#include <gtest/gtest.h>

#include "panels/XCUILayoutLabPanel.h"

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

#include <imgui.h>

#include <functional>
#include <memory>
#include <string>

namespace {

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

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 StubHostedPreviewPresenter final : public IXCUIHostedPreviewPresenter {
public:
    bool Present(const XCUIHostedPreviewFrame& frame) override {
        m_lastStats = {};
        m_lastStats.presented = frame.drawData != nullptr;
        return m_lastStats.presented;
    }

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

private:
    XCUIHostedPreviewStats m_lastStats = {};
};

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

    XCUIPanelCanvasSession BeginCanvas(const XCUIPanelCanvasRequest&) override {
        return m_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 {
    }

    void SetPointerPosition(const XCEngine::UI::UIPoint& position) {
        m_session.pointerPosition = position;
    }

    void SetHovered(bool hovered) {
        m_session.hovered = hovered;
    }

    void SetWindowFocused(bool focused) {
        m_session.windowFocused = focused;
    }

private:
    XCUIPanelCanvasSession m_session = {
        XCEngine::UI::UIRect(0.0f, 0.0f, 960.0f, 640.0f),
        XCEngine::UI::UIRect(0.0f, 0.0f, 960.0f, 640.0f),
        XCEngine::UI::UIPoint(120.0f, 120.0f),
        true,
        true,
        true
    };
};

void RenderPanelFrame(
    XCUILayoutLabPanel& panel,
    ImGuiContextScope&,
    const std::function<void(ImGuiIO&)>& configureIo = nullptr) {
    PrepareImGui();
    if (configureIo) {
        configureIo(ImGui::GetIO());
    }

    ImGui::NewFrame();
    panel.Render();
    ImGui::Render();
}

void ClickElement(
    XCUILayoutLabPanel& panel,
    StubCanvasHost& canvasHost,
    const std::string& elementId,
    ImGuiContextScope& contextScope) {
    XCEngine::UI::UIRect elementRect = {};
    ASSERT_TRUE(panel.TryGetElementRect(elementId, elementRect));
    const XCEngine::UI::UIPoint clickPoint(
        elementRect.x + elementRect.width * 0.5f,
        elementRect.y + elementRect.height * 0.5f);

    canvasHost.SetPointerPosition(clickPoint);
    canvasHost.SetHovered(true);
    RenderPanelFrame(
        panel,
        contextScope,
        [clickPoint](ImGuiIO& io) {
            io.AddMousePosEvent(clickPoint.x, clickPoint.y);
            io.AddMouseButtonEvent(ImGuiMouseButton_Left, true);
        });
    RenderPanelFrame(
        panel,
        contextScope,
        [clickPoint](ImGuiIO& io) {
            io.AddMousePosEvent(clickPoint.x, clickPoint.y);
            io.AddMouseButtonEvent(ImGuiMouseButton_Left, false);
        });
}

void PressKeyOnce(
    XCUILayoutLabPanel& panel,
    ImGuiContextScope& contextScope,
    ImGuiKey key) {
    RenderPanelFrame(
        panel,
        contextScope,
        [key](ImGuiIO& io) {
            io.AddKeyEvent(key, true);
        });
    RenderPanelFrame(
        panel,
        contextScope,
        [key](ImGuiIO& io) {
            io.AddKeyEvent(key, false);
        });
}

TEST(NewEditorXCUILayoutLabPanelTest, MapsPreviousNextHomeAndEndIntoRuntimeNavigation) {
    ImGuiContextScope contextScope;

    auto previewPresenter = std::make_unique<StubHostedPreviewPresenter>();
    auto canvasHost = std::make_unique<StubCanvasHost>();
    StubCanvasHost* canvasHostPtr = canvasHost.get();
    ImGuiXCUIInputSnapshotSource inputSource(nullptr);

    XCUILayoutLabPanel panel(&inputSource, std::move(previewPresenter), std::move(canvasHost));
    panel.SetHostedPreviewEnabled(false);

    RenderPanelFrame(panel, contextScope);
    ClickElement(panel, *canvasHostPtr, "assetLighting", contextScope);
    ASSERT_EQ(panel.GetFrameResult().stats.selectedElementId, "assetLighting");

    canvasHostPtr->SetHovered(false);
    canvasHostPtr->SetWindowFocused(true);

    PressKeyOnce(panel, contextScope, ImGuiKey_DownArrow);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "assetMaterials");

    PressKeyOnce(panel, contextScope, ImGuiKey_UpArrow);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "assetLighting");

    PressKeyOnce(panel, contextScope, ImGuiKey_End);
    const std::string endSelection = panel.GetFrameResult().stats.selectedElementId;
    ASSERT_FALSE(endSelection.empty());
    EXPECT_NE(endSelection, "assetLighting");

    PressKeyOnce(panel, contextScope, ImGuiKey_Home);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "assetLighting");
}

TEST(NewEditorXCUILayoutLabPanelTest, MapsCollapseAndExpandIntoRuntimeNavigation) {
    ImGuiContextScope contextScope;

    auto previewPresenter = std::make_unique<StubHostedPreviewPresenter>();
    auto canvasHost = std::make_unique<StubCanvasHost>();
    StubCanvasHost* canvasHostPtr = canvasHost.get();
    ImGuiXCUIInputSnapshotSource inputSource(nullptr);

    XCUILayoutLabPanel panel(&inputSource, std::move(previewPresenter), std::move(canvasHost));
    panel.SetHostedPreviewEnabled(false);

    RenderPanelFrame(panel, contextScope);
    ClickElement(panel, *canvasHostPtr, "treeScenes", contextScope);
    ASSERT_EQ(panel.GetFrameResult().stats.selectedElementId, "treeScenes");

    canvasHostPtr->SetHovered(false);
    canvasHostPtr->SetWindowFocused(true);

    PressKeyOnce(panel, contextScope, ImGuiKey_LeftArrow);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "treeAssetsRoot");

    PressKeyOnce(panel, contextScope, ImGuiKey_LeftArrow);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "treeAssetsRoot");
    EXPECT_EQ(panel.GetFrameResult().stats.expandedTreeItemCount, 0u);

    PressKeyOnce(panel, contextScope, ImGuiKey_RightArrow);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "treeAssetsRoot");
    EXPECT_EQ(panel.GetFrameResult().stats.expandedTreeItemCount, 1u);

    PressKeyOnce(panel, contextScope, ImGuiKey_RightArrow);
    EXPECT_EQ(panel.GetFrameResult().stats.selectedElementId, "treeScenes");
}

TEST(NewEditorXCUILayoutLabPanelTest, DefaultFallbackDoesNotCreateImplicitHostedPreviewPresenter) {
    ImGuiContextScope contextScope;

    XCUILayoutLabPanel panel(nullptr);

    RenderPanelFrame(panel, contextScope);

    EXPECT_FALSE(panel.IsUsingNativeHostedPreview());
    EXPECT_FALSE(panel.GetLastPreviewStats().presented);
    EXPECT_EQ(panel.GetLastPreviewStats().submittedDrawListCount, 0u);
    EXPECT_EQ(panel.GetLastPreviewStats().submittedCommandCount, 0u);
}

} // namespace