Upcoach MD5 Request Validator for Rubyist

upcoach_request_validator.rb

# frozen_string_literal: true

module UpcoachService
  class RequestValidator < ApplicationService
    def initialize(full_url, signing_secret)
      @full_url = full_url
      @signing_secret = signing_secret
    end

    def call
      validate!

      hash == signature
    end

    private

    def hash
      Digest::MD5.hexdigest("#{clean_url}::#{expires}::#{@signing_secret}")
    end

    def query_params
      @query_params ||= Rack::Utils.parse_nested_query(
        URI.parse(@full_url).query
      )
    end

    def clean_url
      @full_url
        .split('&')
        .map { |p| p.split('=') }
        .filter { |sp| %w[signature expires].exclude?(sp.first) }
        .map { |sp| sp.join('=') }
        .join('&')
    end

    def signature
      query_params['signature']
    end

    def expires
      query_params['expires']
    end

    def validate!
      raise ArgumentError, 'full_url can\'t be blank' if @full_url.blank?
      raise ArgumentError, 'signing_secret can\'t be blank' if @signing_secret.blank?
      raise ArgumentError, 'full_url is not valid' unless @full_url.match(
        URI::DEFAULT_PARSER.make_regexp(%w[http https])
      )
    end
  end
end

If you are not using Service Objects, you can implement a basic ApplicationService as below.

# frozen_string_literal: true

class ApplicationService
  def self.call(...)
    new(...).call
  end
end