#pragma once

#include <chrono>

#include <functional>

#include <vector>

#include "envoy/common/time.h"

#include "envoy/config/listener/v3/listener.pb.h"

#include "envoy/event/dispatcher.h"

#include "envoy/event/timer.h"

#include "envoy/server/drain_manager.h"

#include "envoy/server/instance.h"

#include "source/common/common/callback_impl.h"

#include "source/common/common/logger.h"

namespace Envoy {

namespace Server {

/**

 * Implementation of drain manager that does the following by default:

 * 1) Terminates the parent process after 15 minutes.

 * 2) Drains the parent process over a period of 10 minutes where drain close becomes more

 *    likely each second that passes.

 */

class DrainManagerImpl : Logger::Loggable<Logger::Id::main>, public DrainManager {

public:

  DrainManagerImpl(Instance& server, envoy::config::listener::v3::Listener::DrainType drain_type,

                   Event::Dispatcher& dispatcher);

  // Network::DrainDecision

  bool drainClose(Network::DrainDirection scope) const override;

  Common::CallbackHandlePtr addOnDrainCloseCb(Network::DrainDirection direction,

                                              DrainCloseCb cb) const override;

  // Server::DrainManager

  void startDrainSequence(Network::DrainDirection direction,

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

  void startParentShutdownSequence() override;

  DrainManagerPtr

  createChildManager(Event::Dispatcher& dispatcher,

                     envoy::config::listener::v3::Listener::DrainType drain_type) override;

  DrainManagerPtr createChildManager(Event::Dispatcher& dispatcher) override;

private:

  void addDrainCompleteCallback(Network::DrainDirection direction, std::function<void()> cb);

  Instance& server_;

  Event::Dispatcher& dispatcher_;

  const envoy::config::listener::v3::Listener::DrainType drain_type_;

  using DrainPair = struct {

    bool first;

    Network::DrainDirection second;

  };

  std::atomic<DrainPair> draining_{DrainPair{false, Network::DrainDirection::None}};

  // A map of timers keyed by the direction that triggered the drain

  std::map<Network::DrainDirection, Event::TimerPtr> drain_tick_timers_;

  std::map<Network::DrainDirection, MonotonicTime> drain_deadlines_ = {

      {Network::DrainDirection::InboundOnly, MonotonicTime()},

      {Network::DrainDirection::All, MonotonicTime()}};

  mutable Common::CallbackManager<absl::Status, std::chrono::milliseconds> cbs_{};

  std::vector<std::function<void()>> drain_complete_cbs_;

  // Callbacks called by startDrainSequence to cascade/proxy to children

  std::shared_ptr<Common::ThreadSafeCallbackManager> children_;

  // Callback handle parent will invoke to initiate drain-sequence. Created and set

  // by the parent drain-manager.

  Common::CallbackHandlePtr parent_callback_handle_;

  Event::TimerPtr parent_shutdown_timer_;

};

} // namespace Server

} // namespace Envoy