/*
 * Copyright (c) Contributors to the Open 3D Engine Project.
 * For complete copyright and license terms please see the LICENSE at the root of this distribution.
 *
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 */

#include <Atom/RHI/CommandList.h>
#include <Atom/RHI/DispatchRaysItem.h>
#include <Atom/RHI/Factory.h>
#include <Atom/RHI/RHISystemInterface.h>
#include <Atom/RPI.Public/RenderPipeline.h>
#include <Atom/RPI.Public/Scene.h>
#include <Atom/RPI.Public/RPIUtils.h>
#include <Atom/RPI.Public/View.h>
#include <Atom_Feature_Traits_Platform.h>
#include <DiffuseGlobalIllumination/DiffuseProbeGridFeatureProcessor.h>
#include <DiffuseGlobalIllumination/DiffuseProbeGridVisualizationRayTracingPass.h>

namespace AZ
{
    namespace Render
    {
        RPI::Ptr<DiffuseProbeGridVisualizationRayTracingPass> DiffuseProbeGridVisualizationRayTracingPass::Create(const RPI::PassDescriptor& descriptor)
        {
            RPI::Ptr<DiffuseProbeGridVisualizationRayTracingPass> pass = aznew DiffuseProbeGridVisualizationRayTracingPass(descriptor);
            return AZStd::move(pass);
        }

        DiffuseProbeGridVisualizationRayTracingPass::DiffuseProbeGridVisualizationRayTracingPass(const RPI::PassDescriptor& descriptor)
            : RPI::RenderPass(descriptor)
        {
            RHI::Ptr<RHI::Device> device = RHI::RHISystemInterface::Get()->GetDevice();
            if (device->GetFeatures().m_rayTracing == false || !AZ_TRAIT_DIFFUSE_GI_PASSES_SUPPORTED)
            {
                // raytracing or GI is not supported on this platform
                SetEnabled(false);
            }
        }

        void DiffuseProbeGridVisualizationRayTracingPass::CreateRayTracingPipelineState()
        {
            RHI::Ptr<RHI::Device> device = RHI::RHISystemInterface::Get()->GetDevice();

            // load the ray tracing shader
            // Note: the shader may not be available on all platforms
            AZStd::string shaderFilePath = "Shaders/DiffuseGlobalIllumination/DiffuseProbeGridVisualizationRayTracing.azshader";
            m_rayTracingShader = RPI::LoadCriticalShader(shaderFilePath);
            if (m_rayTracingShader == nullptr)
            {
                return;
            }

            auto shaderVariant = m_rayTracingShader->GetVariant(RPI::ShaderAsset::RootShaderVariantStableId);
            RHI::PipelineStateDescriptorForRayTracing rayGenerationShaderDescriptor;
            shaderVariant.ConfigurePipelineState(rayGenerationShaderDescriptor);

            // closest hit shader
            AZStd::string closestHitShaderFilePath = "Shaders/DiffuseGlobalIllumination/DiffuseProbeGridVisualizationRayTracingClosestHit.azshader";
            m_closestHitShader = RPI::LoadCriticalShader(closestHitShaderFilePath);

            auto closestHitShaderVariant = m_closestHitShader->GetVariant(RPI::ShaderAsset::RootShaderVariantStableId);
            RHI::PipelineStateDescriptorForRayTracing closestHitShaderDescriptor;
            closestHitShaderVariant.ConfigurePipelineState(closestHitShaderDescriptor);

            // miss shader
            AZStd::string missShaderFilePath = "Shaders/DiffuseGlobalIllumination/DiffuseProbeGridVisualizationRayTracingMiss.azshader";
            m_missShader = RPI::LoadCriticalShader(missShaderFilePath);

            auto missShaderVariant = m_missShader->GetVariant(RPI::ShaderAsset::RootShaderVariantStableId);
            RHI::PipelineStateDescriptorForRayTracing missShaderDescriptor;
            missShaderVariant.ConfigurePipelineState(missShaderDescriptor);

