{ config, lib, pkgs, ... }: with lib; let 

  userOpts = { name, config, ... }: {
    options = {
      homeSize = mkOption {
        type = types.nullOr types.str;
        description = "Size of user's home directory";
        default = null;
      };
      homeProjectId = mkOption {
        type = types.nullOr types.int;
        description = "What project does this user's home directory belong to";
        default = null;
      };
    };
    config = {
    };
  };

in {
  options = {
    users.users = mkOption {
      type = with types; attrsOf (submodule userOpts);
    };
  };

  config = let 
    users' = lib.attrsets.filterAttrs (userName: user: user.homeSize != null) config.users.users;
  in mkIf (users' != {}) {
    programs.xfs_quota.projects = mapAttrs (userName: user: let 
    in {
      id = user.homeProjectId;
      fileSystem = "/";
      path = user.home;
      sizeSoftLimit = user.homeSize;
      sizeHardLimit = user.homeSize;
    }) users';
  };
}