Proof-of-concept web service client

client.rb

require 'net/http'
require 'json'

class Client
  class << self
    attr_accessor :host, :port, :api_key, :version
  end

  self.host    = ENV['ORDERS_API_HOST'] || 'api.orders.com'
  self.port    = ENV['ORDERS_API_PORT'] || 80
  self.api_key = ENV['ORDERS_API_KEY']
  self.version = ENV['ORDERS_API_VERSION']

  def self.search(term, opts = {})
    api(:get, '/search', {term: term}.merge(opts))
  end

  def self.add_filter(&block)
    filters.push(block)
  end

  private

  def self.filters
    @filters ||= []
  end

  def self.api(method, path, opts = {})
    response = remote_request(method, path, opts)
    # In case (get it?!) we decide to handle individual response types
    case response
    when Net::HTTPSuccess
      body = JSON.parse(response.body)
      body.respond_to?(:map) ? body.map { |e| filtered(e) } : filtered(body)
    else
      nil
    end
  end

  def self.remote_request(method, path, params = {})
    params   = URI.encode_www_form(params)
    response = Net::HTTP.start(host, port) do |http|
      case method
      when :get
        http.get("#{path}?#{params}", headers)
      when :post
        http.post(path, params, headers)
      end
    end
  end

  def self.headers
    {
      'accept'         => "application/vnd.orders.api.json; version=#{version}",
      'orders_api_key' => api_key
    }
  end

  def self.filtered(value)
    filters.inject(value) { |m, f| f.call(m) }
  end
end