#include "XCUIDemoPanel.h"

#include "XCUIBackend/ImGuiXCUIHostedPreviewPresenter.h"
#include "XCUIBackend/ImGuiXCUIPanelCanvasHost.h"
#include "XCUIBackend/ImGuiXCUIInputAdapter.h"

#include <XCEngine/UI/Types.h>

#include <imgui.h>

#include <algorithm>
#include <chrono>
#include <cstdint>
#include <string>
#include <utility>

namespace XCEngine {
namespace NewEditor {

namespace {

constexpr float kCanvasHudHeight = 82.0f;
constexpr float kCanvasHudPadding = 10.0f;
constexpr char kPreviewDebugName[] = "XCUI Demo";
constexpr char kPreviewDebugSource[] = "new_editor.panels.xcui_demo";

bool ContainsPoint(const UI::UIRect& rect, const UI::UIPoint& point) {
    return point.x >= rect.x &&
        point.y >= rect.y &&
        point.x <= rect.x + rect.width &&
        point.y <= rect.y + rect.height;
}

void DrawRectOverlay(
    ::XCEngine::Editor::XCUIBackend::IXCUIPanelCanvasHost& canvasHost,
    ::XCEngine::Editor::XCUIBackend::XCUIDemoRuntime& runtime,
    const std::string& elementId,
    const UI::UIColor& color,
    const char* label) {
    if (elementId.empty()) {
        return;
    }

    UI::UIRect rect = {};
    if (!runtime.TryGetElementRect(elementId, rect)) {
        return;
    }

    canvasHost.DrawOutlineRect(rect, color, 2.0f, 6.0f);
    if (label != nullptr && label[0] != '\0') {
        canvasHost.DrawText(
            UI::UIPoint(rect.x + 4.0f, rect.y + 4.0f),
            label,
            color);
    }
}

const char* GetPreviewPathLabel(bool nativeHostedPreview) {
    return nativeHostedPreview ? "native queued offscreen surface" : "legacy imgui transition";
}

const char* GetPreviewStateLabel(
    bool nativeHostedPreview,
    const ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewStats& previewStats,
    bool hasHostedSurfaceDescriptor,
    bool showHostedSurfaceImage) {
    if (nativeHostedPreview) {
        if (showHostedSurfaceImage) {
            return "live";
        }
        if (previewStats.queuedToNativePass || hasHostedSurfaceDescriptor) {
            return "warming";
        }
        return "awaiting submit";
    }

    return previewStats.presented ? "live" : "idle";
}

} // namespace

XCUIDemoPanel::XCUIDemoPanel(::XCEngine::Editor::XCUIBackend::XCUIWin32InputSource* inputSource)
    : XCUIDemoPanel(inputSource, ::XCEngine::Editor::XCUIBackend::CreateImGuiXCUIHostedPreviewPresenter()) {}

XCUIDemoPanel::XCUIDemoPanel(
    ::XCEngine::Editor::XCUIBackend::XCUIWin32InputSource* inputSource,
    std::unique_ptr<::XCEngine::Editor::XCUIBackend::IXCUIHostedPreviewPresenter> previewPresenter)
    : Panel("XCUI Demo")
    , m_inputSource(inputSource)
    , m_previewPresenter(std::move(previewPresenter))
    , m_canvasHost(::XCEngine::Editor::XCUIBackend::CreateImGuiXCUIPanelCanvasHost()) {
    if (m_previewPresenter == nullptr) {
        m_previewPresenter = ::XCEngine::Editor::XCUIBackend::CreateImGuiXCUIHostedPreviewPresenter();
    }
    m_lastReloadSucceeded = m_runtime.ReloadDocuments();
}

void XCUIDemoPanel::SetHostedPreviewEnabled(bool enabled) {
    m_hostedPreviewEnabled = enabled;
    if (!m_hostedPreviewEnabled) {
        m_lastPreviewStats = {};
    }
}

const ::XCEngine::Editor::XCUIBackend::XCUIDemoFrameResult& XCUIDemoPanel::GetFrameResult() const {
    return m_runtime.GetFrameResult();
}

const ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewStats& XCUIDemoPanel::GetLastPreviewStats() const {
    return m_lastPreviewStats;
}

void XCUIDemoPanel::SetHostedPreviewPresenter(
    std::unique_ptr<::XCEngine::Editor::XCUIBackend::IXCUIHostedPreviewPresenter> previewPresenter) {
    m_previewPresenter = std::move(previewPresenter);
    if (m_previewPresenter == nullptr) {
        m_previewPresenter = ::XCEngine::Editor::XCUIBackend::CreateImGuiXCUIHostedPreviewPresenter();
    }
    m_lastPreviewStats = {};
}

void XCUIDemoPanel::SetCanvasHost(
    std::unique_ptr<::XCEngine::Editor::XCUIBackend::IXCUIPanelCanvasHost> canvasHost) {
    m_canvasHost = std::move(canvasHost);
    if (m_canvasHost == nullptr) {
        m_canvasHost = ::XCEngine::Editor::XCUIBackend::CreateImGuiXCUIPanelCanvasHost();
    }
}

bool XCUIDemoPanel::IsUsingNativeHostedPreview() const {
    return m_previewPresenter != nullptr && m_previewPresenter->IsNativeQueued();
}

void XCUIDemoPanel::Render() {
    ImGui::SetNextWindowSize(ImVec2(1040.0f, 720.0f), ImGuiCond_Appearing);
    ImGui::SetNextWindowDockID(ImGui::GetID("XCNewEditorDockSpace"), ImGuiCond_Appearing);

    bool open = true;
    if (!ImGui::Begin(GetName().c_str(), &open)) {
        ImGui::End();
        if (!open) {
            SetVisible(false);
        }
        return;
    }

    if (ImGui::Button("Reload Documents")) {
        m_lastReloadSucceeded = m_runtime.ReloadDocuments();
    }
    ImGui::SameLine();
    ImGui::Checkbox("Canvas HUD", &m_showCanvasHud);
    ImGui::SameLine();
    ImGui::Checkbox("Debug Rects", &m_showDebugRects);
    ImGui::SameLine();
    ImGui::TextUnformatted(m_lastReloadSucceeded ? "Reload: OK" : "Reload: Failed");
    ImGui::Separator();

    const float diagnosticsHeight = 232.0f;
    const ImVec2 hostRegion = ImGui::GetContentRegionAvail();
    const float canvasHeight = (std::max)(140.0f, hostRegion.y - diagnosticsHeight);

    if (m_canvasHost == nullptr) {
        m_canvasHost = ::XCEngine::Editor::XCUIBackend::CreateImGuiXCUIPanelCanvasHost();
    }

    const bool nativeHostedPreview = IsUsingNativeHostedPreview();
    ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewSurfaceDescriptor hostedSurfaceDescriptor = {};
    const bool hasHostedSurfaceDescriptor =
        nativeHostedPreview &&
        m_previewPresenter != nullptr &&
        m_previewPresenter->TryGetSurfaceDescriptor(kPreviewDebugName, hostedSurfaceDescriptor);
    ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewSurfaceImage hostedSurfaceImage = {};
    const bool showHostedSurfaceImage =
        nativeHostedPreview &&
        m_previewPresenter != nullptr &&
        m_previewPresenter->TryGetSurfaceImage(kPreviewDebugName, hostedSurfaceImage);
    const char* const previewPathLabel = GetPreviewPathLabel(nativeHostedPreview);
    const float topInset = m_showCanvasHud ? (kCanvasHudHeight + kCanvasHudPadding) : 0.0f;
    ::XCEngine::Editor::XCUIBackend::XCUIPanelCanvasRequest canvasRequest = {};
    canvasRequest.childId = "XCUIDemoCanvasHost";
    canvasRequest.height = canvasHeight;
    canvasRequest.topInset = topInset;
    canvasRequest.showSurfaceImage = showHostedSurfaceImage;
    canvasRequest.surfaceImage = hostedSurfaceImage;
    canvasRequest.placeholderTitle =
        nativeHostedPreview ? "Native XCUI preview pending" : "Legacy XCUI canvas host";
    canvasRequest.placeholderSubtitle =
        nativeHostedPreview
        ? "Waiting for native queued render output to publish back into the sandbox panel."
        : "Legacy ImGui transition path stays active until native offscreen preview is enabled.";
    const ::XCEngine::Editor::XCUIBackend::XCUIPanelCanvasSession canvasSession =
        m_canvasHost->BeginCanvas(canvasRequest);
    const UI::UIRect canvasRect = canvasSession.canvasRect;
    const bool validCanvas = canvasSession.validCanvas;

