#include <gtest/gtest.h>

#include "XCUIBackend/XCUIStandaloneTextAtlasProvider.h"

#include <cstdint>

namespace {

using XCEngine::Editor::XCUIBackend::IXCUITextAtlasProvider;
using XCEngine::Editor::XCUIBackend::XCUIStandaloneTextAtlasProvider;

TEST(XCUIStandaloneTextAtlasProviderTest, BuildsDefaultEditorAtlasWithoutImGuiContext) {
    XCUIStandaloneTextAtlasProvider provider = {};
    IXCUITextAtlasProvider::AtlasTextureView atlasView = {};
    IXCUITextAtlasProvider::AtlasTextureView alphaView = {};
    ASSERT_TRUE(provider.IsReady());
    ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, atlasView));
    ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::Alpha8, alphaView));
    EXPECT_TRUE(atlasView.IsValid());
    EXPECT_TRUE(alphaView.IsValid());
    EXPECT_EQ(atlasView.format, IXCUITextAtlasProvider::PixelFormat::RGBA32);
    EXPECT_EQ(alphaView.format, IXCUITextAtlasProvider::PixelFormat::Alpha8);
    EXPECT_GT(provider.GetFontCount(), 0u);
}

TEST(XCUIStandaloneTextAtlasProviderTest, ExposesDefaultFontMetricsAndGlyphs) {
    XCUIStandaloneTextAtlasProvider provider = {};
    const IXCUITextAtlasProvider::FontHandle defaultFont = provider.GetDefaultFont();
    ASSERT_TRUE(defaultFont.IsValid());

    IXCUITextAtlasProvider::FontInfo fontInfo = {};
    ASSERT_TRUE(provider.GetFontInfo(defaultFont, fontInfo));
    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, static_cast<std::uint32_t>('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);
}

TEST(XCUIStandaloneTextAtlasProviderTest, RebuildsAfterResetAndRejectsQueriesWhileUnready) {
    XCUIStandaloneTextAtlasProvider provider = {};
    const IXCUITextAtlasProvider::FontHandle defaultFont = provider.GetDefaultFont();
    ASSERT_TRUE(defaultFont.IsValid());

    provider.Reset();

    IXCUITextAtlasProvider::AtlasTextureView atlasView = {};
    IXCUITextAtlasProvider::FontInfo fontInfo = {};
    IXCUITextAtlasProvider::BakedFontInfo bakedFontInfo = {};
    IXCUITextAtlasProvider::GlyphInfo glyphInfo = {};

    EXPECT_FALSE(provider.IsReady());
    EXPECT_FALSE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, atlasView));
    EXPECT_EQ(provider.GetFontCount(), 0u);
    EXPECT_FALSE(provider.GetDefaultFont().IsValid());
    EXPECT_FALSE(provider.GetFontInfo(defaultFont, fontInfo));
    EXPECT_FALSE(provider.GetBakedFontInfo(defaultFont, 18.0f, bakedFontInfo));
    EXPECT_FALSE(provider.FindGlyph(defaultFont, 18.0f, static_cast<std::uint32_t>('A'), glyphInfo));

    ASSERT_TRUE(provider.RebuildDefaultEditorAtlas());
    ASSERT_TRUE(provider.IsReady());
    ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, atlasView));
    EXPECT_TRUE(atlasView.IsValid());
}

TEST(XCUIStandaloneTextAtlasProviderTest, ResolvesGlyphsForNonNominalRequestedFontSizes) {
    XCUIStandaloneTextAtlasProvider provider = {};
    const IXCUITextAtlasProvider::FontHandle defaultFont = provider.GetDefaultFont();
    ASSERT_TRUE(defaultFont.IsValid());

    IXCUITextAtlasProvider::BakedFontInfo bakedFontInfo = {};
    ASSERT_TRUE(provider.GetBakedFontInfo(defaultFont, 13.0f, bakedFontInfo));
    EXPECT_GT(bakedFontInfo.lineHeight, 0.0f);
    EXPECT_GT(bakedFontInfo.rasterizerDensity, 0.0f);

