// Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).

//

// 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.

/**

 * @file ResourceEvent.h

 *

 */

#ifndef FASTDDS_RTPS_RESOURCES__RESOURCEEVENT_H

#define FASTDDS_RTPS_RESOURCES__RESOURCEEVENT_H

#ifndef DOXYGEN_SHOULD_SKIP_THIS_PUBLIC

#include <atomic>

#include <functional>

#include <memory>

#include <vector>

#include <fastdds/rtps/attributes/ThreadSettings.hpp>

#include <fastdds/utils/TimedMutex.hpp>

#include <fastdds/utils/TimedConditionVariable.hpp>

namespace eprosima {

class thread;

namespace fastdds {

namespace rtps {

class TimedEventImpl;

/**

 * This class centralizes all operations over timed events in the same thread.

 * @ingroup MANAGEMENT_MODULE

 */

class ResourceEvent

{

public:

    ResourceEvent();

    ~ResourceEvent();

    /*!

     * @brief Method to initialize the internal thread.

     *

     * @param [in]  thread_cfg  Settings to apply to the created thread.

     * @param [in]  name_fmt    A null-terminated string to be used as the format argument of

     *                         a `snprintf` like function, taking `thread_id` as additional

     *                         argument, and used to give a name to the created thread.

     * @param [in]  thread_id   Single variadic argument passed to the formatting function.

     */

    void init_thread(

            const fastdds::rtps::ThreadSettings& thread_cfg = {},

            const char* name_fmt = "event %u",

            uint32_t thread_id = 0);

    void stop_thread();

    /*!

     * @brief This method informs that a TimedEventImpl has been created.

     *

     * This method has to be called when creating a TimedEventImpl object.

     * @param event TimedEventImpl object that has been created.

     */

    void register_timer(

            TimedEventImpl* event);

    /*!

     * @brief This method removes a TimedEventImpl object in case it is waiting to be processed by ResourceEvent's

     * internal thread.

     *

     * This method has to be called before deleting the TimedEventImpl object.

     * This method cancels any operation of the timer.

     * Then it avoids the situation of the execution thread calling the event handler when it was previously removed.

     * @param event TimedEventImpl object that will be deleted and we have to be sure all its operations are cancelled.

     */

    void unregister_timer(

            TimedEventImpl* event);

    /*!

     * @brief This method notifies to ResourceEvent that the TimedEventImpl object has operations to be scheduled.

     *

     * These operations can be the cancellation of the timer or starting another async_wait.

     * @param event TimedEventImpl object that has operations to be scheduled.

     */

    void notify(

            TimedEventImpl* event);

    /*!

     * @brief This method notifies to ResourceEvent that the TimedEventImpl object has operations to be scheduled.

     *

     * These operations can be the cancellation of the timer or starting another async_wait.

     * @note Non-blocking call version of the method.

     * @param event TimedEventImpl object that has operations to be scheduled.

     * @param timeout Maximum blocking time of the method.

     */

    void notify(

            TimedEventImpl* event,

            const std::chrono::steady_clock::time_point& timeout);

private:

    //! Warns the internal thread can stop.

    std::atomic<bool> stop_{ false };

    //! Protects internal data.

    TimedMutex mutex_;

    //! Used to warn about changes on allow_vector_manipulation_.

    TimedConditionVariable cv_manipulation_;

    //! Flag used to allow a thread to manipulate the timer collections when the execution thread is not using them.

    bool allow_vector_manipulation_ = true;

    //! Used to warn there are new TimedEventImpl objects to be processed.

    TimedConditionVariable cv_;

    //! The total number of created timers.

    size_t timers_count_ = 0;

    //! Collection of events pending update action.

    std::vector<TimedEventImpl*> pending_timers_;

    //! Collection of registered events waiting completion.

    std::vector<TimedEventImpl*> active_timers_;

    //! Prevents iterator invalidation when active_timers are manipulated inside loops

    std::atomic<bool> skip_checking_active_timers_;

    //! Current time as seen by the execution thread.

    std::chrono::steady_clock::time_point current_time_;

    //! Execution thread.

    std::unique_ptr<eprosima::thread> thread_;

    /*!

     * @brief Registers a new TimedEventImpl object in the internal queue to be processed.

     * Non thread safe.

     * @param event Event to be added in the queue.

     * @return True value if the insertion was successful. In other case, it return False.

     */

    bool register_timer_nts(

            TimedEventImpl* event);

    //! Method called by the internal thread.

    void event_service();

    //! Sorts waiting timers in ascending order of trigger time.

    void sort_timers();

    //! Updates internal register of current time.

    void update_current_time();

    //! Method called by the internal thread to process due actions.

    void do_timer_actions();

    //! Ensures internal collections can accommodate current total number of timers.

    void resize_collections()

    {

        pending_timers_.reserve(timers_count_);

        active_timers_.reserve(timers_count_);

    }

};

} /* namespace rtps */

} /* namespace fastdds */

} /* namespace eprosima */

#endif //DOXYGEN_SHOULD_SKIP_THIS_PUBLIC

#endif //FASTDDS_RTPS_RESOURCES__RESOURCEEVENT_H