#include "XCUIDemoPanel.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 ImU32 kPreviewFrameColor = IM_COL32(54, 72, 94, 255);
constexpr ImU32 kPreviewPlaceholderFill = IM_COL32(18, 24, 32, 255);
constexpr ImU32 kPreviewPlaceholderText = IM_COL32(191, 205, 224, 255);
constexpr ImU32 kPreviewPlaceholderSubtleText = IM_COL32(132, 147, 170, 255);
constexpr char kPreviewDebugName[] = "XCUI Demo";
constexpr char kPreviewDebugSource[] = "new_editor.panels.xcui_demo";

UI::UIRect ToUIRect(const ImVec2& minPoint, const ImVec2& size) {
    return UI::UIRect(minPoint.x, minPoint.y, size.x, size.y);
}

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 DrawHostedPreviewFrame(
    ImDrawList* drawList,
    const ImVec2& minPoint,
    const ImVec2& size) {
    if (drawList == nullptr || size.x <= 1.0f || size.y <= 1.0f) {
        return;
    }

    const ImVec2 maxPoint(minPoint.x + size.x, minPoint.y + size.y);
    drawList->AddRect(minPoint, maxPoint, kPreviewFrameColor, 8.0f, 0, 1.0f);
}

void DrawHostedPreviewPlaceholder(
    ImDrawList* drawList,
    const ImVec2& minPoint,
    const ImVec2& size,
    const char* title,
    const char* subtitle) {
    if (drawList == nullptr || size.x <= 1.0f || size.y <= 1.0f) {
        return;
    }

    const ImVec2 maxPoint(minPoint.x + size.x, minPoint.y + size.y);
    drawList->AddRectFilled(minPoint, maxPoint, kPreviewPlaceholderFill, 8.0f);
    drawList->AddRect(minPoint, maxPoint, kPreviewFrameColor, 8.0f, 0, 1.0f);
    drawList->AddText(ImVec2(minPoint.x + 14.0f, minPoint.y + 14.0f), kPreviewPlaceholderText, title);
    if (subtitle != nullptr && subtitle[0] != '\0') {
        drawList->AddText(
            ImVec2(minPoint.x + 14.0f, minPoint.y + 36.0f),
            kPreviewPlaceholderSubtleText,
            subtitle);
    }
}

void DrawRectOverlay(
    ImDrawList* drawList,
    ::XCEngine::Editor::XCUIBackend::XCUIDemoRuntime& runtime,
    const std::string& elementId,
    ImU32 color,
    const char* label) {
    if (drawList == nullptr || elementId.empty()) {
        return;
    }

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

    const ImVec2 minPoint(rect.x, rect.y);
    const ImVec2 maxPoint(rect.x + rect.width, rect.y + rect.height);
    drawList->AddRect(minPoint, maxPoint, color, 6.0f, 0, 2.0f);
    if (label != nullptr && label[0] != '\0') {
        drawList->AddText(ImVec2(minPoint.x + 4.0f, minPoint.y + 4.0f), color, label);
    }
}

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)) {
    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 = {};
}

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);

    ImGui::BeginChild("XCUIDemoCanvasHost", ImVec2(0.0f, canvasHeight), true, ImGuiWindowFlags_NoScrollWithMouse);
    const ImVec2 canvasHostMin = ImGui::GetCursorScreenPos();
    const ImVec2 availableSize = ImGui::GetContentRegionAvail();
    const float topInset = m_showCanvasHud ? (kCanvasHudHeight + kCanvasHudPadding) : 0.0f;
    const ImVec2 canvasMin(canvasHostMin.x, canvasHostMin.y + topInset);
    const ImVec2 canvasSize(
        availableSize.x,
        (std::max)(0.0f, availableSize.y - topInset));
    const bool validCanvas = canvasSize.x > 1.0f && canvasSize.y > 1.0f;
    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 =
        validCanvas &&
        nativeHostedPreview &&
        m_previewPresenter != nullptr &&
        m_previewPresenter->TryGetSurfaceImage(kPreviewDebugName, hostedSurfaceImage);
    const char* const previewPathLabel = GetPreviewPathLabel(nativeHostedPreview);
    ImDrawList* drawList = ImGui::GetWindowDrawList();