    IXCUITextAtlasProvider::GlyphInfo glyphInfo = {};
    ASSERT_TRUE(provider.FindGlyph(defaultFont, 13.0f, static_cast<std::uint32_t>('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);
}

TEST(XCUIStandaloneTextAtlasProviderTest, LazilyAddsGlyphsOutsideThePrebakedAsciiRanges) {
    XCUIStandaloneTextAtlasProvider provider = {};
    const IXCUITextAtlasProvider::FontHandle defaultFont = provider.GetDefaultFont();
    ASSERT_TRUE(defaultFont.IsValid());

    IXCUITextAtlasProvider::AtlasTextureView beforeView = {};
    ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, beforeView));

    constexpr std::uint32_t dynamicCodepoint = 0x4E2Du;
    IXCUITextAtlasProvider::GlyphInfo glyphInfo = {};
    ASSERT_TRUE(provider.FindGlyph(defaultFont, 16.0f, dynamicCodepoint, glyphInfo));

    IXCUITextAtlasProvider::AtlasTextureView refreshedView = {};
    ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, refreshedView));
    EXPECT_EQ(refreshedView.atlasStorageKey, beforeView.atlasStorageKey);
    EXPECT_EQ(glyphInfo.requestedCodepoint, dynamicCodepoint);

    if (refreshedView.pixelDataKey != beforeView.pixelDataKey) {
        EXPECT_EQ(glyphInfo.resolvedCodepoint, dynamicCodepoint);
        EXPECT_GT(glyphInfo.advanceX, 0.0f);
        EXPECT_TRUE(glyphInfo.visible);

        IXCUITextAtlasProvider::GlyphInfo secondLookup = {};
        ASSERT_TRUE(provider.FindGlyph(defaultFont, 16.0f, dynamicCodepoint, secondLookup));
        EXPECT_EQ(secondLookup.requestedCodepoint, dynamicCodepoint);
        EXPECT_EQ(secondLookup.resolvedCodepoint, dynamicCodepoint);

        IXCUITextAtlasProvider::AtlasTextureView secondView = {};
        ASSERT_TRUE(provider.GetAtlasTextureView(IXCUITextAtlasProvider::PixelFormat::RGBA32, secondView));
        EXPECT_EQ(secondView.pixelDataKey, refreshedView.pixelDataKey);
        return;
    }

    if (glyphInfo.resolvedCodepoint != dynamicCodepoint) {
        EXPECT_EQ(glyphInfo.resolvedCodepoint, static_cast<std::uint32_t>('?'));
        EXPECT_GT(glyphInfo.advanceX, 0.0f);
        EXPECT_TRUE(glyphInfo.visible);
        return;
    }

    if (!glyphInfo.visible) {
        EXPECT_GE(glyphInfo.advanceX, 0.0f);
        return;
    }

    if (glyphInfo.resolvedCodepoint == dynamicCodepoint) {
        EXPECT_NE(refreshedView.pixelDataKey, beforeView.pixelDataKey);
    }
    EXPECT_GT(glyphInfo.advanceX, 0.0f);
    EXPECT_TRUE(glyphInfo.visible);
}

TEST(XCUIStandaloneTextAtlasProviderTest, MissingGlyphFallsBackToQuestionMarkWhenFontCannotRasterizeIt) {
    XCUIStandaloneTextAtlasProvider provider = {};
    const IXCUITextAtlasProvider::FontHandle defaultFont = provider.GetDefaultFont();
    ASSERT_TRUE(defaultFont.IsValid());

    IXCUITextAtlasProvider::GlyphInfo glyphInfo = {};
    ASSERT_TRUE(provider.FindGlyph(defaultFont, 16.0f, 0x10FFFFu, glyphInfo));
    EXPECT_EQ(glyphInfo.requestedCodepoint, 0x10FFFFu);
    EXPECT_EQ(glyphInfo.resolvedCodepoint, static_cast<std::uint32_t>('?'));
    EXPECT_GT(glyphInfo.advanceX, 0.0f);
    EXPECT_TRUE(glyphInfo.visible);
}

} // namespace