#pragma once

#include "envoy/event/dispatcher.h"

#include "envoy/event/timer.h"

#include "absl/container/flat_hash_set.h"

#include "datadog/event_scheduler.h"

#include "nlohmann/json.hpp"

namespace Envoy {

namespace Extensions {

namespace Tracers {

namespace Datadog {

/**

 * Registry of recurring events (timers). This class implements dd-trace-cpp's

 * \c datadog::tracing::EventScheduler interface in terms of an

 * \c Event::Dispatcher, which is what is used by Envoy. An instance of this class

 * is passed into dd-trace-cpp when tracing is configured, allowing dd-trace-cpp

 * to periodically send batches of traces to the Datadog Agent.

 */

class EventScheduler : public datadog::tracing::EventScheduler {

public:

  explicit EventScheduler(Event::Dispatcher& dispatcher);

  /**

   * Repeatedly execute the specified \p callback with approximately \p interval

   * between each invocation, starting after an initial \p interval. Return a

   * function that cancels future invocations. If the returned function is

   * invoked after this \c EventScheduler is destroyed, the behavior is

   * undefined.

   * @param interval how often the event will occur

   * @param callback the function invoked when the event occurs

   * @return a zero-parameter function that cancels the recurring event

   */

  Cancel schedule_recurring_event(std::chrono::steady_clock::duration interval,

                                  std::function<void()> callback) override;

  // Implementation of the required config() method from datadog::tracing::EventScheduler

  std::string config() const override;

  // Provides JSON configuration for debug logging.

  const nlohmann::json& config_json() const;

private:

  Event::Dispatcher& dispatcher_;

  absl::flat_hash_set<Event::TimerPtr> timers_;

};

} // namespace Datadog

} // namespace Tracers

} // namespace Extensions

} // namespace Envoy