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

let

  cfg = config.programs.qcal;

  qcalAccounts = lib.attrValues (
    lib.filterAttrs (_: a: a.qcal.enable) config.accounts.calendar.accounts
  );

  filteredAccounts =
    let
      mkAccount =
        account:
        lib.filterAttrs (_: v: v != null) (
          with account.remote;
          {
            Url = url;
            Username = if userName == null then null else userName;
            PasswordCmd = if passwordCommand == null then null else toString passwordCommand;
          }
        );
    in
    map mkAccount qcalAccounts;

in
{
  meta.maintainers = with lib.maintainers; [ antonmosich ];

  options = {
    programs.qcal = {
      enable = lib.mkEnableOption "qcal, a CLI calendar application";

      package = lib.mkPackageOption pkgs "qcal" { nullable = true; };

      timezone = lib.mkOption {
        type = lib.types.singleLineStr;
        default = "Local";
        example = "Europe/Vienna";
        description = "Timezone to display calendar entries in";
      };

      defaultNumDays = lib.mkOption {
        type = lib.types.ints.positive;
        default = 30;
        description = "Default number of days to show calendar entries for";
      };
    };

    accounts.calendar.accounts = lib.mkOption {
      type =
        with lib.types;
        attrsOf (submodule {
          options.qcal.enable = lib.mkEnableOption "qcal access";
        });
    };
  };

  config = lib.mkIf cfg.enable {
    home.packages = lib.mkIf (cfg.package != null) [ cfg.package ];

    xdg.configFile."qcal/config.json".source =
      let
        jsonFormat = pkgs.formats.json { };
      in
      jsonFormat.generate "qcal.json" {
        DefaultNumDays = cfg.defaultNumDays;
        Timezone = cfg.timezone;
        Calendars = filteredAccounts;
      };
  };
}