    if (validCanvas) {
        ImGui::SetCursorScreenPos(canvasMin);
        if (showHostedSurfaceImage) {
            ImGui::Image(hostedSurfaceImage.textureId, canvasSize, hostedSurfaceImage.uvMin, hostedSurfaceImage.uvMax);
            DrawHostedPreviewFrame(drawList, canvasMin, canvasSize);
        } else {
            ImGui::InvisibleButton("##XCUIDemoCanvas", canvasSize);
            const char* 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.";
            DrawHostedPreviewPlaceholder(
                drawList,
                canvasMin,
                canvasSize,
                nativeHostedPreview ? "Native XCUI preview pending" : "Legacy XCUI canvas host",
                placeholderSubtitle);
        }
    } else {
        ImGui::Dummy(ImVec2(0.0f, 0.0f));
    }

    ::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());
    const UI::UIRect canvasRect = ToUIRect(canvasMin, canvasSize);

    ::XCEngine::Editor::XCUIBackend::XCUIInputBridgeFrameSnapshot snapshot = {};
    if (m_inputSource != nullptr) {
        bridgeOptions.hasPointerInsideOverride = true;
        bridgeOptions.windowFocused = ImGui::IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows);
        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 && ImGui::IsItemHovered();
        bridgeOptions.windowFocused = ImGui::IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows);
        snapshot = ::XCEngine::Editor::XCUIBackend::ImGuiXCUIInputAdapter::CaptureSnapshot(
            ImGui::GetIO(),
            bridgeOptions);
    }

    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.targetDrawList = drawList;
        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 ImVec2 hudMin(canvasHostMin.x + 8.0f, canvasHostMin.y + 8.0f);
        const ImVec2 hudMax(
            canvasHostMin.x + (std::min)(availableSize.x - 8.0f, 430.0f),
            canvasHostMin.y + kCanvasHudHeight);
        drawList->AddRectFilled(
            hudMin,
            hudMax,
            IM_COL32(16, 22, 30, 220),
            8.0f);
        drawList->AddRect(
            hudMin,
            hudMax,
            IM_COL32(52, 72, 96, 255),
            8.0f,
            0,
            1.0f);

        ImGui::SetCursorScreenPos(ImVec2(hudMin.x + 10.0f, hudMin.y + 8.0f));
        ImGui::BeginGroup();
        ImGui::TextUnformatted("XCUI Runtime");
        ImGui::Text("%s | %s", previewPathLabel, previewStateLabel);
        ImGui::TextUnformatted(stats.statusMessage.c_str());
        ImGui::Text(
            "Tree %llu | Elements %zu | Commands %zu",
            static_cast<unsigned long long>(stats.treeGeneration),
            stats.elementCount,
            stats.commandCount);
        ImGui::Text(
            "Submit %zu/%zu | Flush %zu/%zu",
            m_lastPreviewStats.submittedDrawListCount,
            m_lastPreviewStats.submittedCommandCount,
            m_lastPreviewStats.flushedDrawListCount,
            m_lastPreviewStats.flushedCommandCount);
        ImGui::EndGroup();
    }

    if (m_showDebugRects && validCanvas && (!nativeHostedPreview || showHostedSurfaceImage)) {
        DrawRectOverlay(drawList, m_runtime, stats.hoveredElementId, IM_COL32(255, 195, 64, 255), "hover");
        DrawRectOverlay(drawList, m_runtime, stats.focusedElementId, IM_COL32(64, 214, 255, 255), "focus");
        DrawRectOverlay(drawList, m_runtime, "toggleAccent", IM_COL32(150, 255, 150, 160), "toggle");
    }
    ImGui::EndChild();

    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