#include <gtest/gtest.h>

#include "panels/XCUIDemoPanel.h"

#include "XCUIBackend/XCUIHostedPreviewPresenter.h"
#include "XCUIBackend/XCUIPanelCanvasHost.h"

#include <imgui.h>

#include <memory>
#include <string>
#include <string_view>

namespace {

using XCEngine::Editor::XCUIBackend::IXCUIHostedPreviewPresenter;
using XCEngine::Editor::XCUIBackend::IXCUIPanelCanvasHost;
using XCEngine::Editor::XCUIBackend::XCUIHostedPreviewFrame;
using XCEngine::Editor::XCUIBackend::XCUIHostedPreviewStats;
using XCEngine::Editor::XCUIBackend::XCUIPanelCanvasRequest;
using XCEngine::Editor::XCUIBackend::XCUIPanelCanvasSession;
using XCEngine::NewEditor::XCUIDemoPanel;

class ImGuiContextScope {
public:
    ImGuiContextScope() {
        IMGUI_CHECKVERSION();
        ImGui::CreateContext();
        ImGui::StyleColorsDark();
    }

    ~ImGuiContextScope() {
        ImGui::DestroyContext();
    }
};

void PrepareImGui(float width = 1280.0f, float height = 900.0f) {
    ImGuiIO& io = ImGui::GetIO();
    io.DisplaySize = ImVec2(width, height);
    io.DeltaTime = 1.0f / 60.0f;
    unsigned char* fontPixels = nullptr;
    int fontWidth = 0;
    int fontHeight = 0;
    io.Fonts->GetTexDataAsRGBA32(&fontPixels, &fontWidth, &fontHeight);
    io.Fonts->SetTexID(static_cast<ImTextureID>(1));
}

class RecordingHostedPreviewPresenter final : public IXCUIHostedPreviewPresenter {
public:
    bool Present(const XCUIHostedPreviewFrame& frame) override {
        ++presentCallCount;
        lastCanvasRect = frame.canvasRect;
        lastLogicalSize = frame.logicalSize;
        lastDebugName = frame.debugName != nullptr ? frame.debugName : "";

        m_lastStats = {};
        if (frame.drawData == nullptr) {
            return false;
        }

        lastDrawListCount = frame.drawData->GetDrawListCount();
        lastCommandCount = frame.drawData->GetTotalCommandCount();
        m_lastStats.presented = true;
        m_lastStats.submittedDrawListCount = lastDrawListCount;
        m_lastStats.submittedCommandCount = lastCommandCount;
        return true;
    }

    const XCUIHostedPreviewStats& GetLastStats() const override {
        return m_lastStats;
    }

    std::size_t presentCallCount = 0u;
    XCEngine::UI::UIRect lastCanvasRect = {};
    XCEngine::UI::UISize lastLogicalSize = {};
    std::size_t lastDrawListCount = 0u;
    std::size_t lastCommandCount = 0u;
    std::string lastDebugName = {};

private:
    XCUIHostedPreviewStats m_lastStats = {};
};

class StubCanvasHost final : public IXCUIPanelCanvasHost {
public:
    const char* GetDebugName() const override {
        return "StubCanvasHost";
    }

    XCUIPanelCanvasSession BeginCanvas(const XCUIPanelCanvasRequest& request) override {
        lastRequest = request;
        ++beginCanvasCallCount;
        return session;
    }

    void DrawFilledRect(
        const XCEngine::UI::UIRect&,
        const XCEngine::UI::UIColor&,
        float) override {
    }

    void DrawOutlineRect(
        const XCEngine::UI::UIRect&,
        const XCEngine::UI::UIColor&,
        float,
        float) override {
    }

    void DrawText(
        const XCEngine::UI::UIPoint&,
        std::string_view,
        const XCEngine::UI::UIColor&,
        float) override {
    }

    void EndCanvas() override {
        ++endCanvasCallCount;
    }

    std::size_t beginCanvasCallCount = 0u;
    std::size_t endCanvasCallCount = 0u;
    XCUIPanelCanvasRequest lastRequest = {};
    XCUIPanelCanvasSession session = {
        XCEngine::UI::UIRect(0.0f, 0.0f, 960.0f, 640.0f),
        XCEngine::UI::UIRect(12.0f, 18.0f, 936.0f, 512.0f),
        XCEngine::UI::UIPoint(120.0f, 140.0f),
        true,
        true,
        true
    };
};

void RenderPanelFrame(XCUIDemoPanel& panel, ImGuiContextScope&) {
    PrepareImGui();
    ImGui::NewFrame();
    panel.Render();
    ImGui::Render();
}

