#include "Components/VolumeRendererComponent.h"

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

#include <chrono>

namespace XCEngine {
namespace Components {

namespace {

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

bool HasVirtualPathScheme(const std::string& path) {
    return path.find("://") != 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;
    }

    const Containers::String guidText(value.substr(0, firstComma).c_str());
    outRef.assetGuid = Resources::AssetGUID::ParseOrDefault(guidText);
    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::string VolumeFieldPathFromHandle(const Resources::ResourceHandle<Resources::VolumeField>& volumeField) {
    return volumeField.Get() != nullptr ? ToStdString(volumeField->GetPath()) : std::string();
}

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

uint64_t GetVolumeTraceSteadyMs() {
    using Clock = std::chrono::steady_clock;
    static const Clock::time_point s_start = Clock::now();
    return static_cast<uint64_t>(std::chrono::duration_cast<std::chrono::milliseconds>(
        Clock::now() - s_start).count());
}

void LogVolumeTraceFileSystem(const std::string& message) {
    Containers::String entry("[VolumeTrace] ");
    entry += message.c_str();
    Debug::Logger::Get().Info(Debug::LogCategory::FileSystem, entry);
}

} // namespace

struct VolumeRendererComponent::PendingVolumeLoadState {
    Resources::LoadResult result;
    uint64_t requestedAtMs = 0u;
    bool completed = false;
};

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

Resources::VolumeField* VolumeRendererComponent::GetVolumeField() const {
    const_cast<VolumeRendererComponent*>(this)->EnsureDeferredAsyncVolumeLoadStarted();
    const_cast<VolumeRendererComponent*>(this)->ResolvePendingVolumeField();
    return m_volumeField.Get();
}

const Resources::ResourceHandle<Resources::VolumeField>& VolumeRendererComponent::GetVolumeFieldHandle() const {
    const_cast<VolumeRendererComponent*>(this)->EnsureDeferredAsyncVolumeLoadStarted();
    const_cast<VolumeRendererComponent*>(this)->ResolvePendingVolumeField();
    return m_volumeField;
}

void VolumeRendererComponent::SetVolumeFieldPath(const std::string& volumeFieldPath) {
    m_pendingVolumeLoad.reset();
    m_asyncVolumeLoadRequested = false;
    m_volumeFieldPath = volumeFieldPath;
    if (m_volumeFieldPath.empty()) {
        m_volumeField.Reset();
        m_volumeFieldRef.Reset();
        return;
    }

    m_volumeField = Resources::ResourceManager::Get().Load<Resources::VolumeField>(m_volumeFieldPath.c_str());
    if (!Resources::ResourceManager::Get().TryGetAssetRef(
            m_volumeFieldPath.c_str(),
            Resources::ResourceType::VolumeField,
            m_volumeFieldRef)) {
        m_volumeFieldRef.Reset();
    }
}

void VolumeRendererComponent::SetVolumeField(
    const Resources::ResourceHandle<Resources::VolumeField>& volumeField) {
    m_pendingVolumeLoad.reset();
    m_asyncVolumeLoadRequested = false;
    m_volumeField = volumeField;
    m_volumeFieldPath = VolumeFieldPathFromHandle(volumeField);
    if (m_volumeFieldPath.empty() ||
        !Resources::ResourceManager::Get().TryGetAssetRef(
            m_volumeFieldPath.c_str(),
            Resources::ResourceType::VolumeField,
            m_volumeFieldRef)) {
        m_volumeFieldRef.Reset();
    }
}

void VolumeRendererComponent::SetVolumeField(Resources::VolumeField* volumeField) {
    SetVolumeField(Resources::ResourceHandle<Resources::VolumeField>(volumeField));
}

void VolumeRendererComponent::ClearVolumeField() {
    m_pendingVolumeLoad.reset();
    m_asyncVolumeLoadRequested = false;
    m_volumeField.Reset();
    m_volumeFieldPath.clear();
    m_volumeFieldRef.Reset();
}

