#include <gtest/gtest.h>

#include "XCUIBackend/ImGuiTextAtlasProvider.h"

#include <imgui.h>

#include <cstdint>

namespace {

using XCEngine::Editor::XCUIBackend::IXCUITextAtlasProvider;
using XCEngine::Editor::XCUIBackend::ImGuiTextAtlasProvider;

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

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

void BuildDefaultFontAtlas() {
    ImGuiIO& io = ImGui::GetIO();
    if (io.Fonts->Fonts.empty()) {
        io.Fonts->AddFontDefault();
    }

    unsigned char* pixels = nullptr;
    int width = 0;
    int height = 0;
    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
}

TEST(ImGuiTextAtlasProviderTest, ReturnsEmptyResultsWhenNoContextIsAvailable) {
    ImGuiTextAtlasProvider provider = {};
    IXCUITextAtlasProvider::AtlasTextureView atlasView = {};
    IXCUITextAtlasProvider::FontInfo fontInfo = {};
    IXCUITextAtlasProvider::BakedFontInfo bakedFontInfo = {};
    IXCUITextAtlasProvider::GlyphInfo glyphInfo = {};

    EXPECT_EQ(provider.GetContext(), nullptr);
    EXPECT_FALSE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, atlasView));
    EXPECT_EQ(provider.GetFontCount(), 0u);
    EXPECT_FALSE(provider.GetDefaultFont().IsValid());
    EXPECT_FALSE(provider.GetFontInfo({}, fontInfo));
    EXPECT_FALSE(provider.GetBakedFontInfo({}, 14.0f, bakedFontInfo));
    EXPECT_FALSE(provider.FindGlyph({}, 14.0f, 'A', glyphInfo));
}

TEST(ImGuiTextAtlasProviderTest, ExposesAtlasAndGlyphDataFromExplicitContext) {
    ImGuiContextScope contextScope;
    BuildDefaultFontAtlas();

    ImGuiTextAtlasProvider provider(ImGui::GetCurrentContext());

    IXCUITextAtlasProvider::AtlasTextureView atlasView = {};
    ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, atlasView));
    EXPECT_TRUE(atlasView.IsValid());
    EXPECT_EQ(atlasView.format, IXCUITextAtlasProvider::PixelFormat::RGBA32);
    EXPECT_GT(atlasView.atlasStorageKey, 0u);
    EXPECT_GT(atlasView.pixelDataKey, 0u);

    const IXCUITextAtlasProvider::FontHandle defaultFont = provider.GetDefaultFont();
    ASSERT_TRUE(defaultFont.IsValid());
    ASSERT_GE(provider.GetFontCount(), 1u);

    IXCUITextAtlasProvider::FontInfo fontInfo = {};
    ASSERT_TRUE(provider.GetFontInfo(defaultFont, fontInfo));
    EXPECT_TRUE(fontInfo.handle.IsValid());
    EXPECT_GT(fontInfo.nominalSize, 0.0f);

    IXCUITextAtlasProvider::BakedFontInfo bakedFontInfo = {};
    ASSERT_TRUE(provider.GetBakedFontInfo(defaultFont, 0.0f, bakedFontInfo));
    EXPECT_GT(bakedFontInfo.lineHeight, 0.0f);
    EXPECT_GT(bakedFontInfo.rasterizerDensity, 0.0f);

    IXCUITextAtlasProvider::GlyphInfo glyphInfo = {};
    ASSERT_TRUE(provider.FindGlyph(defaultFont, 0.0f, 'A', glyphInfo));
    EXPECT_EQ(glyphInfo.requestedCodepoint, static_cast<std::uint32_t>('A'));
    EXPECT_GT(glyphInfo.advanceX, 0.0f);
    EXPECT_GE(glyphInfo.u1, glyphInfo.u0);
    EXPECT_GE(glyphInfo.v1, glyphInfo.v0);
}

} // namespace