#include <gtest/gtest.h>

#include <XCEngine/Core/Asset/AssetDatabase.h>
#include <XCEngine/Core/Asset/AssetRef.h>
#include <XCEngine/Core/Asset/ResourceManager.h>
#include <XCEngine/Resources/Volume/VolumeField.h>
#include <XCEngine/Resources/Volume/VolumeFieldLoader.h>

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

using namespace XCEngine::Resources;

namespace {

std::vector<unsigned char> MakeTestNanoVDBPayload() {
    return {
        0x4E, 0x56, 0x44, 0x42,
        0x10, 0x20, 0x30, 0x40,
        0x01, 0x03, 0x05, 0x07,
        0xAA, 0xBB, 0xCC, 0xDD
    };
}

void WriteBinaryFile(const std::filesystem::path& path, const std::vector<unsigned char>& bytes) {
    std::ofstream output(path, std::ios::binary | std::ios::trunc);
    output.write(reinterpret_cast<const char*>(bytes.data()), static_cast<std::streamsize>(bytes.size()));
}

TEST(VolumeFieldLoader, GetResourceType) {
    VolumeFieldLoader loader;
    EXPECT_EQ(loader.GetResourceType(), ResourceType::VolumeField);
}

TEST(VolumeFieldLoader, CanLoad) {
    VolumeFieldLoader loader;
    EXPECT_TRUE(loader.CanLoad("cloud.nvdb"));
    EXPECT_TRUE(loader.CanLoad("cloud.xcvol"));
    EXPECT_FALSE(loader.CanLoad("cloud.txt"));
}

TEST(VolumeFieldLoader, LoadInvalidPath) {
    VolumeFieldLoader loader;
    LoadResult result = loader.Load("invalid/path/cloud.nvdb");
    EXPECT_FALSE(result);
}

TEST(VolumeFieldLoader, LoadSourceNanoVDBBlob) {
    namespace fs = std::filesystem;

    const fs::path volumePath = fs::temp_directory_path() / "xc_volume_loader_source_test.nvdb";
    const std::vector<unsigned char> bytes = MakeTestNanoVDBPayload();
    WriteBinaryFile(volumePath, bytes);

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

    auto* volumeField = static_cast<VolumeField*>(result.resource);
    EXPECT_EQ(volumeField->GetStorageKind(), VolumeStorageKind::NanoVDB);
    EXPECT_EQ(volumeField->GetPayloadSize(), bytes.size());
    EXPECT_EQ(static_cast<const unsigned char*>(volumeField->GetPayloadData())[0], bytes[0]);

    delete volumeField;
    fs::remove(volumePath);
}

TEST(VolumeFieldLoader, AssetDatabaseCreatesVolumeArtifactAndReusesItWithoutReimport) {
    namespace fs = std::filesystem;
    using namespace std::chrono_literals;

    const fs::path projectRoot = fs::temp_directory_path() / "xc_volume_library_cache_test";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path volumePath = assetsDir / "cloud.nvdb";

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);
    WriteBinaryFile(volumePath, MakeTestNanoVDBPayload());

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

    AssetDatabase::ResolvedAsset firstResolve;
    ASSERT_TRUE(database.EnsureArtifact("Assets/cloud.nvdb", ResourceType::VolumeField, firstResolve));
    ASSERT_TRUE(firstResolve.exists);
    ASSERT_TRUE(firstResolve.artifactReady);
    EXPECT_TRUE(fs::exists(firstResolve.artifactMainPath.CStr()));
    EXPECT_EQ(fs::path(firstResolve.artifactMainPath.CStr()).extension().generic_string(), ".xcvol");

    VolumeFieldLoader loader;
    LoadResult artifactLoad = loader.Load(firstResolve.artifactMainPath);
    ASSERT_TRUE(artifactLoad);
    ASSERT_NE(artifactLoad.resource, nullptr);
    auto* artifactVolume = static_cast<VolumeField*>(artifactLoad.resource);
    EXPECT_EQ(artifactVolume->GetStorageKind(), VolumeStorageKind::NanoVDB);
    EXPECT_EQ(artifactVolume->GetPayloadSize(), MakeTestNanoVDBPayload().size());
    delete artifactVolume;

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

    AssetDatabase::ResolvedAsset secondResolve;
    ASSERT_TRUE(database.EnsureArtifact("Assets/cloud.nvdb", ResourceType::VolumeField, secondResolve));
    EXPECT_EQ(firstResolve.artifactMainPath, secondResolve.artifactMainPath);
    EXPECT_EQ(originalArtifactWriteTime, fs::last_write_time(secondResolve.artifactMainPath.CStr()));

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

TEST(VolumeFieldLoader, ResourceManagerLoadsVolumeByAssetRefFromProjectAssets) {
    namespace fs = std::filesystem;

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

    const fs::path projectRoot = fs::temp_directory_path() / "xc_volume_asset_ref_test";
    const fs::path assetsDir = projectRoot / "Assets";
    const fs::path volumePath = assetsDir / "cloud.nvdb";
    const std::vector<unsigned char> bytes = MakeTestNanoVDBPayload();

    fs::remove_all(projectRoot);
    fs::create_directories(assetsDir);
    WriteBinaryFile(volumePath, bytes);

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

    {
        const auto firstHandle = manager.Load<VolumeField>("Assets/cloud.nvdb");
        ASSERT_TRUE(firstHandle.IsValid());
        EXPECT_EQ(firstHandle->GetStorageKind(), VolumeStorageKind::NanoVDB);
        EXPECT_EQ(firstHandle->GetPayloadSize(), bytes.size());

        AssetRef assetRef;
        ASSERT_TRUE(manager.TryGetAssetRef("Assets/cloud.nvdb", ResourceType::VolumeField, assetRef));
        EXPECT_TRUE(assetRef.IsValid());

        manager.UnloadAll();

        const auto secondHandle = manager.Load<VolumeField>(assetRef);
        ASSERT_TRUE(secondHandle.IsValid());
        EXPECT_EQ(secondHandle->GetStorageKind(), VolumeStorageKind::NanoVDB);
        EXPECT_EQ(secondHandle->GetPayloadSize(), bytes.size());
    }

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

} // namespace