#include <gtest/gtest.h>
#include <XCEngine/Core/Asset/ArtifactFormats.h>
#include <XCEngine/Core/Asset/AssetDatabase.h>
#include <XCEngine/Resources/Material/MaterialLoader.h>
#include <XCEngine/Core/Asset/ResourceManager.h>
#include <XCEngine/Core/Asset/ResourceTypes.h>
#include <XCEngine/Core/Containers/Array.h>

#include <chrono>
#include <cstdio>
#include <filesystem>
#include <fstream>
#include <thread>
#include <vector>

using namespace XCEngine::Resources;
using namespace XCEngine::Containers;

namespace {

std::string GetMeshFixturePath(const char* fileName) {
    return (std::filesystem::path(XCENGINE_TEST_FIXTURES_DIR) / "Resources" / "Mesh" / fileName).string();
}

void WriteArtifactString(std::ofstream& output, const XCEngine::Containers::String& value) {
    const XCEngine::Core::uint32 length = static_cast<XCEngine::Core::uint32>(value.Length());
    output.write(reinterpret_cast<const char*>(&length), sizeof(length));
    if (length > 0) {
        output.write(value.CStr(), length);
    }
}

bool PumpAsyncLoadsUntilIdle(ResourceManager& manager,
                             std::chrono::milliseconds timeout = std::chrono::milliseconds(4000)) {
    const auto deadline = std::chrono::steady_clock::now() + timeout;
    while (manager.IsAsyncLoading() && std::chrono::steady_clock::now() < deadline) {
        manager.UpdateAsyncLoads();
        std::this_thread::sleep_for(std::chrono::milliseconds(5));
    }

    manager.UpdateAsyncLoads();
    return !manager.IsAsyncLoading();
}

void FlipLastByte(const std::filesystem::path& path) {
    std::ifstream input(path, std::ios::binary);
    ASSERT_TRUE(input.is_open());

    std::vector<char> bytes(
        (std::istreambuf_iterator<char>(input)),
        std::istreambuf_iterator<char>());
    ASSERT_FALSE(bytes.empty());

    bytes.back() ^= 0x01;

    std::ofstream output(path, std::ios::binary | std::ios::trunc);
    ASSERT_TRUE(output.is_open());
    output.write(bytes.data(), static_cast<std::streamsize>(bytes.size()));
    ASSERT_TRUE(static_cast<bool>(output));
}

TEST(MaterialLoader, GetResourceType) {
    MaterialLoader loader;
    EXPECT_EQ(loader.GetResourceType(), ResourceType::Material);
}

TEST(MaterialLoader, GetSupportedExtensions) {
    MaterialLoader loader;
    auto extensions = loader.GetSupportedExtensions();
    EXPECT_GE(extensions.Size(), 1u);
}

TEST(MaterialLoader, CanLoad) {
    MaterialLoader loader;
    EXPECT_TRUE(loader.CanLoad("test.mat"));
    EXPECT_TRUE(loader.CanLoad("test.json"));
    EXPECT_TRUE(loader.CanLoad("test.xcmat"));
    EXPECT_FALSE(loader.CanLoad("test.txt"));
    EXPECT_FALSE(loader.CanLoad("test.png"));
}

TEST(MaterialLoader, LoadInvalidPath) {
    MaterialLoader loader;
    LoadResult result = loader.Load("invalid/path/material.mat");
    EXPECT_FALSE(result);
}

TEST(MaterialLoader, ResourceManagerRegistersMaterialAndShaderLoaders) {
    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();

    EXPECT_NE(manager.GetLoader(ResourceType::Material), nullptr);
    EXPECT_NE(manager.GetLoader(ResourceType::Shader), nullptr);

    manager.Shutdown();
}

TEST(MaterialLoader, LoadValidMaterialParsesRenderMetadata) {
    const std::filesystem::path shaderPath =
        std::filesystem::current_path() / "material_loader_valid_shader.hlsl";
    const std::filesystem::path materialPath =
        std::filesystem::current_path() / "material_loader_valid.material";

