/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 *   Copyright 2022-Present Couchbase, Inc.
 *
 *   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

#include <condition_variable>
#include <functional>
#include <list>
#include <mutex>
#include <string>
#include <system_error>

namespace couchbase::core::mcbp
{
class queue_request;
class operation_consumer;

class operation_queue : public std::enable_shared_from_this<operation_queue>
{
  public:
    using drain_callback = std::function<void(std::shared_ptr<queue_request> request)>;

    [[nodiscard]] auto push(std::shared_ptr<queue_request> request, std::size_t max_items) -> std::error_code;
    auto remove(std::shared_ptr<queue_request> request) -> bool;
    void drain(drain_callback callback);

    [[nodiscard]] auto consumer() -> std::shared_ptr<operation_consumer>;
    void close();
    [[nodiscard]] auto debug_string() const -> std::string;

  private:
    void close_consumer(std::shared_ptr<operation_consumer> consumer);
    auto pop(std::shared_ptr<operation_consumer> consumer) -> std::shared_ptr<queue_request>;
    auto items_to_drain() -> std::list<std::shared_ptr<queue_request>>;

    std::list<std::shared_ptr<queue_request>> items_{};
    mutable std::mutex mutex_{};
    std::condition_variable signal_{};
    bool is_open_{ true };

    friend operation_consumer;
};
} // namespace couchbase::core::mcbp
