#include <gtest/gtest.h>

#include "XCUIBackend/ImGuiTransitionBackend.h"

#include <XCEngine/UI/DrawData.h>

#include <imgui.h>

namespace {

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

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

} // namespace

TEST(XCUIImGuiTransitionBackendTest, BeginFrameResetsPendingState) {
    ImGuiContextScope contextScope;

    XCEngine::Editor::XCUIBackend::ImGuiTransitionBackend backend = {};
    XCEngine::UI::UIDrawList drawList("Pending");
    drawList.AddFilledRect(
        XCEngine::UI::UIRect(0.0f, 0.0f, 16.0f, 16.0f),
        XCEngine::UI::UIColor(1.0f, 0.0f, 0.0f, 1.0f));

    backend.BeginFrame();
    backend.Submit(drawList);
    ASSERT_EQ(backend.GetPendingDrawListCount(), 1u);
    ASSERT_EQ(backend.GetPendingCommandCount(), 1u);

    backend.BeginFrame();
    EXPECT_EQ(backend.GetPendingDrawListCount(), 0u);
    EXPECT_EQ(backend.GetPendingCommandCount(), 0u);
}

TEST(XCUIImGuiTransitionBackendTest, EndFrameFlushesCommandsToImGuiDrawList) {
    ImGuiContextScope contextScope;
    ImGuiIO& io = ImGui::GetIO();
    io.DisplaySize = ImVec2(1280.0f, 720.0f);
    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));

    XCEngine::Editor::XCUIBackend::ImGuiTransitionBackend backend = {};
    XCEngine::UI::UIDrawList drawList("FlushTest");
    drawList.PushClipRect(XCEngine::UI::UIRect(0.0f, 0.0f, 220.0f, 160.0f));
    drawList.AddFilledRect(
        XCEngine::UI::UIRect(10.0f, 10.0f, 60.0f, 40.0f),
        XCEngine::UI::UIColor(0.1f, 0.2f, 0.3f, 1.0f),
        4.0f);
    drawList.AddRectOutline(
        XCEngine::UI::UIRect(10.0f, 10.0f, 60.0f, 40.0f),
        XCEngine::UI::UIColor(0.9f, 0.9f, 0.9f, 1.0f),
        2.0f,
        4.0f);
    drawList.AddText(
        XCEngine::UI::UIPoint(18.0f, 26.0f),
        "Backend",
        XCEngine::UI::UIColor(1.0f, 1.0f, 1.0f, 1.0f),
        16.0f);
    drawList.AddImage(
        XCEngine::UI::UIRect(90.0f, 12.0f, 32.0f, 32.0f),
        XCEngine::UI::UITextureHandle{ 0x100u, 32u, 32u },
        XCEngine::UI::UIColor(1.0f, 1.0f, 1.0f, 1.0f));
    drawList.PopClipRect();

    backend.BeginFrame();
    backend.Submit(drawList);

    ImGui::NewFrame();
    ASSERT_TRUE(ImGui::Begin("XCUIBackendTest"));
    ImDrawList* targetDrawList = ImGui::GetWindowDrawList();
    ASSERT_NE(targetDrawList, nullptr);

    const bool flushed = backend.EndFrame(targetDrawList);

    ImGui::End();
    ImGui::EndFrame();

    EXPECT_TRUE(flushed);
    EXPECT_EQ(backend.GetLastFlushedDrawListCount(), 1u);
    EXPECT_EQ(backend.GetLastFlushedCommandCount(), 6u);
    EXPECT_EQ(backend.GetPendingCommandCount(), 0u);
    EXPECT_GT(targetDrawList->VtxBuffer.Size, 0);
    EXPECT_GT(targetDrawList->CmdBuffer.Size, 0);
}