#pragma once

#include <memory>

#include "envoy/event/dispatcher.h"

#include "envoy/event/timer.h"

#include "envoy/http/http_server_properties_cache.h"

namespace Envoy {

namespace Http {

// Tracks the status of HTTP/3 being broken for a period of time

// subject to exponential backoff.

class Http3StatusTrackerImpl : public HttpServerPropertiesCache::Http3StatusTracker {

public:

  explicit Http3StatusTrackerImpl(Event::Dispatcher& dispatcher);

  // Returns true if HTTP/3 status is pending.

  bool isHttp3Pending() const override;

  // Returns true if HTTP/3 is broken.

  bool isHttp3Broken() const override;

  // Returns true if HTTP/3 is confirmed to be working.

  bool isHttp3Confirmed() const override;

  // Returns true if HTTP/3 has failed recently.

  bool hasHttp3FailedRecently() const override;

  // Marks HTTP/3 status as pending.

  void markHttp3Pending() override;

  // Marks HTTP/3 broken for a period of time, subject to backoff.

  void markHttp3Broken() override;

  // Marks HTTP/3 as confirmed to be working and resets the backoff timeout.

  void markHttp3Confirmed() override;

  // Marks HTTP/3 as failed recently.

  void markHttp3FailedRecently() override;

private:

  enum class State {

    Pending,

    FailedRecently,

    Broken,

    Confirmed,

  };

  // Called when the expiration timer fires.

  void onExpirationTimeout();

  State state_{State::Pending};

  // The number of consecutive times HTTP/3 has been marked broken.

  int consecutive_broken_count_{};

  // The timer which tracks when HTTP/3 broken status should expire

  Event::TimerPtr expiration_timer_;

};

} // namespace Http

} // namespace Envoy