/*
 * Copyright (c) 2017-2019 Cisco and/or its affiliates.
 * 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.
 */

#pragma once

// TODO
#include <hicn/transport/utils/spinlock.h>

#include <deque>
#include <memory>
#include <mutex>

namespace utils {

template <typename T>
class ObjectPool {
  class ObjectDeleter {
   public:
    ObjectDeleter(ObjectPool<T> *pool = nullptr) : pool_(pool) {}

    void operator()(T *t) {
      if (pool_) {
        pool_->add(t);
      } else {
        delete t;
      }
    }

   private:
    ObjectPool<T> *pool_;
  };

 public:
  using Ptr = std::unique_ptr<T, ObjectDeleter>;

  ObjectPool() : destructor_(false) {}

  ~ObjectPool() { destructor_ = true; }

  std::pair<bool, Ptr> get() {
    if (object_pool_.empty()) {
      return std::make_pair<bool, Ptr>(false, makePtr(nullptr));
    }

    utils::SpinLock::Acquire locked(object_pool_lock_);
    auto ret = std::move(object_pool_.front());
    object_pool_.pop_front();
    return std::make_pair<bool, Ptr>(true, std::move(ret));
  }

  void add(T *object) {
    utils::SpinLock::Acquire locked(object_pool_lock_);

    if (TRANSPORT_EXPECT_TRUE(!destructor_)) {
      object_pool_.emplace_back(makePtr(object));
    }
  }

  Ptr makePtr(T *object) { return Ptr(object, ObjectDeleter(this)); }

 private:
  // No copies
  ObjectPool(const ObjectPool &other) = delete;

  utils::SpinLock object_pool_lock_;
  std::deque<Ptr> object_pool_;
  bool destructor_;
};

}  // namespace utils