#include <XCEngine/Resources/Model/ModelArtifactIO.h>

#include <XCEngine/Core/Asset/ArtifactFormats.h>
#include <XCEngine/Core/Asset/ResourceManager.h>
#include <XCEngine/Resources/Model/Model.h>

#include <cstring>
#include <filesystem>
#include <fstream>
#include <string>

namespace XCEngine {
namespace Resources {

namespace {

Containers::String GetResourceNameFromPath(const Containers::String& path) {
    const std::filesystem::path filePath(path.CStr());
    const std::string fileName = filePath.filename().string();
    if (!fileName.empty()) {
        return Containers::String(fileName.c_str());
    }
    return path;
}

std::filesystem::path ResolveArtifactPath(const Containers::String& path) {
    std::filesystem::path resolvedPath(path.CStr());
    if (!resolvedPath.is_absolute() && !std::filesystem::exists(resolvedPath)) {
        const Containers::String& resourceRoot = ResourceManager::Get().GetResourceRoot();
        if (!resourceRoot.Empty()) {
            resolvedPath = std::filesystem::path(resourceRoot.CStr()) / resolvedPath;
        }
    }

    return resolvedPath.lexically_normal();
}

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

Containers::String ReadString(std::ifstream& stream) {
    Core::uint32 length = 0;
    stream.read(reinterpret_cast<char*>(&length), sizeof(length));
    if (!stream || length == 0) {
        return Containers::String();
    }

    std::string buffer(length, '\0');
    stream.read(buffer.data(), length);
    if (!stream) {
        return Containers::String();
    }

    return Containers::String(buffer.c_str());
}

LoadResult CreateOwnedModelResource(const Containers::String& path,
                                    const ModelArtifactHeader& header,
                                    Containers::Array<ModelNode>&& nodes,
                                    Containers::Array<ModelMeshBinding>&& meshBindings,
                                    Containers::Array<ModelMaterialBinding>&& materialBindings) {
    auto* model = new Model();

    IResource::ConstructParams params;
    params.name = GetResourceNameFromPath(path);
    params.path = path;
    params.guid = ResourceGUID::Generate(path);
    params.memorySize = 0;
    model->Initialize(params);

    if (header.rootNodeIndex != kInvalidModelNodeIndex) {
        model->SetRootNodeIndex(header.rootNodeIndex);
    }

    for (const ModelNode& node : nodes) {
        model->AddNode(node);
    }

    for (const ModelMeshBinding& binding : meshBindings) {
        model->AddMeshBinding(binding);
    }

    for (const ModelMaterialBinding& binding : materialBindings) {
        model->AddMaterialBinding(binding);
    }

    return LoadResult(model);
}

} // namespace

bool WriteModelArtifactFile(const Containers::String& artifactPath,
                            const Model& model,
                            Containers::String* outErrorMessage) {
    const std::filesystem::path resolvedPath = ResolveArtifactPath(artifactPath);
    std::error_code ec;
    const std::filesystem::path parentPath = resolvedPath.parent_path();
    if (!parentPath.empty()) {
        std::filesystem::create_directories(parentPath, ec);
        if (ec) {
            if (outErrorMessage != nullptr) {
                *outErrorMessage =
                    Containers::String("Failed to create model artifact directory: ") +
                    Containers::String(parentPath.generic_string().c_str());
            }
            return false;
        }
    }

    std::ofstream output(resolvedPath, std::ios::binary | std::ios::trunc);
    if (!output.is_open()) {
        if (outErrorMessage != nullptr) {
            *outErrorMessage = Containers::String("Failed to open model artifact for write: ") + artifactPath;
        }
        return false;
    }

    ModelArtifactFileHeader fileHeader;
    output.write(reinterpret_cast<const char*>(&fileHeader), sizeof(fileHeader));

    ModelArtifactHeader header;
    header.nodeCount = static_cast<Core::uint32>(model.GetNodes().Size());
    header.meshBindingCount = static_cast<Core::uint32>(model.GetMeshBindings().Size());
    header.materialBindingCount = static_cast<Core::uint32>(model.GetMaterialBindings().Size());
    header.rootNodeIndex = model.GetRootNodeIndex();
    output.write(reinterpret_cast<const char*>(&header), sizeof(header));

    for (const ModelNode& node : model.GetNodes()) {
        WriteString(output, node.name);

