hook.rb

class Hook
  attr_reader :payload

  def initialize(payload)
    @payload = payload
  end

  def operation_attributes
    send(:"#{action}_operation_attributes")
  end

  def action
    case
    when create_or_push? then Operation::Actions.deploy
    when delete?         then Operation::Actions.teardown
    end
  end

  def branch
    payload['ref'].match(/[^\/]+\Z/).to_s
  end

protected

  def create_or_push?
    payload.fetch('created') ||
      !payload.fetch('created') && !payload.fetch('deleted')
  end

  def delete?
    payload.fetch('deleted')
  end

  def deploy_operation_attributes
    {
      action: action,
      head_commit_id: head_commit['id'],
      head_commit_url: head_commit['url']
    }
  end

  def teardown_operation_attributes
    {action: action}
  end

  def head_commit
    payload['head_commit']
  end
end