Resources::Material* VolumeRendererComponent::GetMaterial() const {
    const_cast<VolumeRendererComponent*>(this)->EnsureDeferredAsyncMaterialLoadStarted();
    const_cast<VolumeRendererComponent*>(this)->ResolvePendingMaterial();
    return m_material.Get();
}

const Resources::ResourceHandle<Resources::Material>& VolumeRendererComponent::GetMaterialHandle() const {
    const_cast<VolumeRendererComponent*>(this)->EnsureDeferredAsyncMaterialLoadStarted();
    const_cast<VolumeRendererComponent*>(this)->ResolvePendingMaterial();
    return m_material;
}

void VolumeRendererComponent::SetMaterialPath(const std::string& materialPath) {
    m_pendingMaterialLoad.reset();
    m_asyncMaterialLoadRequested = false;
    m_materialPath = materialPath;
    if (m_materialPath.empty()) {
        m_material.Reset();
        m_materialRef.Reset();
        return;
    }

    m_material = Resources::ResourceManager::Get().Load<Resources::Material>(m_materialPath.c_str());
    if (!Resources::ResourceManager::Get().TryGetAssetRef(
            m_materialPath.c_str(),
            Resources::ResourceType::Material,
            m_materialRef)) {
        m_materialRef.Reset();
    }
}

void VolumeRendererComponent::SetMaterial(
    const Resources::ResourceHandle<Resources::Material>& material) {
    m_pendingMaterialLoad.reset();
    m_asyncMaterialLoadRequested = false;
    m_material = material;
    m_materialPath = MaterialPathFromHandle(material);
    if (m_materialPath.empty() ||
        !Resources::ResourceManager::Get().TryGetAssetRef(
            m_materialPath.c_str(),
            Resources::ResourceType::Material,
            m_materialRef)) {
        m_materialRef.Reset();
    }
}

void VolumeRendererComponent::SetMaterial(Resources::Material* material) {
    SetMaterial(Resources::ResourceHandle<Resources::Material>(material));
}

void VolumeRendererComponent::ClearMaterial() {
    m_pendingMaterialLoad.reset();
    m_asyncMaterialLoadRequested = false;
    m_material.Reset();
    m_materialPath.clear();
    m_materialRef.Reset();
}

void VolumeRendererComponent::Serialize(std::ostream& os) const {
    Resources::AssetRef volumeFieldRef = m_volumeFieldRef;
    if (!volumeFieldRef.IsValid() &&
        !m_volumeFieldPath.empty() &&
        !HasVirtualPathScheme(m_volumeFieldPath) &&
        Resources::ResourceManager::Get().TryGetAssetRef(
            m_volumeFieldPath.c_str(),
            Resources::ResourceType::VolumeField,
            volumeFieldRef)) {
    }

    Resources::AssetRef materialRef = m_materialRef;
    if (!materialRef.IsValid() &&
        !m_materialPath.empty() &&
        !HasVirtualPathScheme(m_materialPath) &&
        Resources::ResourceManager::Get().TryGetAssetRef(
            m_materialPath.c_str(),
            Resources::ResourceType::Material,
            materialRef)) {
    }

    os << "volumeRef=" << EncodeAssetRef(volumeFieldRef) << ";";
    if (!volumeFieldRef.IsValid() && !m_volumeFieldPath.empty() && HasVirtualPathScheme(m_volumeFieldPath)) {
        os << "volumePath=" << m_volumeFieldPath << ";";
    }

    os << "materialRef=" << EncodeAssetRef(materialRef) << ";";
    if (!materialRef.IsValid() && !m_materialPath.empty() && HasVirtualPathScheme(m_materialPath)) {
        os << "materialPath=" << m_materialPath << ";";
    }

    os << "castShadows=" << (m_castShadows ? 1 : 0) << ";";
    os << "receiveShadows=" << (m_receiveShadows ? 1 : 0) << ";";
}

void VolumeRendererComponent::Deserialize(std::istream& is) {
    ClearVolumeField();
    ClearMaterial();
    m_castShadows = true;
    m_receiveShadows = true;