        ModelNodeArtifactHeader nodeHeader;
        nodeHeader.parentIndex = node.parentIndex;
        nodeHeader.meshBindingStart = node.meshBindingStart;
        nodeHeader.meshBindingCount = node.meshBindingCount;
        nodeHeader.localPosition = node.localPosition;
        nodeHeader.localRotation = node.localRotation;
        nodeHeader.localScale = node.localScale;
        output.write(reinterpret_cast<const char*>(&nodeHeader), sizeof(nodeHeader));
    }

    for (const ModelMeshBinding& binding : model.GetMeshBindings()) {
        ModelMeshBindingArtifact bindingArtifact;
        bindingArtifact.meshLocalID = binding.meshLocalID;
        bindingArtifact.materialBindingStart = binding.materialBindingStart;
        bindingArtifact.materialBindingCount = binding.materialBindingCount;
        output.write(reinterpret_cast<const char*>(&bindingArtifact), sizeof(bindingArtifact));
    }

    for (const ModelMaterialBinding& binding : model.GetMaterialBindings()) {
        ModelMaterialBindingArtifact bindingArtifact;
        bindingArtifact.slotIndex = binding.slotIndex;
        bindingArtifact.materialLocalID = binding.materialLocalID;
        output.write(reinterpret_cast<const char*>(&bindingArtifact), sizeof(bindingArtifact));
    }

    if (!output && outErrorMessage != nullptr) {
        *outErrorMessage = Containers::String("Failed to write model artifact: ") + artifactPath;
    }

    return static_cast<bool>(output);
}

LoadResult LoadModelArtifact(const Containers::String& path) {
    const std::filesystem::path resolvedPath = ResolveArtifactPath(path);

    std::ifstream input(resolvedPath, std::ios::binary);
    if (!input.is_open()) {
        return LoadResult(Containers::String("Failed to read model artifact: ") + path);
    }

    ModelArtifactFileHeader fileHeader;
    input.read(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));
    if (!input) {
        return LoadResult(Containers::String("Failed to parse model artifact file header: ") + path);
    }

    const bool validFileHeader =
        std::memcmp(fileHeader.magic, "XCMOD01", 7) == 0 &&
        fileHeader.schemaVersion == kModelArtifactSchemaVersion;
    if (!validFileHeader) {
        return LoadResult(Containers::String("Invalid model artifact file header: ") + path);
    }

    ModelArtifactHeader header;
    input.read(reinterpret_cast<char*>(&header), sizeof(header));
    if (!input) {
        return LoadResult(Containers::String("Failed to parse model artifact header: ") + path);
    }

    if (header.rootNodeIndex != kInvalidModelNodeIndex &&
        header.rootNodeIndex >= header.nodeCount) {
        return LoadResult(Containers::String("Invalid model artifact root node index: ") + path);
    }

    Containers::Array<ModelNode> nodes;
    nodes.Reserve(header.nodeCount);
    for (Core::uint32 index = 0; index < header.nodeCount; ++index) {
        ModelNode node;
        node.name = ReadString(input);

        ModelNodeArtifactHeader nodeHeader;
        input.read(reinterpret_cast<char*>(&nodeHeader), sizeof(nodeHeader));
        if (!input) {
            return LoadResult(Containers::String("Failed to read model node artifact: ") + path);
        }

        node.parentIndex = nodeHeader.parentIndex;
        node.meshBindingStart = nodeHeader.meshBindingStart;
        node.meshBindingCount = nodeHeader.meshBindingCount;
        node.localPosition = nodeHeader.localPosition;
        node.localRotation = nodeHeader.localRotation;
        node.localScale = nodeHeader.localScale;
        nodes.PushBack(std::move(node));
    }

    Containers::Array<ModelMeshBinding> meshBindings;
    meshBindings.Reserve(header.meshBindingCount);
    for (Core::uint32 index = 0; index < header.meshBindingCount; ++index) {
        ModelMeshBindingArtifact bindingArtifact;
        input.read(reinterpret_cast<char*>(&bindingArtifact), sizeof(bindingArtifact));
        if (!input) {
            return LoadResult(Containers::String("Failed to read model mesh binding artifact: ") + path);
        }

        ModelMeshBinding binding;
        binding.meshLocalID = bindingArtifact.meshLocalID;
        binding.materialBindingStart = bindingArtifact.materialBindingStart;
        binding.materialBindingCount = bindingArtifact.materialBindingCount;
        meshBindings.PushBack(binding);
    }

    Containers::Array<ModelMaterialBinding> materialBindings;
    materialBindings.Reserve(header.materialBindingCount);
    for (Core::uint32 index = 0; index < header.materialBindingCount; ++index) {
        ModelMaterialBindingArtifact bindingArtifact;
        input.read(reinterpret_cast<char*>(&bindingArtifact), sizeof(bindingArtifact));
        if (!input) {
            return LoadResult(Containers::String("Failed to read model material binding artifact: ") + path);
        }

        ModelMaterialBinding binding;
        binding.slotIndex = bindingArtifact.slotIndex;
        binding.materialLocalID = bindingArtifact.materialLocalID;
        materialBindings.PushBack(binding);
    }

    return CreateOwnedModelResource(
        path,
        header,
        std::move(nodes),
        std::move(meshBindings),
        std::move(materialBindings));
}

} // namespace Resources
} // namespace XCEngine