class Restforce::Middleware::Authentication

the oauth access token (if a refresh token is present).
will attempt to either reauthenticate (username and password) or refresh
When a request fails (ie. A status of 401 is returned). The middleware
Faraday middleware that allows for on the fly authentication of requests.

def authenticate! 

def authenticate!
  response = connection.post '/services/oauth2/token' do |req|
    req.body = URI.encode_www_form params
  end
  raise Restforce::AuthenticationError, error_message(response) if response.status != 200
  @options[:instance_url] = response.body['instance_url']
  @options[:oauth_token]  = response.body['access_token']
  response.body
end

def call(env) 

def call(env)
  @app.call(env)
rescue Restforce::UnauthorizedError
  authenticate!
  raise
end

def connection 

def connection
  @connection ||= Faraday.new(:url => "https://#{@options[:host]}") do |builder|
    builder.use Restforce::Middleware::Mashify, nil, @options
    builder.response :json
    builder.use Restforce::Middleware::Logger, Restforce.configuration.logger, @options if Restforce.log?
    builder.adapter Faraday.default_adapter
  end
end

def error_message(response) 

def error_message(response)
  "#{response.body['error']}: #{response.body['error_description']}"
end

def params 

def params
  raise 'not implemented'
end