    {
        std::ofstream shaderFile(shaderPath);
        ASSERT_TRUE(shaderFile.is_open());
        shaderFile << "float4 MainPS() : SV_TARGET { return float4(1, 1, 1, 1); }";
    }

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{\n";
        materialFile << "  \"shader\": \"" << shaderPath.generic_string() << "\",\n";
        materialFile << "  \"renderQueue\": \"Transparent\",\n";
        materialFile << "  \"shaderPass\": \"ForwardLit\",\n";
        materialFile << "  \"tags\": {\n";
        materialFile << "    \"LightMode\": \"ForwardBase\",\n";
        materialFile << "    \"RenderType\": \"Transparent\"\n";
        materialFile << "  },\n";
        materialFile << "  \"renderState\": {\n";
        materialFile << "    \"cull\": \"Back\",\n";
        materialFile << "    \"blend\": true,\n";
        materialFile << "    \"srcBlend\": \"SrcAlpha\",\n";
        materialFile << "    \"dstBlend\": \"InvSrcAlpha\",\n";
        materialFile << "    \"depthWrite\": false,\n";
        materialFile << "    \"depthFunc\": \"LessEqual\"\n";
        materialFile << "  }\n";
        materialFile << "}";
    }

    MaterialLoader loader;
    LoadResult result = loader.Load(materialPath.string().c_str());
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    Material* material = static_cast<Material*>(result.resource);
    ASSERT_NE(material, nullptr);
    EXPECT_TRUE(material->IsValid());
    EXPECT_NE(material->GetShader(), nullptr);
    EXPECT_EQ(material->GetRenderQueue(), static_cast<XCEngine::Core::int32>(MaterialRenderQueue::Transparent));
    EXPECT_EQ(material->GetShaderPass(), "ForwardLit");
    EXPECT_EQ(material->GetTag("LightMode"), "ForwardBase");
    EXPECT_EQ(material->GetTag("RenderType"), "Transparent");
    EXPECT_EQ(material->GetRenderState().cullMode, MaterialCullMode::Back);
    EXPECT_TRUE(material->GetRenderState().blendEnable);
    EXPECT_EQ(material->GetRenderState().srcBlend, MaterialBlendFactor::SrcAlpha);
    EXPECT_EQ(material->GetRenderState().dstBlend, MaterialBlendFactor::InvSrcAlpha);
    EXPECT_FALSE(material->GetRenderState().depthWriteEnable);
    EXPECT_EQ(material->GetRenderState().depthFunc, MaterialComparisonFunc::LessEqual);

    delete material;
    std::remove(materialPath.string().c_str());
    std::remove(shaderPath.string().c_str());
}

TEST(MaterialLoader, LoadMaterialWithShaderManifestResolvesShaderPass) {
    namespace fs = std::filesystem;

    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();

    const fs::path shaderRoot = fs::temp_directory_path() / "xc_material_shader_manifest_test";
    const fs::path shaderDir = shaderRoot / "Shaders";
    const fs::path manifestPath = shaderDir / "lit.shader";
    const fs::path materialPath = shaderRoot / "manifest.material";

    fs::remove_all(shaderRoot);
    fs::create_directories(shaderDir);

    {
        std::ofstream vertexFile(shaderDir / "lit.vert.glsl");
        ASSERT_TRUE(vertexFile.is_open());
        vertexFile << "#version 430\n// MATERIAL_MANIFEST_GL_VS\nvoid main() {}\n";
    }

    {
        std::ofstream fragmentFile(shaderDir / "lit.frag.glsl");
        ASSERT_TRUE(fragmentFile.is_open());
        fragmentFile << "#version 430\n// MATERIAL_MANIFEST_GL_PS\nvoid main() {}\n";
    }

