#include <gtest/gtest.h>
#include <XCEngine/Core/Asset/AssetDatabase.h>
#include <XCEngine/Core/Asset/ResourceManager.h>
#include <XCEngine/Resources/Mesh/MeshLoader.h>
#include <XCEngine/Resources/Mesh/MeshImportSettings.h>
#include <XCEngine/Resources/Material/Material.h>
#include <XCEngine/Resources/Texture/Texture.h>
#include <XCEngine/Core/Asset/ResourceTypes.h>
#include <XCEngine/Core/Containers/Array.h>

#include <chrono>
#include <filesystem>
#include <thread>

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();
}

TEST(MeshLoader, GetResourceType) {
    MeshLoader loader;
    EXPECT_EQ(loader.GetResourceType(), ResourceType::Mesh);
}

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

TEST(MeshLoader, CanLoad) {
    MeshLoader loader;
    EXPECT_TRUE(loader.CanLoad("test.obj"));
    EXPECT_TRUE(loader.CanLoad("test.fbx"));
    EXPECT_TRUE(loader.CanLoad("test.gltf"));
    EXPECT_TRUE(loader.CanLoad("test.OBJ"));
    EXPECT_FALSE(loader.CanLoad("test.txt"));
    EXPECT_FALSE(loader.CanLoad("test.png"));
}

TEST(MeshLoader, LoadInvalidPath) {
    MeshLoader loader;
    LoadResult result = loader.Load("invalid/path/mesh.obj");
    EXPECT_FALSE(result);
}

TEST(MeshLoader, ResourceManagerRegistersMeshAndTextureLoaders) {
    ResourceManager& manager = ResourceManager::Get();
    manager.Initialize();

    EXPECT_NE(manager.GetLoader(ResourceType::Mesh), nullptr);
    EXPECT_NE(manager.GetLoader(ResourceType::Texture), nullptr);

    manager.Shutdown();
}

TEST(MeshLoader, LoadValidObjMesh) {
    MeshLoader loader;
    const std::string path = GetMeshFixturePath("triangle.obj");

    LoadResult result = loader.Load(path.c_str());
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    auto* mesh = static_cast<Mesh*>(result.resource);
    EXPECT_EQ(mesh->GetVertexCount(), 3u);
    EXPECT_EQ(mesh->GetIndexCount(), 3u);
    EXPECT_EQ(mesh->GetVertexStride(), sizeof(StaticMeshVertex));
    EXPECT_FALSE(mesh->IsUse32BitIndex());
    ASSERT_EQ(mesh->GetSections().Size(), 1u);
    EXPECT_EQ(mesh->GetSections()[0].vertexCount, 3u);
    EXPECT_EQ(mesh->GetSections()[0].indexCount, 3u);
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Position));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Normal));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::UV0));
    EXPECT_EQ(mesh->GetBounds().GetMin(), XCEngine::Math::Vector3(0.0f, 0.0f, -1.0f));
    EXPECT_EQ(mesh->GetBounds().GetMax(), XCEngine::Math::Vector3(1.0f, 1.0f, -1.0f));
    EXPECT_EQ(mesh->GetSections()[0].bounds.GetMin(), XCEngine::Math::Vector3(0.0f, 0.0f, -1.0f));
    EXPECT_EQ(mesh->GetSections()[0].bounds.GetMax(), XCEngine::Math::Vector3(1.0f, 1.0f, -1.0f));

    const auto* vertices = static_cast<const StaticMeshVertex*>(mesh->GetVertexData());
    ASSERT_NE(vertices, nullptr);
    EXPECT_FLOAT_EQ(vertices[0].position.x, 0.0f);
    EXPECT_FLOAT_EQ(vertices[0].position.y, 0.0f);
    EXPECT_FLOAT_EQ(vertices[0].position.z, -1.0f);
    EXPECT_FLOAT_EQ(vertices[0].normal.z, -1.0f);
    EXPECT_FLOAT_EQ(vertices[1].uv0.x, 1.0f);
    EXPECT_FLOAT_EQ(vertices[2].uv0.y, 1.0f);

    delete mesh;
}

TEST(MeshLoader, GeneratesNormalsAndTangentsWhenRequested) {
    MeshLoader loader;
    MeshImportSettings settings;
    settings.AddImportFlag(MeshImportFlags::GenerateNormals);
    settings.AddImportFlag(MeshImportFlags::GenerateTangents);

    const std::string path = GetMeshFixturePath("triangle_no_normals.obj");
    LoadResult result = loader.Load(path.c_str(), &settings);
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    auto* mesh = static_cast<Mesh*>(result.resource);
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Normal));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Tangent));
    EXPECT_TRUE(HasVertexAttribute(mesh->GetVertexAttributes(), VertexAttribute::Bitangent));

    const auto* vertices = static_cast<const StaticMeshVertex*>(mesh->GetVertexData());
    ASSERT_NE(vertices, nullptr);
    EXPECT_GT(vertices[0].normal.Magnitude(), 0.0f);
    EXPECT_GT(vertices[0].tangent.Magnitude(), 0.0f);
    EXPECT_GT(vertices[0].bitangent.Magnitude(), 0.0f);

    delete mesh;
}

TEST(MeshLoader, ImportsMaterialTexturesFromObj) {
    MeshLoader loader;
    const std::string path = GetMeshFixturePath("textured_triangle.obj");