            // global pipeline state and Srg
            m_globalPipelineState = m_rayTracingShader->AcquirePipelineState(rayGenerationShaderDescriptor);
            AZ_Assert(m_globalPipelineState, "Failed to acquire ray tracing global pipeline state");

            m_globalSrgLayout = m_rayTracingShader->FindShaderResourceGroupLayout(Name{ "RayTracingGlobalSrg" });
            AZ_Assert(m_globalSrgLayout != nullptr, "Failed to find RayTracingGlobalSrg layout for shader [%s]", shaderFilePath.c_str());

            // build the ray tracing pipeline state descriptor
            RHI::RayTracingPipelineStateDescriptor descriptor;
            descriptor.Build()
                ->PipelineState(m_globalPipelineState.get())
                ->MaxPayloadSize(64)
                ->MaxAttributeSize(32)
                ->MaxRecursionDepth(2)
                ->ShaderLibrary(rayGenerationShaderDescriptor)
                    ->RayGenerationShaderName(AZ::Name("RayGen"))
                ->ShaderLibrary(missShaderDescriptor)
                    ->MissShaderName(AZ::Name("Miss"))
                ->ShaderLibrary(closestHitShaderDescriptor)
                    ->ClosestHitShaderName(AZ::Name("ClosestHit"))
                ->HitGroup(AZ::Name("HitGroup"))
                    ->ClosestHitShaderName(AZ::Name("ClosestHit"));

            // create the ray tracing pipeline state object
            m_rayTracingPipelineState = RHI::Factory::Get().CreateRayTracingPipelineState();
            m_rayTracingPipelineState->Init(*device.get(), &descriptor);
        }

        bool DiffuseProbeGridVisualizationRayTracingPass::IsEnabled() const
        {
            if (!RenderPass::IsEnabled())
            {
                return false;
            }

            RPI::Scene* scene = m_pipeline->GetScene();
            if (!scene)
            {
                return false;
            }

            DiffuseProbeGridFeatureProcessor* diffuseProbeGridFeatureProcessor = scene->GetFeatureProcessor<DiffuseProbeGridFeatureProcessor>();
            if (diffuseProbeGridFeatureProcessor)
            {
                for (auto& diffuseProbeGrid : diffuseProbeGridFeatureProcessor->GetVisibleProbeGrids())
                {
                    if (diffuseProbeGrid->GetVisualizationEnabled())
                    {
                        return true;
                    }
                }
            }

            return false;
        }

        void DiffuseProbeGridVisualizationRayTracingPass::FrameBeginInternal(FramePrepareParams params)
        {
            RPI::Scene* scene = m_pipeline->GetScene();
            DiffuseProbeGridFeatureProcessor* diffuseProbeGridFeatureProcessor = scene->GetFeatureProcessor<DiffuseProbeGridFeatureProcessor>();

            if (!m_initialized)
            {
                CreateRayTracingPipelineState();
                m_initialized = true;
            }

            if (!m_rayTracingShaderTable)
            {
                RHI::Ptr<RHI::Device> device = RHI::RHISystemInterface::Get()->GetDevice();
                RHI::RayTracingBufferPools& rayTracingBufferPools = diffuseProbeGridFeatureProcessor->GetVisualizationBufferPools();

                m_rayTracingShaderTable = RHI::Factory::Get().CreateRayTracingShaderTable();
                m_rayTracingShaderTable->Init(*device.get(), rayTracingBufferPools);

                AZStd::shared_ptr<RHI::RayTracingShaderTableDescriptor> descriptor = AZStd::make_shared<RHI::RayTracingShaderTableDescriptor>();

