#22 Code Reading - The Twitter Gem

# README.mkd

Twitter.configure do |config|
  config.consumer_key = YOUR_CONSUMER_KEY
  config.consumer_secret = YOUR_CONSUMER_SECRET
  ...
end
________________________________________

# configuration.rb

module Twitter
  module Configuration
    VALID_OPTIONS_KEYS = [:consumer_key, ...]
    ...
    attr_accessor *VALID_OPTIONS_KEYS
    
    def self.extended(base)
      base.reset
    end

    def configure
      yield self
    end

    def options
      VALID_OPTIONS_KEYS.inject({}){|o, k| o.merge!(k => send(k))}
    end
    
    def reset
      self.adapter = DEFAULT_ADAPTER
      ...
    end
________________________________________

# twitter.rb

module Twitter
  extend Configuration

# twitter.rb

module Twitter
  extend Configuration

  def self.client(options={})
    Twitter::Client.new(options)
  end

  def self.method_missing(method, *args, &block)
    return super unless client.respond_to?(method)
    client.send(method, *args, &block)
  end
end
________________________________________

# Rails Console

> Twitter.user('arailsdemo')
  => <#Hashie::Mash contributors_enabled=false ...>
> Twitter.foo
  => NoMethodError: undefined method `foo' for Twitter:Module

# client.rb

module Twitter
  class Client < API
    ...
    include Twitter::Client::Tweets
    ...
    include Twitter::Client::User
    ...
________________________________________

# api.rb

module Twitter
  class API
    attr_accessor *Configuration::VALID_OPTIONS_KEYS

    def initialize(options={})
      options = Twitter.options.merge(options)
      Configuration::VALID_OPTIONS_KEYS.each do |key|
        send("#{key}=", options[key])
      end
    end

    include Connection
    include Request
    include Authentication

# README.mkd

client = Twitter::Client.new
client.update("I just posted a status update via the Twitter Ruby Gem!")
________________________________________

# configuration.rb

module Twitter
  module Configuration
    ...
    DEFAULT_ENDPOINT        = 'https://api.twitter.com/1/'.freeze
________________________________________

# tweets.rb

module Twitter
  class Client
    module Tweets
      ...
      def update(status, options={})
        response = post('statuses/update', options.merge(:status => status))
        format.to_s.downcase == 'xml' ? response['status'] : response
      end
________________________________________

# request.rb

module Twitter
  module Request
    ...
    def post(path, options={}, raw=false)
      request(:post, path, options, raw)
    end

    private

    def request(method, path, options, raw)
      response = connection(raw).send(method) do |request|
        ...

# connection.rb

require 'faraday_middleware'

module Twitter
  module Connection
    private

    def connection(raw=false)
      options = {
        :headers => {'Accept' => "application/#{format}", 'User-Agent' => user_agent},
        :proxy => proxy,
        :ssl => {:verify => false},
        :url => api_endpoint,
      }

      Faraday::Connection.new(options) do |connection|
        connection.use Faraday::Request::Multipart
        connection.use Faraday::Request::OAuth, authentication if authenticated?
        connection.adapter(adapter)
        connection.use Faraday::Response::RaiseHttp5xx
        connection.use Faraday::Response::Parse unless raw
        connection.use Faraday::Response::RaiseHttp4xx
        connection.use Faraday::Response::Mashify unless raw
      end
    end
  end
________________________________________

# autentication.rb

module Twitter
  module Authentication
    private

    def authentication
      {
        :consumer_key => consumer_key,
        :consumer_secret => consumer_secret,
        :token => oauth_token,
        :token_secret => oauth_token_secret
      }
    end

    def authenticated?
      authentication.values.all?
    end
  end
end
________________________________________

# oauth.rb

require 'faraday'
require 'simple_oauth'

module Faraday
  class Request::OAuth < Faraday::Middleware
    def call(env)
      params = env[:body].is_a?(Hash) ? env[:body] : {}
      signature_params = params.reject{|k,v| v.respond_to?(:content_type) }
      header = SimpleOAuth::Header.new(env[:method], env[:url], signature_params, @options)

      env[:request_headers]['Authorization'] = header.to_s

      @app.call(env)
    end

    def initialize(app, options)
      @app, @options = app, options
    end
  end
end

# request.rb

module Twitter
  module Request
    ...
    private

    def request(method, path, options, raw)
      response = connection(raw).send(method) do |request|
        case method
        when :get, :delete
          request.url(formatted_path(path), options)
        when :post, :put
          request.path = formatted_path(path)
          request.body = options
        end
      end
      raw ? response : response.body
    end

    def formatted_path(path)
      [path, format].compact.join('.')
    end
________________________________________

# connection.rb

module Faraday
  class Connection
    ...
    def post(url = nil, body = nil, headers = nil, &block)
      run_request(:post, url, body, headers, &block)
    end
    ...
    def run_request(method, url, body, headers)
      if !METHODS.include?(method)
        raise ArgumentError, "unknown http method: #{method}"
      end

      Request.run(self, method) do |req|
        req.url(url) if url
        req.headers.update(headers) if headers
        req.body = body if body
        yield req if block_given?
      end
    end

> client = Twitter.client
> response = client.update('test')
  => <#Hashie::Mash contributors=nil coordinates=nil ...>
> response.user.url
  => "http://www.arailsdemo.com"

> Twitter.oauth_token = 'bad_token'
> client = Twitter.client
> client.update('test')
  => Twitter::Unauthorized: POST https://api.twitter.com/1/statuses/update.json: 401 Unauthorized: Invalid / expired Token ...