#include "Components/MeshRendererComponent.h"

#include "Components/GameObject.h"
#include "Core/Asset/ResourceManager.h"
#include "Debug/Logger.h"

#include <sstream>

namespace XCEngine {
namespace Components {

namespace {

std::string ToStdString(const Containers::String& value) {
    return std::string(value.CStr());
}

bool ShouldTraceMaterialPath(const std::string& path) {
    return path.rfind("builtin://", 0) == 0 ||
           path.find("backpack") != std::string::npos ||
           path.find("New Material.mat") != std::string::npos;
}

std::string EncodeAssetRef(const Resources::AssetRef& assetRef) {
    if (!assetRef.IsValid()) {
        return std::string();
    }

    return ToStdString(assetRef.assetGuid.ToString()) + "," +
           std::to_string(assetRef.localID) + "," +
           std::to_string(static_cast<int>(assetRef.resourceType));
}

bool TryDecodeAssetRef(const std::string& value, Resources::AssetRef& outRef) {
    const size_t firstComma = value.find(',');
    const size_t secondComma = firstComma == std::string::npos ? std::string::npos : value.find(',', firstComma + 1);
    if (firstComma == std::string::npos || secondComma == std::string::npos) {
        return false;
    }

    outRef.assetGuid = Resources::AssetGUID::ParseOrDefault(Containers::String(value.substr(0, firstComma).c_str()));
    outRef.localID = static_cast<Resources::LocalID>(std::stoull(value.substr(firstComma + 1, secondComma - firstComma - 1)));
    outRef.resourceType = static_cast<Resources::ResourceType>(std::stoi(value.substr(secondComma + 1)));
    return outRef.IsValid();
}

std::vector<std::string> SplitMaterialPaths(const std::string& value) {
    std::vector<std::string> paths;
    if (value.empty()) {
        return paths;
    }

    size_t start = 0;
    while (true) {
        const size_t separator = value.find('|', start);
        if (separator == std::string::npos) {
            paths.push_back(value.substr(start));
            break;
        }

        paths.push_back(value.substr(start, separator - start));
        start = separator + 1;
    }

    return paths;
}

std::vector<Resources::AssetRef> SplitMaterialRefs(const std::string& value) {
    std::vector<Resources::AssetRef> refs;
    if (value.empty()) {
        return refs;
    }

    size_t start = 0;
    while (true) {
        const size_t separator = value.find('|', start);
        const std::string token = separator == std::string::npos
            ? value.substr(start)
            : value.substr(start, separator - start);

        Resources::AssetRef ref;
        TryDecodeAssetRef(token, ref);
        refs.push_back(ref);

        if (separator == std::string::npos) {
            break;
        }
        start = separator + 1;
    }

    return refs;
}

std::string JoinMaterialPaths(const std::vector<std::string>& values) {
    std::ostringstream stream;
    for (size_t index = 0; index < values.size(); ++index) {
        if (index > 0) {
            stream << "|";
        }
        stream << values[index];
    }
    return stream.str();
}

std::string JoinMaterialRefs(const std::vector<Resources::AssetRef>& values) {
    std::ostringstream stream;
    for (size_t index = 0; index < values.size(); ++index) {
        if (index > 0) {
            stream << "|";
        }
        stream << EncodeAssetRef(values[index]);
    }
    return stream.str();
}

bool ShouldTraceAnyMaterialPath(const std::vector<std::string>& values) {
    for (const std::string& value : values) {
        if (ShouldTraceMaterialPath(value)) {
            return true;
        }
    }
    return false;
}

std::string DescribeOwner(const MeshRendererComponent& component) {
    const GameObject* owner = component.GetGameObject();
    if (owner == nullptr) {
        return "<no-owner>";
    }

    return std::string("id=") + std::to_string(owner->GetID()) + ",name=" + owner->GetName();
}

void TraceMeshRenderer(const MeshRendererComponent& component, const std::string& message) {
    Debug::Logger::Get().Info(
        Debug::LogCategory::FileSystem,
        Containers::String(("[MeshRenderer] owner={" + DescribeOwner(component) + "} " + message).c_str()));
}

