oauth_state_routing_constraint.rb

class OAuthState
  attr_reader :request

  def initialize(request)
    @request = request
  end

  def match_and_unpack_state
    match?.tap { unpack_state }
  end

  def self.matches?(request)
    self.new(request).match_and_unpack_state
  end

  private

  def unpack_state
    request.params.delete(:state)

    self.class.params.zip(ordered_params[1..-1]) do |param, value|
      request.params[param] = value
    end
  end

  def match?
    action == self.class.action
  end

  def ordered_params
    @ordered_params ||= @request.params.fetch(:state).split(",")
  end

  def action
    ordered_params.first
  end
end

class ConnectionState < OAuthState
  def self.action
    'connect'
  end

  def self.params
    %i( project_id is_production )
  end
end