/*
 *  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

/// \file
/// Implementation of the Diligent::RenderPassBase template class

#include <vector>
#include <utility>

#include "RenderPass.h"
#include "DeviceObjectBase.hpp"
#include "RenderDeviceBase.hpp"

namespace Diligent
{

void ValidateRenderPassDesc(const RenderPassDesc& Desc) noexcept(false);

template <typename RenderDeviceImplType>
void _CorrectAttachmentState(RESOURCE_STATE& State) {}

template <>
inline void _CorrectAttachmentState<class RenderDeviceVkImpl>(RESOURCE_STATE& State)
{
    if (State == RESOURCE_STATE_RESOLVE_DEST)
    {
        // In Vulkan resolve attachments must be in VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL state.
        // It is important to correct the state because outside of render pass RESOURCE_STATE_RESOLVE_DEST maps
        // to VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL.
        State = RESOURCE_STATE_RENDER_TARGET;
    }
}

/// Template class implementing base functionality of the render pass object.

/// \tparam EngineImplTraits - Engine implementation type traits.
template <typename EngineImplTraits>
class RenderPassBase : public DeviceObjectBase<typename EngineImplTraits::RenderPassInterface, typename EngineImplTraits::RenderDeviceImplType, RenderPassDesc>
{
public:
    // Base interface this class inherits (e.g. IRenderPassVk)
    using BaseInterface = typename EngineImplTraits::RenderPassInterface;

    // Render device implementation type (RenderDeviceD3D12Impl, RenderDeviceVkImpl, etc.).
    using RenderDeviceImplType = typename EngineImplTraits::RenderDeviceImplType;

    using TDeviceObjectBase = DeviceObjectBase<BaseInterface, RenderDeviceImplType, RenderPassDesc>;

    /// \param pRefCounters      - Reference counters object that controls the lifetime of this render pass.
    /// \param pDevice           - Pointer to the device.
    /// \param Desc              - Render pass description.
    /// \param bIsDeviceInternal - Flag indicating if the RenderPass is an internal device object and
    ///							   must not keep a strong reference to the device.
    RenderPassBase(IReferenceCounters*   pRefCounters,
                   RenderDeviceImplType* pDevice,
                   const RenderPassDesc& Desc,
                   bool                  bIsDeviceInternal = false) :
        TDeviceObjectBase{pRefCounters, pDevice, Desc, bIsDeviceInternal}
    {
        ValidateRenderPassDesc(this->m_Desc);

        if (Desc.AttachmentCount != 0)
        {
            auto* pAttachments =
                ALLOCATE(GetRawAllocator(), "Memory for RenderPassAttachmentDesc array", RenderPassAttachmentDesc, Desc.AttachmentCount);
            this->m_Desc.pAttachments = pAttachments;
            for (Uint32 i = 0; i < Desc.AttachmentCount; ++i)
            {
                pAttachments[i] = Desc.pAttachments[i];
                _CorrectAttachmentState<RenderDeviceImplType>(pAttachments[i].FinalState);
            }
        }

        Uint32 TotalAttachmentReferencesCount = 0;
        Uint32 TotalPreserveAttachmentsCount  = 0;
        CountSubpassAttachmentReferences(Desc, TotalAttachmentReferencesCount, TotalPreserveAttachmentsCount);
        if (TotalAttachmentReferencesCount != 0)
        {
            m_pAttachmentReferences = ALLOCATE(GetRawAllocator(), "Memory for subpass attachment references array", AttachmentReference, TotalAttachmentReferencesCount);
        }
        if (TotalPreserveAttachmentsCount != 0)
        {
            m_pPreserveAttachments = ALLOCATE(GetRawAllocator(), "Memory for subpass preserve attachments array", Uint32, TotalPreserveAttachmentsCount);
        }

        m_AttachmentStates.resize(Desc.AttachmentCount * Desc.SubpassCount);
        m_AttachmentFirstLastUse.resize(Desc.AttachmentCount, std::pair<Uint32, Uint32>{ATTACHMENT_UNUSED, 0});