} // namespace

struct MeshRendererComponent::PendingMaterialLoadState {
    Resources::LoadResult result;
    bool completed = false;
};

Resources::Material* MeshRendererComponent::GetMaterial(size_t index) const {
    const_cast<MeshRendererComponent*>(this)->ResolvePendingMaterials();
    return index < m_materials.size() ? m_materials[index].Get() : nullptr;
}

const Resources::ResourceHandle<Resources::Material>& MeshRendererComponent::GetMaterialHandle(size_t index) const {
    const_cast<MeshRendererComponent*>(this)->ResolvePendingMaterials();
    static const Resources::ResourceHandle<Resources::Material> kNullHandle;
    return index < m_materials.size() ? m_materials[index] : kNullHandle;
}

const std::string& MeshRendererComponent::GetMaterialPath(size_t index) const {
    static const std::string kEmptyPath;
    return index < m_materialPaths.size() ? m_materialPaths[index] : kEmptyPath;
}

void MeshRendererComponent::SetMaterialPath(size_t index, const std::string& materialPath) {
    EnsureMaterialSlot(index);
    m_pendingMaterialLoads[index].reset();
    m_materialPaths[index] = materialPath;
    if (materialPath.empty()) {
        m_materials[index].Reset();
        m_materialRefs[index].Reset();
        return;
    }

    m_materials[index] = Resources::ResourceManager::Get().Load<Resources::Material>(materialPath.c_str());
    if (!Resources::ResourceManager::Get().TryGetAssetRef(materialPath.c_str(), Resources::ResourceType::Material, m_materialRefs[index])) {
        m_materialRefs[index].Reset();
    }

    if (ShouldTraceMaterialPath(materialPath)) {
        TraceMeshRenderer(
            *this,
            std::string("SetMaterialPath slot=") + std::to_string(index) +
            " path=" + materialPath +
            " ref=" + EncodeAssetRef(m_materialRefs[index]) +
            " loaded=" + (m_materials[index].Get() != nullptr ? "1" : "0"));
    }
}

void MeshRendererComponent::SetMaterial(size_t index, const Resources::ResourceHandle<Resources::Material>& material) {
    EnsureMaterialSlot(index);
    m_pendingMaterialLoads[index].reset();
    m_materials[index] = material;
    m_materialPaths[index] = MaterialPathFromHandle(material);
    if (m_materialPaths[index].empty() ||
        !Resources::ResourceManager::Get().TryGetAssetRef(m_materialPaths[index].c_str(), Resources::ResourceType::Material, m_materialRefs[index])) {
        m_materialRefs[index].Reset();
    }
}

void MeshRendererComponent::SetMaterial(size_t index, Resources::Material* material) {
    SetMaterial(index, Resources::ResourceHandle<Resources::Material>(material));
}

void MeshRendererComponent::SetMaterials(const std::vector<Resources::ResourceHandle<Resources::Material>>& materials) {
    m_materials = materials;
    m_materialPaths.resize(materials.size());
    m_materialRefs.resize(materials.size());
    m_pendingMaterialLoads.clear();
    m_pendingMaterialLoads.resize(materials.size());
    for (size_t i = 0; i < materials.size(); ++i) {
        m_materialPaths[i] = MaterialPathFromHandle(materials[i]);
        if (m_materialPaths[i].empty() ||
            !Resources::ResourceManager::Get().TryGetAssetRef(m_materialPaths[i].c_str(), Resources::ResourceType::Material, m_materialRefs[i])) {
            m_materialRefs[i].Reset();
        }
    }
}

void MeshRendererComponent::ClearMaterials() {
    m_materials.clear();
    m_materialPaths.clear();
    m_materialRefs.clear();
    m_pendingMaterialLoads.clear();
}

