{ config, lib, pkgs, ... }: with lib; let cfg = config.programs.feh; bindingsOf = t: with types; attrsOf (nullOr (either t (listOf t))); renderBindings = bindings: let enabled = filterAttrs (n: v: v != null) bindings; disabled = filterAttrs (n: v: v == null) bindings; render = mapAttrsToList renderBinding; in concatStringsSep "\n" (render disabled ++ render enabled); renderBinding = func: key: if key == null then func else if isList key then concatStringsSep " " ([ func ] ++ map toString key) else "${func} ${toString key}"; in { options.programs.feh = { enable = mkEnableOption "feh - a fast and light image viewer"; buttons = mkOption { default = { }; type = with types; bindingsOf (either str int); example = { zoom_in = 4; zoom_out = "C-4"; prev_img = [ 3 "C-3" ]; }; description = '' Override feh's default mouse button mapping. If you want to disable an action, set its value to null. If you want to bind multiple buttons to an action, set its value to a list. See <link xlink:href="https://man.finalrewind.org/1/feh/#x425554544f4e53"/> for default bindings and available commands. ''; }; keybindings = mkOption { default = { }; type = bindingsOf types.str; example = { zoom_in = "plus"; zoom_out = "minus"; prev_img = [ "h" "Left" ]; }; description = '' Override feh's default keybindings. If you want to disable a keybinding set its value to null. If you want to bind multiple keys to an action, set its value to a list. See <link xlink:href="https://man.finalrewind.org/1/feh/#x4b455953"/> for default bindings and available commands. ''; }; }; config = mkIf cfg.enable { assertions = [{ assertion = ((filterAttrs (n: v: v == "") cfg.keybindings) == { }); message = "To disable a keybinding, use `null` instead of an empty string."; }]; home.packages = [ pkgs.feh ]; xdg.configFile."feh/buttons" = mkIf (cfg.buttons != { }) { text = renderBindings cfg.buttons + "\n"; }; xdg.configFile."feh/keys" = mkIf (cfg.keybindings != { }) { text = renderBindings cfg.keybindings + "\n"; }; }; }