        auto* pCurrAttachmentRef      = m_pAttachmentReferences;
        auto* pCurrPreserveAttachment = m_pPreserveAttachments;
        VERIFY(Desc.SubpassCount != 0, "Render pass must have at least one subpass");
        auto* pSubpasses =
            ALLOCATE(GetRawAllocator(), "Memory for SubpassDesc array", SubpassDesc, Desc.SubpassCount);
        this->m_Desc.pSubpasses = pSubpasses;
        for (Uint32 subpass = 0; subpass < Desc.SubpassCount; ++subpass)
        {
            for (Uint32 att = 0; att < Desc.AttachmentCount; ++att)
            {
                SetAttachmentState(subpass, att, subpass > 0 ? GetAttachmentState(subpass - 1, att) : Desc.pAttachments[subpass].InitialState);
            }

            const auto& SrcSubpass = Desc.pSubpasses[subpass];
            auto&       DstSubpass = pSubpasses[subpass];

            auto UpdateAttachmentStateAndFirstUseSubpass = [this, subpass](const AttachmentReference& AttRef) //
            {
                if (AttRef.AttachmentIndex != ATTACHMENT_UNUSED)
                {
                    SetAttachmentState(subpass, AttRef.AttachmentIndex, AttRef.State);
                    auto& FirstLastUse = m_AttachmentFirstLastUse[AttRef.AttachmentIndex];
                    if (FirstLastUse.first == ATTACHMENT_UNUSED)
                        FirstLastUse.first = subpass;
                    FirstLastUse.second = subpass;
                }
            };

            DstSubpass = SrcSubpass;
            if (SrcSubpass.InputAttachmentCount != 0)
            {
                DstSubpass.pInputAttachments = pCurrAttachmentRef;
                for (Uint32 input_attachment = 0; input_attachment < SrcSubpass.InputAttachmentCount; ++input_attachment, ++pCurrAttachmentRef)
                {
                    *pCurrAttachmentRef = SrcSubpass.pInputAttachments[input_attachment];
                    UpdateAttachmentStateAndFirstUseSubpass(*pCurrAttachmentRef);
                }
            }
            else
                DstSubpass.pInputAttachments = nullptr;

            if (SrcSubpass.RenderTargetAttachmentCount != 0)
            {
                DstSubpass.pRenderTargetAttachments = pCurrAttachmentRef;
                for (Uint32 rt_attachment = 0; rt_attachment < SrcSubpass.RenderTargetAttachmentCount; ++rt_attachment, ++pCurrAttachmentRef)
                {
                    *pCurrAttachmentRef = SrcSubpass.pRenderTargetAttachments[rt_attachment];
                    UpdateAttachmentStateAndFirstUseSubpass(*pCurrAttachmentRef);
                }

                if (DstSubpass.pResolveAttachments)
                {
                    DstSubpass.pResolveAttachments = pCurrAttachmentRef;
                    for (Uint32 rslv_attachment = 0; rslv_attachment < SrcSubpass.RenderTargetAttachmentCount; ++rslv_attachment, ++pCurrAttachmentRef)
                    {
                        *pCurrAttachmentRef = SrcSubpass.pResolveAttachments[rslv_attachment];
                        _CorrectAttachmentState<RenderDeviceImplType>(pCurrAttachmentRef->State);
                        UpdateAttachmentStateAndFirstUseSubpass(*pCurrAttachmentRef);
                    }
                }
            }
            else
            {
                DstSubpass.pRenderTargetAttachments = nullptr;
                DstSubpass.pResolveAttachments      = nullptr;
            }

            if (SrcSubpass.pDepthStencilAttachment != nullptr)
            {
                DstSubpass.pDepthStencilAttachment = pCurrAttachmentRef;
                *(pCurrAttachmentRef++)            = *SrcSubpass.pDepthStencilAttachment;
                UpdateAttachmentStateAndFirstUseSubpass(*SrcSubpass.pDepthStencilAttachment);
            }

            if (SrcSubpass.PreserveAttachmentCount != 0)
            {
                DstSubpass.pPreserveAttachments = pCurrPreserveAttachment;
                for (Uint32 prsv_attachment = 0; prsv_attachment < SrcSubpass.PreserveAttachmentCount; ++prsv_attachment)
                    *(pCurrPreserveAttachment++) = SrcSubpass.pPreserveAttachments[prsv_attachment];
            }
            else
                DstSubpass.pPreserveAttachments = nullptr;
        }
        VERIFY_EXPR(pCurrAttachmentRef - m_pAttachmentReferences == static_cast<ptrdiff_t>(TotalAttachmentReferencesCount));
        VERIFY_EXPR(pCurrPreserveAttachment - m_pPreserveAttachments == static_cast<ptrdiff_t>(TotalPreserveAttachmentsCount));

