#pragma once

#include <functional>

#include <memory>

#include "envoy/common/pure.h"

namespace Envoy {

namespace Event {

/**

 * Callback wrapper that allows direct scheduling of callbacks in the event loop.

 */

class SchedulableCallback {

public:

  /**

   * Schedule the callback so it runs in the current iteration of the event loop after all events

   * scheduled in the current event loop have had a chance to execute.

   */

  virtual void scheduleCallbackCurrentIteration() PURE;

  /**

   * Schedule the callback so it runs in the next iteration of the event loop. There are no

   * ordering guarantees for callbacks scheduled for the next iteration, not even among

   * next-iteration callbacks.

   */

  virtual void scheduleCallbackNextIteration() PURE;

  /**

   * Cancel pending execution of the callback.

   */

  virtual void cancel() PURE;

  /**

   * Return true whether the SchedulableCallback is scheduled for execution.

   */

  virtual bool enabled() PURE;

};

using SchedulableCallbackPtr = std::unique_ptr<SchedulableCallback>;

/**

 * SchedulableCallback factory.

 */

class CallbackScheduler {

public:

  /**

   * Create a schedulable callback.

   */

  virtual SchedulableCallbackPtr createSchedulableCallback(const std::function<void()>& cb) PURE;

};

} // namespace Event

} // namespace Envoy