    {
        std::ofstream manifestFile(manifestPath);
        ASSERT_TRUE(manifestFile.is_open());
        manifestFile << "{\n";
        manifestFile << "  \"name\": \"ManifestLit\",\n";
        manifestFile << "  \"passes\": [\n";
        manifestFile << "    {\n";
        manifestFile << "      \"name\": \"ForwardLit\",\n";
        manifestFile << "      \"tags\": { \"LightMode\": \"ForwardBase\" },\n";
        manifestFile << "      \"variants\": [\n";
        manifestFile << "        { \"stage\": \"Vertex\", \"backend\": \"OpenGL\", \"language\": \"GLSL\", \"source\": \"lit.vert.glsl\" },\n";
        manifestFile << "        { \"stage\": \"Fragment\", \"backend\": \"OpenGL\", \"language\": \"GLSL\", \"source\": \"lit.frag.glsl\" }\n";
        manifestFile << "      ]\n";
        manifestFile << "    }\n";
        manifestFile << "  ]\n";
        manifestFile << "}\n";
    }

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{\n";
        materialFile << "  \"shader\": \"" << manifestPath.generic_string() << "\",\n";
        materialFile << "  \"shaderPass\": \"ForwardLit\",\n";
        materialFile << "  \"renderQueue\": \"Geometry\"\n";
        materialFile << "}\n";
    }

    MaterialLoader loader;
    LoadResult result = loader.Load(materialPath.string().c_str());
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    Material* material = static_cast<Material*>(result.resource);
    ASSERT_NE(material, nullptr);
    ASSERT_NE(material->GetShader(), nullptr);
    EXPECT_EQ(material->GetShaderPass(), "ForwardLit");
    ASSERT_NE(material->GetShader()->FindPass("ForwardLit"), nullptr);
    const ShaderStageVariant* vertexVariant =
        material->GetShader()->FindVariant("ForwardLit", ShaderType::Vertex, ShaderBackend::OpenGL);
    ASSERT_NE(vertexVariant, nullptr);
    EXPECT_NE(std::string(vertexVariant->sourceCode.CStr()).find("MATERIAL_MANIFEST_GL_VS"), std::string::npos);

    delete material;
    manager.Shutdown();
    fs::remove_all(shaderRoot);
}

TEST(MaterialLoader, RejectsUnknownRenderQueueName) {
    const std::filesystem::path materialPath =
        std::filesystem::current_path() / "material_loader_invalid_queue.material";

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{ \"renderQueue\": \"NotAQueue\" }";
    }

    MaterialLoader loader;
    LoadResult result = loader.Load(materialPath.string().c_str());
    EXPECT_FALSE(result);

    std::remove(materialPath.string().c_str());
}

TEST(MaterialLoader, RejectsUnknownRenderStateEnum) {
    const std::filesystem::path materialPath =
        std::filesystem::current_path() / "material_loader_invalid_render_state.material";

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{ \"renderState\": { \"cull\": \"Sideways\" } }";
    }

    MaterialLoader loader;
    LoadResult result = loader.Load(materialPath.string().c_str());
    EXPECT_FALSE(result);

    std::remove(materialPath.string().c_str());
}

TEST(MaterialLoader, ResourceManagerLoadsRelativeMaterialFromResourceRoot) {
    namespace fs = std::filesystem;

    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();

    const fs::path previousPath = fs::current_path();
    const fs::path projectRoot = fs::temp_directory_path() / "xc_material_loader_resource_root";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path materialPath = assetsDir / "relative.material";

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{\n";
        materialFile << "  \"renderQueue\": \"geometry\",\n";
        materialFile << "  \"renderState\": {\n";
        materialFile << "    \"cull\": \"back\",\n";
        materialFile << "    \"colorWriteMask\": 15\n";
        materialFile << "  }\n";
        materialFile << "}";
    }

    manager.SetResourceRoot(projectRoot.string().c_str());
    fs::current_path(projectRoot.parent_path());

    {
        const auto materialHandle = manager.Load<Material>("Assets/relative.material");
        ASSERT_TRUE(materialHandle.IsValid());
        EXPECT_EQ(materialHandle->GetRenderQueue(), static_cast<XCEngine::Core::int32>(MaterialRenderQueue::Geometry));
        EXPECT_EQ(materialHandle->GetRenderState().cullMode, MaterialCullMode::Back);
        EXPECT_EQ(materialHandle->GetRenderState().colorWriteMask, 15);
    }

    fs::current_path(previousPath);
    fs::remove_all(projectRoot);
    manager.SetResourceRoot("");
    manager.Shutdown();
}