                // build the ray tracing shader table descriptor
                descriptor->Build(AZ::Name("RayTracingShaderTable"), m_rayTracingPipelineState)
                    ->RayGenerationRecord(AZ::Name("RayGen"))
                    ->MissRecord(AZ::Name("Miss"))
                    ->HitGroupRecord(AZ::Name("HitGroup"))
                ;

                m_rayTracingShaderTable->Build(descriptor);
            }

            RenderPass::FrameBeginInternal(params);
        }

        void DiffuseProbeGridVisualizationRayTracingPass::SetupFrameGraphDependencies(RHI::FrameGraphInterface frameGraph)
        {
            RenderPass::SetupFrameGraphDependencies(frameGraph);

            RPI::Scene* scene = m_pipeline->GetScene();
            DiffuseProbeGridFeatureProcessor* diffuseProbeGridFeatureProcessor = scene->GetFeatureProcessor<DiffuseProbeGridFeatureProcessor>();

            for (auto& diffuseProbeGrid : diffuseProbeGridFeatureProcessor->GetVisibleProbeGrids())
            {
                if (!diffuseProbeGrid->GetVisualizationEnabled())
                {
                    continue;
                }

                // TLAS
                {
                    AZ::RHI::AttachmentId tlasAttachmentId = diffuseProbeGrid->GetProbeVisualizationTlasAttachmentId();
                    const RHI::Ptr<RHI::Buffer>& visualizationTlasBuffer = diffuseProbeGrid->GetVisualizationTlas()->GetTlasBuffer();
                    if (visualizationTlasBuffer)
                    {
                        if (!frameGraph.GetAttachmentDatabase().IsAttachmentValid(tlasAttachmentId))
                        {
                            [[maybe_unused]] RHI::ResultCode result = frameGraph.GetAttachmentDatabase().ImportBuffer(tlasAttachmentId, visualizationTlasBuffer);
                            AZ_Assert(result == RHI::ResultCode::Success, "Failed to import ray tracing TLAS buffer with error %d", result);
                        }

                        uint32_t tlasBufferByteCount = aznumeric_cast<uint32_t>(visualizationTlasBuffer->GetDescriptor().m_byteCount);
                        RHI::BufferViewDescriptor tlasBufferViewDescriptor = RHI::BufferViewDescriptor::CreateRaw(0, tlasBufferByteCount);

                        RHI::BufferScopeAttachmentDescriptor desc;
                        desc.m_attachmentId = tlasAttachmentId;
                        desc.m_bufferViewDescriptor = tlasBufferViewDescriptor;
                        desc.m_loadStoreAction.m_loadAction = AZ::RHI::AttachmentLoadAction::Load;

                        frameGraph.UseShaderAttachment(desc, RHI::ScopeAttachmentAccess::ReadWrite);
                    }
                }

                // probe irradiance
                {
                    RHI::ImageScopeAttachmentDescriptor desc;
                    desc.m_attachmentId = diffuseProbeGrid->GetIrradianceImageAttachmentId();
                    desc.m_imageViewDescriptor = diffuseProbeGrid->GetRenderData()->m_probeIrradianceImageViewDescriptor;
                    desc.m_loadStoreAction.m_loadAction = AZ::RHI::AttachmentLoadAction::Load;
                    frameGraph.UseShaderAttachment(desc, RHI::ScopeAttachmentAccess::Read);
                }

                // probe distance
                {
                    RHI::ImageScopeAttachmentDescriptor desc;
                    desc.m_attachmentId = diffuseProbeGrid->GetDistanceImageAttachmentId();
                    desc.m_imageViewDescriptor = diffuseProbeGrid->GetRenderData()->m_probeDistanceImageViewDescriptor;
                    desc.m_loadStoreAction.m_loadAction = AZ::RHI::AttachmentLoadAction::Load;

                    frameGraph.UseShaderAttachment(desc, RHI::ScopeAttachmentAccess::Read);
                }

                // probe data
                {
                    RHI::ImageScopeAttachmentDescriptor desc;
                    desc.m_attachmentId = diffuseProbeGrid->GetProbeDataImageAttachmentId();
                    desc.m_imageViewDescriptor = diffuseProbeGrid->GetRenderData()->m_probeDataImageViewDescriptor;
                    desc.m_loadStoreAction.m_loadAction = AZ::RHI::AttachmentLoadAction::Load;

                    frameGraph.UseShaderAttachment(desc, RHI::ScopeAttachmentAccess::Read);
                }
            }

