module Pagy::UrlHelpers

def pagy_set_query_params(page, vars, params)

Overridable by the jsonapi extra
Add the page and items params 
def pagy_set_query_params(page, vars, params)
  params[vars[:page_param].to_s]  = page
  params[vars[:items_param].to_s] = vars[:items] if vars[:items_extra]
end

def pagy_url_for(pagy, page, absolute: false, **_)

For non-rack environments you can use the standalone extra
It supports all Rack-based frameworks (Sinatra, Padrino, Rails, ...).
Return the URL for the page, relying on the params method and Rack by default. 
def pagy_url_for(pagy, page, absolute: false, **_)
  vars         = pagy.vars
  request_path = vars[:request_path].to_s.empty? ? request.path : vars[:request_path]
  pagy_params  = pagy.params.is_a?(Hash) ? pagy.params.transform_keys(&:to_s) : {}
  params       = request.GET.merge(pagy_params)
  pagy_set_query_params(page, vars, params)
  params       = pagy.params.call(params) if pagy.params.is_a?(Proc)
  query_string = "?#{Rack::Utils.build_nested_query(params)}"
  "#{request.base_url if absolute}#{request_path}#{query_string}#{vars[:fragment]}"
end