void MeshRendererComponent::Serialize(std::ostream& os) const {
    os << "materials=";
    for (size_t i = 0; i < m_materialPaths.size(); ++i) {
        if (i > 0) {
            os << "|";
        }
        os << m_materialPaths[i];
    }
    os << ";";
    os << "materialRefs=";
    for (size_t i = 0; i < m_materialRefs.size(); ++i) {
        if (i > 0) {
            os << "|";
        }
        os << EncodeAssetRef(m_materialRefs[i]);
    }
    os << ";";
    os << "castShadows=" << (m_castShadows ? 1 : 0) << ";";
    os << "receiveShadows=" << (m_receiveShadows ? 1 : 0) << ";";
    os << "renderLayer=" << m_renderLayer << ";";
}

void MeshRendererComponent::Deserialize(std::istream& is) {
    ClearMaterials();
    m_castShadows = true;
    m_receiveShadows = true;
    m_renderLayer = 0;

    std::string token;
    std::vector<Resources::AssetRef> pendingMaterialRefs;
    while (std::getline(is, token, ';')) {
        if (token.empty()) {
            continue;
        }

        const size_t eqPos = token.find('=');
        if (eqPos == std::string::npos) {
            continue;
        }

        const std::string key = token.substr(0, eqPos);
        const std::string value = token.substr(eqPos + 1);

        if (key == "materials") {
            m_materialPaths = SplitMaterialPaths(value);
            m_materials.resize(m_materialPaths.size());
            m_materialRefs.resize(m_materialPaths.size());
            m_pendingMaterialLoads.resize(m_materialPaths.size());
        } else if (key == "materialRefs") {
            pendingMaterialRefs = SplitMaterialRefs(value);
        } else if (key == "castShadows") {
            m_castShadows = (std::stoi(value) != 0);
        } else if (key == "receiveShadows") {
            m_receiveShadows = (std::stoi(value) != 0);
        } else if (key == "renderLayer") {
            m_renderLayer = static_cast<uint32_t>(std::stoul(value));
        }
    }

    if (pendingMaterialRefs.size() > m_materialPaths.size()) {
        m_materialPaths.resize(pendingMaterialRefs.size());
        m_materials.resize(pendingMaterialRefs.size());
        m_materialRefs.resize(pendingMaterialRefs.size());
        m_pendingMaterialLoads.resize(pendingMaterialRefs.size());
    }

    if (ShouldTraceAnyMaterialPath(m_materialPaths)) {
        TraceMeshRenderer(
            *this,
            std::string("Deserialize paths=") + JoinMaterialPaths(m_materialPaths) +
            " refs=" + JoinMaterialRefs(pendingMaterialRefs) +
            " deferred=" + (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled() ? "1" : "0"));
    }

    for (size_t i = 0; i < m_materialPaths.size(); ++i) {
        bool restoredOrQueued = false;
        if (i < pendingMaterialRefs.size() && pendingMaterialRefs[i].IsValid()) {
            m_materialRefs[i] = pendingMaterialRefs[i];
            if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
                Containers::String resolvedPath;
                if (Resources::ResourceManager::Get().TryResolveAssetPath(pendingMaterialRefs[i], resolvedPath)) {
                    m_materialPaths[i] = ToStdString(resolvedPath);
                    if (ShouldTraceMaterialPath(m_materialPaths[i])) {
                        TraceMeshRenderer(
                            *this,
                            std::string("Resolved materialRef slot=") + std::to_string(i) +
                            " path=" + m_materialPaths[i]);
                    }
                    BeginAsyncMaterialLoad(i, m_materialPaths[i]);
                    restoredOrQueued = true;
                }
            }

            if (!restoredOrQueued) {
                m_materials[i] = Resources::ResourceManager::Get().Load<Resources::Material>(pendingMaterialRefs[i]);
            }
            if (m_materials[i].Get() != nullptr) {
                m_materialPaths[i] = MaterialPathFromHandle(m_materials[i]);
                restoredOrQueued = true;
            }

            if (restoredOrQueued) {
                continue;
            }
        }

        if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
            if (!m_materialPaths[i].empty()) {
                if (!m_materialRefs[i].IsValid() &&
                    !Resources::ResourceManager::Get().TryGetAssetRef(m_materialPaths[i].c_str(),
                                                                      Resources::ResourceType::Material,
                                                                      m_materialRefs[i])) {
                    m_materialRefs[i].Reset();
                }
                BeginAsyncMaterialLoad(i, m_materialPaths[i]);
            }
            continue;
        }