TEST(MaterialLoader, AssetDatabaseCreatesMaterialArtifact) {
    namespace fs = std::filesystem;

    const fs::path projectRoot = fs::temp_directory_path() / "xc_material_artifact_test";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path materialPath = assetsDir / "relative.material";

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{\n";
        materialFile << "  \"renderQueue\": \"geometry\",\n";
        materialFile << "  \"renderState\": {\n";
        materialFile << "    \"cull\": \"back\"\n";
        materialFile << "  }\n";
        materialFile << "}";
    }

    AssetDatabase database;
    database.Initialize(projectRoot.string().c_str());

    AssetDatabase::ResolvedAsset resolvedAsset;
    ASSERT_TRUE(database.EnsureArtifact("Assets/relative.material", ResourceType::Material, resolvedAsset));
    EXPECT_TRUE(resolvedAsset.artifactReady);
    EXPECT_EQ(fs::path(resolvedAsset.artifactMainPath.CStr()).extension().string(), ".xcmat");
    EXPECT_TRUE(fs::exists(resolvedAsset.artifactMainPath.CStr()));

    database.Shutdown();
    fs::remove_all(projectRoot);
}

TEST(MaterialLoader, ResourceManagerLoadsProjectMaterialTextureAsLazyDependency) {
    namespace fs = std::filesystem;

    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();

    const fs::path projectRoot = fs::temp_directory_path() / "xc_material_asset_texture_test";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path materialPath = assetsDir / "textured.material";

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);
    fs::copy_file(
        GetMeshFixturePath("checker.bmp"),
        assetsDir / "checker.bmp",
        fs::copy_options::overwrite_existing);

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{\n";
        materialFile << "  \"renderQueue\": \"geometry\",\n";
        materialFile << "  \"textures\": {\n";
        materialFile << "    \"baseColorTexture\": \"checker.bmp\"\n";
        materialFile << "  }\n";
        materialFile << "}";
    }

    manager.SetResourceRoot(projectRoot.string().c_str());

    const auto materialHandle = manager.Load<Material>("Assets/textured.material");
    ASSERT_TRUE(materialHandle.IsValid());
    ASSERT_EQ(materialHandle->GetTextureBindingCount(), 1u);
    EXPECT_EQ(materialHandle->GetTextureBindingName(0), "baseColorTexture");
    EXPECT_EQ(
        fs::path(materialHandle->GetTextureBindingPath(0).CStr()).lexically_normal().generic_string(),
        (projectRoot / "Assets" / "checker.bmp").lexically_normal().generic_string());

    const ResourceHandle<Texture> initialTexture = materialHandle->GetTexture("baseColorTexture");
    EXPECT_FALSE(initialTexture.IsValid());
    EXPECT_GT(manager.GetAsyncPendingCount(), 0u);

    ASSERT_TRUE(PumpAsyncLoadsUntilIdle(manager));
    const ResourceHandle<Texture> loadedTexture = materialHandle->GetTexture("baseColorTexture");
    ASSERT_TRUE(loadedTexture.IsValid());
    EXPECT_EQ(loadedTexture->GetWidth(), 2u);
    EXPECT_EQ(loadedTexture->GetHeight(), 2u);

    manager.SetResourceRoot("");
    manager.Shutdown();
    fs::remove_all(projectRoot);
}

TEST(MaterialLoader, AssetDatabaseReimportsMaterialWhenTextureDependencyChanges) {
    namespace fs = std::filesystem;
    using namespace std::chrono_literals;

    const fs::path projectRoot = fs::temp_directory_path() / "xc_material_dependency_reimport_test";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path materialPath = assetsDir / "textured.material";

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);
    fs::copy_file(
        GetMeshFixturePath("checker.bmp"),
        assetsDir / "checker.bmp",
        fs::copy_options::overwrite_existing);

