#pragma once

#include <chrono>

#include <functional>

#include "envoy/common/callback.h"

#include "envoy/common/pure.h"

#include "absl/base/attributes.h"

#include "absl/status/status.h"

namespace Envoy {

namespace Network {

enum class DrainDirection {

  /**

   * Not draining yet. Default value, should not be externally set.

   */

  None = 0,

  /**

   * Drain inbound connections only.

   */

  InboundOnly,

  /**

   * Drain both inbound and outbound connections.

   */

  All,

};

class DrainDecision {

public:

  using DrainCloseCb = std::function<absl::Status(std::chrono::milliseconds)>;

  /**

   * @return TRUE if a connection should be drained and closed. It is up to individual network

   *         filters to determine when this should be called for the least impact possible.

   * @param direction supplies the direction for which the caller is checking drain close.

   */

  virtual bool drainClose(DrainDirection scope) const PURE;

  /**

   * @brief Register a callback to be called proactively when a drain decision enters into a

   *        'close' state.

   *        NOTE: this API is used in prorietary builds of Envoy and can not be decommissioned.

   *        TODO(yanavlasov): cleanup unused parts of this change without removing this API.

   *

   * @param cb Callback to be called once drain decision enters close state

   * @return handle to remove callback

   */

  ABSL_MUST_USE_RESULT

  virtual Common::CallbackHandlePtr addOnDrainCloseCb(DrainDirection scope,

                                                      DrainCloseCb cb) const PURE;

};

} // namespace Network

} // namespace Envoy