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

let
  cfg = config.my.wallpapers;
  args = lib.concatStringsSep " " (lib.mapAttrsToList
    (monitor: img: "--output ${monitor} --zoom ${lib.escapeShellArg img}") cfg);
in
{
  options.my.wallpapers = lib.mkOption {
    type = lib.types.attrsOf lib.types.path;
    default = { };
    description = "Wallpaper image per monitor output name.";
  };

  config = lib.mkIf (cfg != { }) {
    home.packages = [ pkgs.xwallpaper ];

    xdg.configFile."wallpaper/set.sh" = {
      executable = true;
      text = ''
        #!/bin/sh
        ${pkgs.xwallpaper}/bin/xwallpaper ${args}
      '';
    };
  };
}