/*
 *  Copyright 2019-2021 Diligent Graphics LLC
 *  Copyright 2015-2019 Egor Yusov
 *  
 *  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.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#pragma once

#include <vector>
#include <deque>

#include "../../GraphicsEngine/interface/RenderDevice.h"
#include "../../GraphicsEngine/interface/DeviceContext.h"
#include "../../GraphicsEngine/interface/Query.h"
#include "../../../Common/interface/RefCntAutoPtr.hpp"

namespace Diligent
{

/// Helper class to manage duration queries.
/// One DurationQueryHelper instance must be used once per frame.
class DurationQueryHelper
{
public:
    DurationQueryHelper(IRenderDevice* pDevice,
                        Uint32         NumQueriesToReserve,
                        Uint32         ExpectedQueryLimit = 5);

    // clang-format off
    DurationQueryHelper           (const DurationQueryHelper&) = delete;
    DurationQueryHelper& operator=(const DurationQueryHelper&) = delete;
    DurationQueryHelper           (DurationQueryHelper&&)      = default;
    DurationQueryHelper& operator=(DurationQueryHelper&&)      = delete;
    // clang-format on


    /// Begins a query.

    /// \param [in] pCtx - Context to record begin query command
    ///
    /// \remarks    There must be exaclty one matching Begin() for every End() call, otherwise
    ///             the behavior is undefined.
    void Begin(IDeviceContext* pCtx);


    /// Ends a query and returns the duration, in seconds, if it is available.

    /// \param [in]  pCtx     - Context to record end query command.
    /// \param [out] Duration - Variable where duration will be written to.
    /// \return                 true if the data from the oldest query is available, and false otherwise.
    ///
    /// \remarks    There must be exaclty one matching End() for every Begin() call, otherwise
    ///             the behavior is undefined.
    bool End(IDeviceContext* pCtx, double& Duration);

private:
    RefCntAutoPtr<IRenderDevice> m_pDevice;

    const Uint32 m_ExpectedQueryLimit;

    struct DurationQuery
    {
        DurationQuery(IRenderDevice* pDevice);

        // clang-format off
        DurationQuery           (const DurationQuery&) = delete;
        DurationQuery& operator=(const DurationQuery&) = delete;
        DurationQuery           (DurationQuery&&)      = default;
        DurationQuery& operator=(DurationQuery&&)      = default;
        // clang-format on

        RefCntAutoPtr<IQuery> StartTimestamp;
        RefCntAutoPtr<IQuery> EndTimestamp;
    };
    void InitDurationQuery(DurationQuery& query);


    std::deque<DurationQuery>  m_PendingQueries;
    std::vector<DurationQuery> m_AvailableQueries;
};

} // namespace Diligent