        SetMaterialPath(i, m_materialPaths[i]);
    }
}

void MeshRendererComponent::BeginAsyncMaterialLoad(size_t index, const std::string& materialPath) {
    EnsureMaterialSlot(index);
    if (materialPath.empty()) {
        m_pendingMaterialLoads[index].reset();
        m_materials[index].Reset();
        return;
    }

    m_materials[index].Reset();
    m_pendingMaterialLoads[index] = std::make_shared<PendingMaterialLoadState>();
    if (ShouldTraceMaterialPath(materialPath)) {
        TraceMeshRenderer(
            *this,
            std::string("BeginAsyncMaterialLoad slot=") + std::to_string(index) +
            " path=" + materialPath);
    }
    std::weak_ptr<PendingMaterialLoadState> weakState = m_pendingMaterialLoads[index];
    Resources::ResourceManager::Get().LoadAsync(materialPath.c_str(),
                                                Resources::ResourceType::Material,
                                                [weakState](Resources::LoadResult result) {
        if (std::shared_ptr<PendingMaterialLoadState> state = weakState.lock()) {
            state->result = std::move(result);
            state->completed = true;
        }
    });
}

void MeshRendererComponent::ResolvePendingMaterials() {
    for (size_t index = 0; index < m_pendingMaterialLoads.size(); ++index) {
        if (!m_pendingMaterialLoads[index] || !m_pendingMaterialLoads[index]->completed) {
            continue;
        }

        std::shared_ptr<PendingMaterialLoadState> completedLoad = std::move(m_pendingMaterialLoads[index]);
        m_pendingMaterialLoads[index].reset();

        if (!completedLoad->result || completedLoad->result.resource == nullptr) {
            if (ShouldTraceMaterialPath(m_materialPaths[index])) {
                TraceMeshRenderer(
                    *this,
                    std::string("ResolvePendingMaterial failed slot=") + std::to_string(index) +
                    " path=" + m_materialPaths[index] +
                    " error=" + ToStdString(completedLoad->result.errorMessage));
            }
            continue;
        }

        m_materials[index] = Resources::ResourceHandle<Resources::Material>(
            static_cast<Resources::Material*>(completedLoad->result.resource));
        if (m_materials[index].Get() == nullptr) {
            continue;
        }

        m_materialPaths[index] = MaterialPathFromHandle(m_materials[index]);
        if (!Resources::ResourceManager::Get().TryGetAssetRef(m_materialPaths[index].c_str(),
                                                              Resources::ResourceType::Material,
                                                              m_materialRefs[index])) {
            m_materialRefs[index].Reset();
        }

        if (ShouldTraceMaterialPath(m_materialPaths[index])) {
            TraceMeshRenderer(
                *this,
                std::string("ResolvePendingMaterial success slot=") + std::to_string(index) +
                " path=" + m_materialPaths[index] +
                " ref=" + EncodeAssetRef(m_materialRefs[index]));
        }
    }
}

void MeshRendererComponent::EnsureMaterialSlot(size_t index) {
    if (index >= m_materials.size()) {
        m_materials.resize(index + 1);
    }
    if (index >= m_materialPaths.size()) {
        m_materialPaths.resize(index + 1);
    }
    if (index >= m_materialRefs.size()) {
        m_materialRefs.resize(index + 1);
    }
    if (index >= m_pendingMaterialLoads.size()) {
        m_pendingMaterialLoads.resize(index + 1);
    }
}

std::string MeshRendererComponent::MaterialPathFromHandle(const Resources::ResourceHandle<Resources::Material>& material) {
    return material.Get() != nullptr ? ToStdString(material->GetPath()) : std::string();
}

} // namespace Components
} // namespace XCEngine