TEST(NewEditorXCUIDemoPanelTest, DefaultConstructionDoesNotAutoCreateHostedPreviewPresenter) {
    ImGuiContextScope contextScope;

    auto canvasHost = std::make_unique<StubCanvasHost>();
    XCUIDemoPanel panel;
    panel.SetCanvasHost(std::move(canvasHost));

    RenderPanelFrame(panel, contextScope);

    const XCUIHostedPreviewStats& stats = panel.GetLastPreviewStats();
    EXPECT_FALSE(stats.presented);
    EXPECT_FALSE(stats.queuedToNativePass);
    EXPECT_EQ(stats.submittedDrawListCount, 0u);
    EXPECT_EQ(stats.submittedCommandCount, 0u);
    EXPECT_EQ(stats.flushedDrawListCount, 0u);
    EXPECT_EQ(stats.flushedCommandCount, 0u);
}

TEST(NewEditorXCUIDemoPanelTest, ConstructorUsesGenericNullCanvasHostUntilOuterLayerInjectsOne) {
    ImGuiContextScope contextScope;

    auto previewPresenter = std::make_unique<RecordingHostedPreviewPresenter>();
    RecordingHostedPreviewPresenter* previewPresenterPtr = previewPresenter.get();

    XCUIDemoPanel panel(nullptr, std::move(previewPresenter));
    RenderPanelFrame(panel, contextScope);

    ASSERT_EQ(previewPresenterPtr->presentCallCount, 1u);
    EXPECT_EQ(previewPresenterPtr->lastDebugName, "XCUI Demo");
    EXPECT_FLOAT_EQ(previewPresenterPtr->lastCanvasRect.x, 0.0f);
    EXPECT_GT(previewPresenterPtr->lastCanvasRect.y, 0.0f);
    EXPECT_FLOAT_EQ(previewPresenterPtr->lastCanvasRect.width, 0.0f);
    EXPECT_GT(previewPresenterPtr->lastCanvasRect.height, 0.0f);
    EXPECT_FLOAT_EQ(previewPresenterPtr->lastLogicalSize.width, 0.0f);
    EXPECT_FLOAT_EQ(
        previewPresenterPtr->lastLogicalSize.height,
        previewPresenterPtr->lastCanvasRect.height);
}

TEST(NewEditorXCUIDemoPanelTest, ClearingHostedPreviewPresenterDoesNotRestoreImGuiFallback) {
    ImGuiContextScope contextScope;

    auto previewPresenter = std::make_unique<RecordingHostedPreviewPresenter>();
    RecordingHostedPreviewPresenter* previewPresenterPtr = previewPresenter.get();
    auto canvasHost = std::make_unique<StubCanvasHost>();

    XCUIDemoPanel panel(nullptr, std::move(previewPresenter));
    panel.SetCanvasHost(std::move(canvasHost));

    RenderPanelFrame(panel, contextScope);
    ASSERT_EQ(previewPresenterPtr->presentCallCount, 1u);
    EXPECT_TRUE(panel.GetLastPreviewStats().presented);

    panel.SetHostedPreviewPresenter(nullptr);
    RenderPanelFrame(panel, contextScope);

    const XCUIHostedPreviewStats& stats = panel.GetLastPreviewStats();
    EXPECT_FALSE(stats.presented);
    EXPECT_FALSE(stats.queuedToNativePass);
    EXPECT_EQ(stats.submittedDrawListCount, 0u);
    EXPECT_EQ(stats.submittedCommandCount, 0u);
    EXPECT_EQ(stats.flushedDrawListCount, 0u);
    EXPECT_EQ(stats.flushedCommandCount, 0u);
}

} // namespace