    ::XCEngine::Editor::XCUIBackend::XCUIDemoInputState input = {};
    ::XCEngine::Editor::XCUIBackend::XCUIInputBridgeCaptureOptions bridgeOptions = {};
    bridgeOptions.timestampNanoseconds = static_cast<std::uint64_t>(
        std::chrono::duration_cast<std::chrono::nanoseconds>(
            std::chrono::steady_clock::now().time_since_epoch())
            .count());

    ::XCEngine::Editor::XCUIBackend::XCUIInputBridgeFrameSnapshot snapshot = {};
    if (m_inputSource != nullptr) {
        bridgeOptions.hasPointerInsideOverride = true;
        bridgeOptions.windowFocused = canvasSession.windowFocused;
        const UI::UIPoint pointerPosition = m_inputSource->GetPointerPosition();
        bridgeOptions.pointerInsideOverride = validCanvas && ContainsPoint(canvasRect, pointerPosition);
        snapshot = m_inputSource->CaptureSnapshot(bridgeOptions);
    } else {
        bridgeOptions.hasPointerInsideOverride = true;
        bridgeOptions.pointerInsideOverride = validCanvas && canvasSession.hovered;
        bridgeOptions.windowFocused = canvasSession.windowFocused;
        snapshot = ::XCEngine::Editor::XCUIBackend::ImGuiXCUIInputAdapter::CaptureSnapshot(
            ImGui::GetIO(),
            bridgeOptions);
        snapshot.pointerPosition = canvasSession.pointerPosition;
    }

    if (!m_inputBridge.HasBaseline()) {
        m_inputBridge.Prime(snapshot);
    }
    const ::XCEngine::Editor::XCUIBackend::XCUIInputBridgeFrameDelta frameDelta =
        m_inputBridge.Translate(snapshot);

    input.canvasRect = canvasRect;
    input.pointerPosition = snapshot.pointerPosition;
    input.pointerInside = snapshot.pointerInside;
    input.pointerPressed = frameDelta.pointer.pressed[0];
    input.pointerReleased = frameDelta.pointer.released[0];
    input.pointerDown = snapshot.pointerButtonsDown[0];
    input.windowFocused = snapshot.windowFocused;
    input.shortcutPressed = false;
    input.wantCaptureMouse = snapshot.wantCaptureMouse;
    input.wantCaptureKeyboard = snapshot.wantCaptureKeyboard;
    input.wantTextInput = snapshot.wantTextInput;
    input.events = frameDelta.events;

    const ::XCEngine::Editor::XCUIBackend::XCUIDemoFrameResult& frame = m_runtime.Update(input);

    if (m_hostedPreviewEnabled && m_previewPresenter != nullptr) {
        ::XCEngine::Editor::XCUIBackend::XCUIHostedPreviewFrame previewFrame = {};
        previewFrame.drawData = &frame.drawData;
        previewFrame.canvasRect = canvasRect;
        previewFrame.logicalSize = UI::UISize(canvasRect.width, canvasRect.height);
        previewFrame.debugName = kPreviewDebugName;
        previewFrame.debugSource = kPreviewDebugSource;
        m_previewPresenter->Present(previewFrame);
        m_lastPreviewStats = m_previewPresenter->GetLastStats();
    } else {
        m_lastPreviewStats = {};
    }

