module Reality
  module Util
    module_function

    def oneify(val)
      return val unless val.is_a?(Array)
      val.size <= 1 ? val.first : val
    end

    def dig(what, *keys)
      return what if keys.empty?
      k = keys.shift
      if k == :*
        what.map { |el| dig(el, *keys) }
      else
        what.respond_to?(:[]) or fail ArgumentError, "Can't dig(#{keys}) in #{what.class}"
        res = what[k] or return nil
        dig(res, *keys)
      end
    end

    DEFAULT_REQUIRE_EXPLANATION = 'Please install `%s` in order to use this functionality.'.freeze

    def require_optional(gem, explanation = nil)
      require gem
    rescue LoadError
      raise LoadError, explanation || DEFAULT_REQUIRE_EXPLANATION % gem
    end
  end
end