            // retrieve the visualization image size, this will determine the number of rays to cast
            RPI::Ptr<RPI::PassAttachment> visualizationImageAttachment = m_ownedAttachments[0];
            AZ_Assert(visualizationImageAttachment.get(), "Invalid DiffuseProbeGrid Visualization image");

            m_outputAttachmentSize = visualizationImageAttachment->GetTransientImageDescriptor().m_imageDescriptor.m_size;
        }

        void DiffuseProbeGridVisualizationRayTracingPass::CompileResources([[maybe_unused]] const RHI::FrameGraphCompileContext& context)
        {           
            const RHI::ImageView* outputImageView = context.GetImageView(GetOutputBinding(0).m_attachment->GetAttachmentId());
            AZ_Assert(outputImageView, "Failed to retrieve output ImageView");

            RPI::Scene* scene = m_pipeline->GetScene();
            DiffuseProbeGridFeatureProcessor* diffuseProbeGridFeatureProcessor = scene->GetFeatureProcessor<DiffuseProbeGridFeatureProcessor>();

            for (auto& diffuseProbeGrid : diffuseProbeGridFeatureProcessor->GetVisibleProbeGrids())
            {
                if (!diffuseProbeGrid->GetVisualizationEnabled())
                {
                    continue;
                }

                // the DiffuseProbeGridVisualization Srg must be updated in the Compile phase in order to successfully bind the ReadWrite shader
                // inputs (see line ValidateSetImageView() in ShaderResourceGroupData.cpp)
                diffuseProbeGrid->UpdateVisualizationRayTraceSrg(m_rayTracingShader, m_globalSrgLayout, outputImageView);
                diffuseProbeGrid->GetVisualizationRayTraceSrg()->Compile();
            }
        }
    
        void DiffuseProbeGridVisualizationRayTracingPass::BuildCommandListInternal([[maybe_unused]] const RHI::FrameGraphExecuteContext& context)
        {
            RPI::Scene* scene = m_pipeline->GetScene();
            DiffuseProbeGridFeatureProcessor* diffuseProbeGridFeatureProcessor = scene->GetFeatureProcessor<DiffuseProbeGridFeatureProcessor>();

            const AZStd::vector<RPI::ViewPtr>& views = m_pipeline->GetViews(RPI::PipelineViewTag{ "MainCamera" });
            if (views.empty())
            {
                return;
            }

            for (auto& diffuseProbeGrid : diffuseProbeGridFeatureProcessor->GetVisibleProbeGrids())
            {
                if (!diffuseProbeGrid->GetVisualizationEnabled())
                {
                    continue;
                }

                const RHI::ShaderResourceGroup* shaderResourceGroups[] = {
                    diffuseProbeGrid->GetVisualizationRayTraceSrg()->GetRHIShaderResourceGroup(),
                    views[0]->GetRHIShaderResourceGroup()
                };

                RHI::DispatchRaysItem dispatchRaysItem;
                dispatchRaysItem.m_width = m_outputAttachmentSize.m_width;
                dispatchRaysItem.m_height = m_outputAttachmentSize.m_height;
                dispatchRaysItem.m_depth = 1;
                dispatchRaysItem.m_rayTracingPipelineState = m_rayTracingPipelineState.get();
                dispatchRaysItem.m_rayTracingShaderTable = m_rayTracingShaderTable.get();
                dispatchRaysItem.m_shaderResourceGroupCount = RHI::ArraySize(shaderResourceGroups);
                dispatchRaysItem.m_shaderResourceGroups = shaderResourceGroups;
                dispatchRaysItem.m_globalPipelineState = m_globalPipelineState.get();

                // submit the DispatchRays item
                context.GetCommandList()->Submit(dispatchRaysItem);
            }
        }
    }   // namespace RPI
}   // namespace AZ