/*
 *
 * Copyright 2015 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#ifndef GRPC_CORE_LIB_IOMGR_POLLING_ENTITY_H
#define GRPC_CORE_LIB_IOMGR_POLLING_ENTITY_H

#include <grpc/support/port_platform.h>

#include "src/core/lib/iomgr/pollset.h"
#include "src/core/lib/iomgr/pollset_set.h"
#include "src/core/lib/promise/context.h"

typedef enum grpc_pollset_tag {
  GRPC_POLLS_NONE,
  GRPC_POLLS_POLLSET,
  GRPC_POLLS_POLLSET_SET
} grpc_pollset_tag;

/* A grpc_polling_entity is a pollset-or-pollset_set container. It allows
 * functions that accept a pollset XOR a pollset_set to do so through an
 * abstract interface. No ownership is taken. */

struct grpc_polling_entity {
  union {
    grpc_pollset* pollset = nullptr;
    grpc_pollset_set* pollset_set;
  } pollent;
  grpc_pollset_tag tag = GRPC_POLLS_NONE;
};

grpc_polling_entity grpc_polling_entity_create_from_pollset_set(
    grpc_pollset_set* pollset_set);
grpc_polling_entity grpc_polling_entity_create_from_pollset(
    grpc_pollset* pollset);

/** If \a pollent contains a pollset, return it. Otherwise, return NULL */
grpc_pollset* grpc_polling_entity_pollset(grpc_polling_entity* pollent);

/** If \a pollent contains a pollset_set, return it. Otherwise, return NULL */
grpc_pollset_set* grpc_polling_entity_pollset_set(grpc_polling_entity* pollent);

bool grpc_polling_entity_is_empty(const grpc_polling_entity* pollent);

/** Add the pollset or pollset_set in \a pollent to the destination pollset_set
 * \a * pss_dst */
void grpc_polling_entity_add_to_pollset_set(grpc_polling_entity* pollent,
                                            grpc_pollset_set* pss_dst);

/** Delete the pollset or pollset_set in \a pollent from the destination
 * pollset_set \a * pss_dst */
void grpc_polling_entity_del_from_pollset_set(grpc_polling_entity* pollent,
                                              grpc_pollset_set* pss_dst);

namespace grpc_core {
template <>
struct ContextType<grpc_polling_entity> {};
}  // namespace grpc_core

#endif /* GRPC_CORE_LIB_IOMGR_POLLING_ENTITY_H */
