module Qtpay
  module Sign
    def self.generate(params, options = {})
      params = Utils.stringify_keys(params)
      key = options[:server_key] || Qtpay.server_key
      string = params_to_string(params)

      sign(key, string)

    end
    
    def self.verify?(params, options = {})
      params = Utils.stringify_keys(params)

      sign_type = params.delete('sign_type')
      sign = params.delete('sign')
      string = params_to_string(params)

      key = options[:server_key] || Qtpay.server_key

      sign == sign(key, string)
    end

    def self.sign(key, string)
      Digest::MD5.hexdigest("#{string}#{key}")
    end

    def self.params_to_string(params)
      params.sort.map { |item| item.join('=') }.join('&')
    end
  end
end