    LoadResult result = loader.Load(path.c_str());
    ASSERT_TRUE(result);
    ASSERT_NE(result.resource, nullptr);

    auto* mesh = static_cast<Mesh*>(result.resource);
    ASSERT_EQ(mesh->GetSections().Size(), 1u);
    ASSERT_GE(mesh->GetMaterials().Size(), 1u);
    EXPECT_LT(mesh->GetSections()[0].materialID, mesh->GetMaterials().Size());

    Material* material = mesh->GetMaterial(mesh->GetSections()[0].materialID);
    ASSERT_NE(material, nullptr);
    EXPECT_TRUE(material->HasProperty("baseColorTexture"));
    EXPECT_EQ(material->GetTextureBindingCount(), 1u);

    ResourceHandle<Texture> diffuseTexture = material->GetTexture("baseColorTexture");
    ASSERT_TRUE(diffuseTexture.IsValid());
    EXPECT_EQ(diffuseTexture->GetWidth(), 2u);
    EXPECT_EQ(diffuseTexture->GetHeight(), 2u);
    EXPECT_EQ(diffuseTexture->GetPixelDataSize(), 16u);
    EXPECT_EQ(mesh->GetTextures().Size(), 1u);

    delete mesh;
}

TEST(MeshLoader, AssetDatabaseCreatesModelArtifactAndReusesItWithoutReimport) {
    namespace fs = std::filesystem;
    using namespace std::chrono_literals;

    const fs::path projectRoot = fs::temp_directory_path() / "xc_mesh_library_cache_test";
    const fs::path assetsDir = projectRoot / "Assets";

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

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

    AssetDatabase::ResolvedAsset firstResolve;
    ASSERT_TRUE(database.EnsureArtifact("Assets/textured_triangle.obj", ResourceType::Mesh, firstResolve));
    ASSERT_TRUE(firstResolve.exists);
    ASSERT_TRUE(firstResolve.artifactReady);
    EXPECT_TRUE(fs::exists(projectRoot / "Assets" / "textured_triangle.obj.meta"));
    EXPECT_TRUE(fs::exists(projectRoot / "Library" / "SourceAssetDB" / "assets.db"));
    EXPECT_TRUE(fs::exists(projectRoot / "Library" / "ArtifactDB" / "artifacts.db"));
    EXPECT_TRUE(fs::exists(firstResolve.artifactMainPath.CStr()));
    EXPECT_TRUE(fs::exists((fs::path(firstResolve.artifactDirectory.CStr()) / "texture_0.xctex")));

    AssetRef assetRef;
    ASSERT_TRUE(database.TryGetAssetRef("Assets/textured_triangle.obj", ResourceType::Mesh, assetRef));
    EXPECT_TRUE(assetRef.IsValid());

    const auto originalArtifactWriteTime = fs::last_write_time(firstResolve.artifactMainPath.CStr());
    std::this_thread::sleep_for(50ms);

    AssetDatabase::ResolvedAsset secondResolve;
    ASSERT_TRUE(database.EnsureArtifact("Assets/textured_triangle.obj", ResourceType::Mesh, secondResolve));
    EXPECT_EQ(firstResolve.artifactMainPath, secondResolve.artifactMainPath);
    EXPECT_EQ(originalArtifactWriteTime, fs::last_write_time(secondResolve.artifactMainPath.CStr()));

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

TEST(MeshLoader, ResourceManagerLoadsModelByAssetRefFromProjectAssets) {
    namespace fs = std::filesystem;

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

    const fs::path projectRoot = fs::temp_directory_path() / "xc_mesh_asset_ref_test";
    const fs::path assetsDir = projectRoot / "Assets";

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

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

    const auto firstHandle = manager.Load<Mesh>("Assets/textured_triangle.obj");
    ASSERT_TRUE(firstHandle.IsValid());
    EXPECT_EQ(firstHandle->GetVertexCount(), 3u);
    EXPECT_EQ(firstHandle->GetIndexCount(), 3u);
    EXPECT_GE(firstHandle->GetMaterials().Size(), 1u);
    EXPECT_EQ(firstHandle->GetTextures().Size(), 1u);
    const auto initialMaterialCount = firstHandle->GetMaterials().Size();

    AssetRef assetRef;
    ASSERT_TRUE(manager.TryGetAssetRef("Assets/textured_triangle.obj", ResourceType::Mesh, assetRef));
    EXPECT_TRUE(assetRef.IsValid());

    manager.UnloadAll();

    const auto secondHandle = manager.Load<Mesh>(assetRef);
    ASSERT_TRUE(secondHandle.IsValid());
    EXPECT_EQ(secondHandle->GetPath(), "Assets/textured_triangle.obj");
    EXPECT_EQ(secondHandle->GetVertexCount(), 3u);
    EXPECT_EQ(secondHandle->GetIndexCount(), 3u);
    EXPECT_EQ(secondHandle->GetMaterials().Size(), initialMaterialCount);
    EXPECT_EQ(secondHandle->GetTextures().Size(), 1u);

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

} // namespace