# frozen_string_literal: true

module Gitlab
  class RackTimeoutObserver
    def initialize
      @counter = Gitlab::Metrics.counter(:rack_state_total, 'Number of requests in a given rack state')
    end

    # returns the Proc to be used as the observer callback block
    def callback
      method(:log_timeout_exception)
    end

    private

    def log_timeout_exception(env)
      info = env[::Rack::Timeout::ENV_INFO_KEY]
      return unless info

      @counter.increment(labels(info, env))
    end

    def labels(info, env)
      params = controller_params(env) || grape_params(env) || {}

      {
        controller: params['controller'],
        action: params['action'],
        route: params['route'],
        state: info.state
      }
    end

    def controller_params(env)
      env['action_dispatch.request.parameters']
    end

    def grape_params(env)
      endpoint = env[Grape::Env::API_ENDPOINT]
      route = endpoint&.route&.pattern&.origin
      return unless route

      { 'route' => route }
    end
  end
end