    const ::XCEngine::Editor::XCUIBackend::XCUIDemoFrameStats& stats = frame.stats;
    const char* const previewStateLabel = GetPreviewStateLabel(
        nativeHostedPreview,
        m_lastPreviewStats,
        hasHostedSurfaceDescriptor,
        showHostedSurfaceImage);
    if (m_showCanvasHud) {
        const float hudWidth = (std::min)(canvasSession.hostRect.width - 16.0f, 430.0f);
        const UI::UIRect hudRect(
            canvasSession.hostRect.x + 8.0f,
            canvasSession.hostRect.y + 8.0f,
            (std::max)(0.0f, hudWidth),
            kCanvasHudHeight - 8.0f);
        m_canvasHost->DrawFilledRect(
            hudRect,
            UI::UIColor(16.0f / 255.0f, 22.0f / 255.0f, 30.0f / 255.0f, 220.0f / 255.0f),
            8.0f);
        m_canvasHost->DrawOutlineRect(
            hudRect,
            UI::UIColor(52.0f / 255.0f, 72.0f / 255.0f, 96.0f / 255.0f, 1.0f),
            1.0f,
            8.0f);

        const UI::UIPoint lineOrigin(hudRect.x + 10.0f, hudRect.y + 8.0f);
        const UI::UIColor textColor(191.0f / 255.0f, 205.0f / 255.0f, 224.0f / 255.0f, 1.0f);
        m_canvasHost->DrawText(lineOrigin, "XCUI Runtime", UI::UIColor(1.0f, 1.0f, 1.0f, 1.0f));

        std::string previewLine = std::string(previewPathLabel) + " | " + previewStateLabel;
        std::string treeLine =
            "Tree " + std::to_string(static_cast<unsigned long long>(stats.treeGeneration)) +
            " | Elements " + std::to_string(stats.elementCount) +
            " | Commands " + std::to_string(stats.commandCount);
        std::string flushLine =
            "Submit " + std::to_string(m_lastPreviewStats.submittedDrawListCount) +
            "/" + std::to_string(m_lastPreviewStats.submittedCommandCount) +
            " | Flush " + std::to_string(m_lastPreviewStats.flushedDrawListCount) +
            "/" + std::to_string(m_lastPreviewStats.flushedCommandCount);

        m_canvasHost->DrawText(UI::UIPoint(lineOrigin.x, lineOrigin.y + 18.0f), previewLine, textColor);
        m_canvasHost->DrawText(UI::UIPoint(lineOrigin.x, lineOrigin.y + 36.0f), stats.statusMessage, textColor);
        m_canvasHost->DrawText(UI::UIPoint(lineOrigin.x, lineOrigin.y + 54.0f), treeLine, textColor);
        m_canvasHost->DrawText(UI::UIPoint(lineOrigin.x + 210.0f, lineOrigin.y + 54.0f), flushLine, textColor);
    }

    if (m_showDebugRects && validCanvas && (!nativeHostedPreview || showHostedSurfaceImage)) {
        DrawRectOverlay(
            *m_canvasHost,
            m_runtime,
            stats.hoveredElementId,
            UI::UIColor(1.0f, 195.0f / 255.0f, 64.0f / 255.0f, 1.0f),
            "hover");
        DrawRectOverlay(
            *m_canvasHost,
            m_runtime,
            stats.focusedElementId,
            UI::UIColor(64.0f / 255.0f, 214.0f / 255.0f, 1.0f, 1.0f),
            "focus");
        DrawRectOverlay(
            *m_canvasHost,
            m_runtime,
            "toggleAccent",
            UI::UIColor(150.0f / 255.0f, 1.0f, 150.0f / 255.0f, 160.0f / 255.0f),
            "toggle");
    }
    m_canvasHost->EndCanvas();

