Use Ruby's SimpleDelegator to implement middleware

middleware.rb

# frozen_string_literal: true

require 'delegate'
require 'json'

class Middleware < SimpleDelegator
end

class CacheMiddleware < Middleware
  def initialize(object)
    super
    @cache = {}
  end

  def call(*args, **params)
    endpoint, = args
    return @cache[endpoint] if @cache[endpoint]

    super
  end
end

class RetryMiddleware < Middleware
  def call(*args, **params)
    retry_count = 0
    begin
      super
    rescue StandardError
      raise if retry_count >= 3

      retry_count += 1
      retry
    end
  end
end

class Client
  def now_time
    call('/now_time')
  end

  def call(*_args, **_params)
    # Fake API Response
    { timestamp: Time.now.to_i }.to_json
  end
end

client = [CacheMiddleware, RetryMiddleware].reduce(Client.new) do |client, middleware|
  middleware.new(client)
end

puts client.now_time
# Cached
puts client.now_time