {
      layout = scrolling
    }
    ''}

    ${renderSettings cfg.settings}

    ${cfg.extraConfig}
  '';
in
{
  options.programs.hyprscrolling = {
    enable = lib.mkEnableOption "Hyprland hyprscrolling (scrolling layout) plugin (NixOS-friendly)";

    pluginPackage = lib.mkOption {
      type = lib.types.nullOr lib.types.package;
      default = defaultPluginPkg;
      description = ''
        Package that provides the hyprscrolling plugin.
        Defaults to pkgs.hyprlandPlugins.hyprscrolling when available.
      '';
    };

    setAsDefaultLayout = lib.mkOption {
      type = lib.types.bool;
      default = true;
      description = "Whether to set `general { layout = scrolling }` in the generated drop-in config.";
    };

    settings = lib.mkOption {
      type = lib.types.attrs;
      default = { };
      description = ''
        Attribute set rendered into a `plugin:hyprscrolling { ... }` block
        in the generated drop-in config.
      '';
    };

    extraConfig = lib.mkOption {
      type = lib.types.lines;
      default = "";
      description = "Extra Hyprland config appended to the generated drop-in config.";
    };

    # Where we install the generated config snippet (so you can `source = ...` it)
    dropInPath = lib.mkOption {
      type = lib.types.str;
      default = dropInConfPath;
      description = "Path to the generated Hyprland drop-in config file (needs to be sourced by your hyprland.conf).";
    };

    # Where we install a stable symlink to the plugin .so
    stablePluginSoPath = lib.mkOption {
      type = lib.types.str;
      default = stableSoPath;
      description = "Stable path for the plugin shared object (symlinked to the Nix store).";
    };
  };

  config = lib.mkIf cfg.enable {
    assertions = [
      {
        assertion = cfg.pluginPackage != null;
        message = ''
          Could not find hyprscrolling plugin package in this nixpkgs.
          Set programs.hyprscrolling.pluginPackage explicitly (e.g. pkgs.hyprlandPlugins.hyprscrolling).
        '';
      }
    ];

    # Ensure the plugin is built and available.
    environment.systemPackages = [ cfg.pluginPackage ];

    # Provide a stable .so path under /etc (no /nix/store hardcoding in hyprland.conf)
    environment.etc."hypr/plugins/libhyprscrolling.so".source =
      "${cfg.pluginPackage}/lib/libhyprscrolling.so";

    # Provide a drop-in config file under /etc.
    environment.etc."hypr/conf.d/90-hyprscrolling.conf".text = dropInConf;
  };
}