#include "D3D12WindowRenderLoop.h"

namespace XCEngine::UI::Editor::Host {

D3D12WindowRenderLoopAttachResult D3D12WindowRenderLoop::Attach(
    D3D12UiRenderer& uiRenderer,
    D3D12WindowRenderer& windowRenderer) {
    m_uiRenderer = &uiRenderer;
    m_windowRenderer = &windowRenderer;

    D3D12WindowRenderLoopAttachResult result = {};
    result.hasViewportSurfacePresentation =
        m_windowRenderer->GetSwapChain() != nullptr &&
        m_windowRenderer->GetRHIDevice() != nullptr;
    if (!result.hasViewportSurfacePresentation) {
        result.warning = "window render loop attach requires an initialized D3D12 window renderer.";
    }
    return result;
}

void D3D12WindowRenderLoop::Detach() {
    m_uiRenderer = nullptr;
    m_windowRenderer = nullptr;
}

D3D12WindowRenderLoopFrameContext D3D12WindowRenderLoop::BeginFrame() const {
    D3D12WindowRenderLoopFrameContext context = {};
    if (!HasViewportSurfacePresentation()) {
        return context;
    }

    if (!m_windowRenderer->BeginFrame()) {
        const std::string& frameError = m_windowRenderer->GetLastError();
        context.warning = frameError.empty()
            ? "d3d12 frame begin failed"
            : "d3d12 frame begin failed: " + frameError;
        return context;
    }

    context.canRenderViewports = true;
    context.renderContext = m_windowRenderer->GetRenderContext();
    return context;
}

D3D12WindowRenderLoopResizeResult D3D12WindowRenderLoop::ApplyResize(UINT width, UINT height) {
    D3D12WindowRenderLoopResizeResult result = {};
    if (m_uiRenderer == nullptr || m_windowRenderer == nullptr) {
        result.windowRendererWarning = "window render loop is detached.";
        return result;
    }

    const bool resizedWindowRenderer =
        m_windowRenderer->Resize(static_cast<int>(width), static_cast<int>(height));
    if (!resizedWindowRenderer || !m_windowRenderer->GetLastError().empty()) {
        const std::string& resizeError = m_windowRenderer->GetLastError();
        result.windowRendererWarning = resizeError.empty()
            ? "window renderer resize warning."
            : "window renderer resize warning: " + resizeError;
    }

    result.hasViewportSurfacePresentation =
        resizedWindowRenderer &&
        m_windowRenderer->GetSwapChain() != nullptr &&
        m_windowRenderer->GetCurrentRenderSurface() != nullptr;
    return result;
}

D3D12WindowRenderLoopPresentResult D3D12WindowRenderLoop::Present(
    const ::XCEngine::UI::UIDrawData& drawData,
    const std::filesystem::path* captureOutputPath) {
    D3D12WindowRenderLoopPresentResult result = {};
    if (m_uiRenderer == nullptr) {
        result.warning = "window render loop has no ui renderer.";
        return result;
    }

    if (!HasViewportSurfacePresentation()) {
        result.warning = "window render loop has no active D3D12 presentation path.";
        return result;
    }

    if (!m_windowRenderer->PrepareCurrentBackBufferForUiRender()) {
        const std::string& error = m_windowRenderer->GetLastError();
        result.warning = error.empty()
            ? "failed to prepare the current back buffer for UI rendering."
            : error;
        return result;
    }

    const ::XCEngine::Rendering::RenderContext renderContext =
        m_windowRenderer->GetRenderContext();
    const ::XCEngine::Rendering::RenderSurface* surface =
        m_windowRenderer->GetCurrentRenderSurface();
    if (surface == nullptr) {
        result.warning = "window render loop could not resolve the current back buffer surface.";
        return result;
    }

    if (!m_uiRenderer->Render(drawData, renderContext, *surface)) {
        const std::string& error = m_uiRenderer->GetLastError();
        result.warning = error.empty()
            ? "d3d12 ui renderer failed to render the current frame."
            : error;
        return result;
    }

    if (!m_windowRenderer->FinalizeCurrentBackBufferForPresent()) {
        const std::string& error = m_windowRenderer->GetLastError();
        result.warning = error.empty()
            ? "failed to finalize the current back buffer for present."
            : error;
        return result;
    }

    if (!m_windowRenderer->SubmitFrame()) {
        const std::string& error = m_windowRenderer->GetLastError();
        result.warning = error.empty()
            ? "failed to submit the current D3D12 frame."
            : error;
        return result;
    }

    if (captureOutputPath != nullptr) {
        std::string captureError = {};
        if (!m_windowRenderer->CaptureCurrentBackBufferToPng(*captureOutputPath, captureError)) {
            result.captureError = captureError.empty()
                ? "failed to capture the current D3D12 back buffer."
                : std::move(captureError);
        } else {
            result.captureSucceeded = true;
        }
    }

    const bool presented = m_windowRenderer->PresentFrame();
    const std::string presentError = m_windowRenderer->GetLastError();

    if (!m_windowRenderer->SignalFrameCompletion()) {
        const std::string& error = m_windowRenderer->GetLastError();
        result.warning = error.empty()
            ? "failed to signal current frame completion."
            : error;
        return result;
    }

    if (!presented) {
        result.warning = presentError.empty()
            ? "failed to present the swap chain."
            : presentError;
        return result;
    }

    result.framePresented = true;
    return result;
}

bool D3D12WindowRenderLoop::HasViewportSurfacePresentation() const {
    return m_uiRenderer != nullptr &&
        m_windowRenderer != nullptr &&
        m_windowRenderer->GetSwapChain() != nullptr &&
        m_windowRenderer->GetCurrentRenderSurface() != nullptr;
}

} // namespace XCEngine::UI::Editor::Host