        if (Desc.DependencyCount != 0)
        {
            auto* pDependencies =
                ALLOCATE(GetRawAllocator(), "Memory for SubpassDependencyDesc array", SubpassDependencyDesc, Desc.DependencyCount);
            this->m_Desc.pDependencies = pDependencies;
            for (Uint32 i = 0; i < Desc.DependencyCount; ++i)
            {
                pDependencies[i] = Desc.pDependencies[i];
            }
        }
    }

    ~RenderPassBase()
    {
        auto& RawAllocator = GetRawAllocator();
        if (this->m_Desc.pAttachments != nullptr)
            RawAllocator.Free(const_cast<RenderPassAttachmentDesc*>(this->m_Desc.pAttachments));
        if (this->m_Desc.pSubpasses != nullptr)
            RawAllocator.Free(const_cast<SubpassDesc*>(this->m_Desc.pSubpasses));
        if (this->m_Desc.pDependencies != nullptr)
            RawAllocator.Free(const_cast<SubpassDependencyDesc*>(this->m_Desc.pDependencies));
        if (m_pAttachmentReferences != nullptr)
            RawAllocator.Free(m_pAttachmentReferences);
        if (m_pPreserveAttachments != nullptr)
            RawAllocator.Free(m_pPreserveAttachments);
    }

    IMPLEMENT_QUERY_INTERFACE_IN_PLACE(IID_RenderPass, TDeviceObjectBase)

    RESOURCE_STATE GetAttachmentState(Uint32 Subpass, Uint32 Attachment) const
    {
        VERIFY_EXPR(Attachment < this->m_Desc.AttachmentCount);
        VERIFY_EXPR(Subpass < this->m_Desc.SubpassCount);
        return m_AttachmentStates[this->m_Desc.AttachmentCount * Subpass + Attachment];
    }

    std::pair<Uint32, Uint32> GetAttachmentFirstLastUse(Uint32 Attachment) const
    {
        return m_AttachmentFirstLastUse[Attachment];
    }

protected:
    static void CountSubpassAttachmentReferences(const RenderPassDesc& Desc,
                                                 Uint32&               TotalAttachmentReferencesCount,
                                                 Uint32&               TotalPreserveAttachmentsCount)
    {
        TotalAttachmentReferencesCount = 0;
        TotalPreserveAttachmentsCount  = 0;
        for (Uint32 i = 0; i < Desc.SubpassCount; ++i)
        {
            const auto& Subpass = Desc.pSubpasses[i];
            TotalAttachmentReferencesCount += Subpass.InputAttachmentCount;
            TotalAttachmentReferencesCount += Subpass.RenderTargetAttachmentCount;
            if (Subpass.pResolveAttachments != nullptr)
                TotalAttachmentReferencesCount += Subpass.RenderTargetAttachmentCount;
            if (Subpass.pDepthStencilAttachment != nullptr)
                TotalAttachmentReferencesCount += 1;
            TotalPreserveAttachmentsCount += Subpass.PreserveAttachmentCount;
        }
    }

private:
    void SetAttachmentState(Uint32 Subpass, Uint32 Attachment, RESOURCE_STATE State)
    {
        VERIFY_EXPR(Attachment < this->m_Desc.AttachmentCount);
        VERIFY_EXPR(Subpass < this->m_Desc.SubpassCount);
        m_AttachmentStates[this->m_Desc.AttachmentCount * Subpass + Attachment] = State;
    }

    AttachmentReference* m_pAttachmentReferences = nullptr;
    Uint32*              m_pPreserveAttachments  = nullptr;

    // Attachment states during each subpass
    std::vector<RESOURCE_STATE> m_AttachmentStates;

    // The index of the subpass where the attachment is first used
    std::vector<std::pair<Uint32, Uint32>> m_AttachmentFirstLastUse;
};

} // namespace Diligent