    {
        std::ofstream materialFile(materialPath);
        ASSERT_TRUE(materialFile.is_open());
        materialFile << "{\n";
        materialFile << "  \"baseColorTexture\": \"checker.bmp\"\n";
        materialFile << "}";
    }

    AssetDatabase database;
    database.Initialize(projectRoot.string().c_str());

    AssetDatabase::ResolvedAsset firstResolve;
    ASSERT_TRUE(database.EnsureArtifact("Assets/textured.material", ResourceType::Material, firstResolve));
    ASSERT_TRUE(firstResolve.artifactReady);
    const String firstArtifactPath = firstResolve.artifactMainPath;
    database.Shutdown();

    std::this_thread::sleep_for(50ms);
    FlipLastByte(assetsDir / "checker.bmp");

    database.Initialize(projectRoot.string().c_str());
    AssetDatabase::ResolvedAsset secondResolve;
    ASSERT_TRUE(database.EnsureArtifact("Assets/textured.material", ResourceType::Material, secondResolve));
    ASSERT_TRUE(secondResolve.artifactReady);
    EXPECT_NE(firstArtifactPath, secondResolve.artifactMainPath);
    EXPECT_TRUE(fs::exists(secondResolve.artifactMainPath.CStr()));
    database.Shutdown();

    fs::remove_all(projectRoot);
}

TEST(MaterialLoader, LoadMaterialArtifactDefersTexturePayloadUntilRequested) {
    namespace fs = std::filesystem;

    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();

    const fs::path projectRoot = fs::temp_directory_path() / "xc_material_xcmat_lazy_texture_test";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path libraryDir = projectRoot / "Library" / "Manual";
    const fs::path materialArtifactPath = libraryDir / "test.xcmat";

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);
    fs::create_directories(libraryDir);
    fs::copy_file(
        GetMeshFixturePath("checker.bmp"),
        assetsDir / "checker.bmp",
        fs::copy_options::overwrite_existing);

    {
        std::ofstream output(materialArtifactPath, std::ios::binary | std::ios::trunc);
        ASSERT_TRUE(output.is_open());

        MaterialArtifactFileHeader fileHeader;
        output.write(reinterpret_cast<const char*>(&fileHeader), sizeof(fileHeader));
        WriteArtifactString(output, "LazyMaterial");
        WriteArtifactString(output, "Assets/lazy.material");
        WriteArtifactString(output, "");
        WriteArtifactString(output, "");

        MaterialArtifactHeader header;
        header.renderQueue = static_cast<XCEngine::Core::int32>(MaterialRenderQueue::Geometry);
        header.textureBindingCount = 1;
        output.write(reinterpret_cast<const char*>(&header), sizeof(header));

        WriteArtifactString(output, "baseColorTexture");
        WriteArtifactString(output, "Assets/checker.bmp");
    }

    manager.SetResourceRoot(projectRoot.string().c_str());

    MaterialLoader loader;
    LoadResult result = loader.Load("Library/Manual/test.xcmat");
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    auto* material = static_cast<Material*>(result.resource);
    ASSERT_NE(material, nullptr);
    EXPECT_EQ(material->GetTextureBindingCount(), 1u);
    EXPECT_EQ(
        fs::path(material->GetTextureBindingPath(0).CStr()).lexically_normal().generic_string(),
        (projectRoot / "Assets" / "checker.bmp").lexically_normal().generic_string());

    const ResourceHandle<Texture> initialTexture = material->GetTexture("baseColorTexture");
    EXPECT_FALSE(initialTexture.IsValid());
    EXPECT_GT(manager.GetAsyncPendingCount(), 0u);

    ASSERT_TRUE(PumpAsyncLoadsUntilIdle(manager));
    const ResourceHandle<Texture> loadedTexture = material->GetTexture("baseColorTexture");
    ASSERT_TRUE(loadedTexture.IsValid());
    EXPECT_EQ(loadedTexture->GetWidth(), 2u);
    EXPECT_EQ(loadedTexture->GetHeight(), 2u);

    delete material;
    manager.SetResourceRoot("");
    manager.Shutdown();
    fs::remove_all(projectRoot);
}

} // namespace