    ImGui::Separator();
    ImGui::BeginChild("XCUIDemoDiagnostics", ImVec2(0.0f, 0.0f), false, ImGuiWindowFlags_NoScrollbar);
    ImGui::SeparatorText("Preview");
    ImGui::Text("Path: %s | state: %s", previewPathLabel, previewStateLabel);
    ImGui::Text(
        "Presenter: presented %s | submit->native %s",
        m_lastPreviewStats.presented ? "yes" : "no",
        m_lastPreviewStats.queuedToNativePass ? "yes" : "no");
    ImGui::Text(
        "Submitted: %zu lists / %zu cmds | Flushed: %zu lists / %zu cmds",
        m_lastPreviewStats.submittedDrawListCount,
        m_lastPreviewStats.submittedCommandCount,
        m_lastPreviewStats.flushedDrawListCount,
        m_lastPreviewStats.flushedCommandCount);
    ImGui::TextWrapped(
        "Source: %s",
        hasHostedSurfaceDescriptor && !hostedSurfaceDescriptor.debugSource.empty()
            ? hostedSurfaceDescriptor.debugSource.c_str()
            : kPreviewDebugSource);
    if (nativeHostedPreview) {
        ImGui::Text(
            "Surface descriptor: %s | image published: %s | queued frame index: %zu",
            hasHostedSurfaceDescriptor ? "yes" : "no",
            showHostedSurfaceImage ? "yes" : "no",
            hasHostedSurfaceDescriptor ? hostedSurfaceDescriptor.queuedFrameIndex : 0u);
        if (hasHostedSurfaceDescriptor) {
            ImGui::Text(
                "Surface: %ux%u | logical: %.0f x %.0f | rendered rect: %.0f, %.0f %.0f x %.0f",
                hostedSurfaceDescriptor.image.surfaceWidth,
                hostedSurfaceDescriptor.image.surfaceHeight,
                hostedSurfaceDescriptor.logicalSize.width,
                hostedSurfaceDescriptor.logicalSize.height,
                hostedSurfaceDescriptor.image.renderedCanvasRect.x,
                hostedSurfaceDescriptor.image.renderedCanvasRect.y,
                hostedSurfaceDescriptor.image.renderedCanvasRect.width,
                hostedSurfaceDescriptor.image.renderedCanvasRect.height);
        } else {
            ImGui::TextDisabled("No native surface descriptor has been published back yet.");
        }
    } else {
        ImGui::TextDisabled("Legacy path renders directly into the panel draw list. No native surface descriptor exists.");
    }

    ImGui::SeparatorText("Runtime");
    ImGui::Text("Status: %s", stats.statusMessage.c_str());
    ImGui::Text(
        "Tree gen: %llu | elements: %zu | dirty roots: %zu",
        static_cast<unsigned long long>(stats.treeGeneration),
        stats.elementCount,
        stats.dirtyRootCount);
    ImGui::Text(
        "Draw lists: %zu | draw cmds: %zu | dependencies: %zu",
        stats.drawListCount,
        stats.commandCount,
        stats.dependencyCount);
    ImGui::Text(
        "Hovered: %s | Focused: %s",
        stats.hoveredElementId.empty() ? "none" : stats.hoveredElementId.c_str(),
        stats.focusedElementId.empty() ? "none" : stats.focusedElementId.c_str());
    ImGui::Text(
        "Last command: %s | Accent: %s",
        stats.lastCommandId.empty() ? "none" : stats.lastCommandId.c_str(),
        stats.accentEnabled ? "on" : "off");
    ImGui::Text("Canvas: %.0f x %.0f", input.canvasRect.width, input.canvasRect.height);

    ImGui::SeparatorText("Input");
    ImGui::Text(
        "Pointer: %.0f, %.0f | inside %s | down %s | pressed %s | released %s",
        input.pointerPosition.x,
        input.pointerPosition.y,
        input.pointerInside ? "yes" : "no",
        input.pointerDown ? "yes" : "no",
        input.pointerPressed ? "yes" : "no",
        input.pointerReleased ? "yes" : "no");
    ImGui::Text(
        "Focus %s | capture mouse %s | capture keyboard %s | text input %s | events %zu",
        input.windowFocused ? "yes" : "no",
        input.wantCaptureMouse ? "yes" : "no",
        input.wantCaptureKeyboard ? "yes" : "no",
        input.wantTextInput ? "yes" : "no",
        input.events.size());
    ImGui::EndChild();

    ImGui::End();

    if (!open) {
        SetVisible(false);
    }
}

} // namespace NewEditor
} // namespace XCEngine