    std::string token;
    std::string pendingVolumePath;
    Resources::AssetRef pendingVolumeRef;
    std::string pendingMaterialPath;
    Resources::AssetRef pendingMaterialRef;
    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 == "volumePath") {
            pendingVolumePath = value;
        } else if (key == "volumeRef") {
            TryDecodeAssetRef(value, pendingVolumeRef);
        } else if (key == "materialPath") {
            pendingMaterialPath = value;
        } else if (key == "materialRef") {
            TryDecodeAssetRef(value, pendingMaterialRef);
        } else if (key == "castShadows") {
            m_castShadows = (std::stoi(value) != 0);
        } else if (key == "receiveShadows") {
            m_receiveShadows = (std::stoi(value) != 0);
        }
    }

    if (pendingVolumeRef.IsValid()) {
        bool restoredOrQueued = false;
        m_volumeFieldRef = pendingVolumeRef;
        if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
            Containers::String resolvedPath;
            if (Resources::ResourceManager::Get().TryResolveAssetPath(pendingVolumeRef, resolvedPath)) {
                m_volumeFieldPath = ToStdString(resolvedPath);
                restoredOrQueued = true;
            }
        }

        if (!restoredOrQueued) {
            m_volumeField = Resources::ResourceManager::Get().Load<Resources::VolumeField>(pendingVolumeRef);
            m_volumeFieldPath = m_volumeField.Get() != nullptr
                ? VolumeFieldPathFromHandle(m_volumeField)
                : pendingVolumePath;
        }
    } else if (!pendingVolumePath.empty() && HasVirtualPathScheme(pendingVolumePath)) {
        if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
            m_volumeFieldPath = pendingVolumePath;
        } else {
            SetVolumeFieldPath(pendingVolumePath);
        }
    }

    if (pendingMaterialRef.IsValid()) {
        bool restoredOrQueued = false;
        m_materialRef = pendingMaterialRef;
        if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
            Containers::String resolvedPath;
            if (Resources::ResourceManager::Get().TryResolveAssetPath(pendingMaterialRef, resolvedPath)) {
                m_materialPath = ToStdString(resolvedPath);
                restoredOrQueued = true;
            }
        }

        if (!restoredOrQueued) {
            m_material = Resources::ResourceManager::Get().Load<Resources::Material>(pendingMaterialRef);
            m_materialPath = m_material.Get() != nullptr
                ? MaterialPathFromHandle(m_material)
                : pendingMaterialPath;
        }
    } else if (!pendingMaterialPath.empty() && HasVirtualPathScheme(pendingMaterialPath)) {
        if (Resources::ResourceManager::Get().IsDeferredSceneLoadEnabled()) {
            m_materialPath = pendingMaterialPath;
        } else {
            SetMaterialPath(pendingMaterialPath);
        }
    }
}

void VolumeRendererComponent::BeginAsyncVolumeLoad(const std::string& volumeFieldPath) {
    if (volumeFieldPath.empty()) {
        m_pendingVolumeLoad.reset();
        m_asyncVolumeLoadRequested = false;
        m_volumeField.Reset();
        return;
    }

    m_asyncVolumeLoadRequested = true;
    m_volumeField.Reset();
    m_pendingVolumeLoad = std::make_shared<PendingVolumeLoadState>();
    m_pendingVolumeLoad->requestedAtMs = GetVolumeTraceSteadyMs();
    LogVolumeTraceFileSystem(
        "BeginAsyncVolumeLoad path=" + volumeFieldPath +
        " steady_ms=" + std::to_string(m_pendingVolumeLoad->requestedAtMs));
    std::weak_ptr<PendingVolumeLoadState> weakState = m_pendingVolumeLoad;
    Resources::ResourceManager::Get().LoadAsync(
        volumeFieldPath.c_str(),
        Resources::ResourceType::VolumeField,
        [weakState, volumeFieldPath](Resources::LoadResult result) {
            if (std::shared_ptr<PendingVolumeLoadState> state = weakState.lock()) {
                const uint64_t completedAtMs = GetVolumeTraceSteadyMs();
                const bool succeeded = static_cast<bool>(result) && result.resource != nullptr;
                size_t payloadBytes = 0u;
                if (succeeded) {
                    if (auto* volumeField = static_cast<Resources::VolumeField*>(result.resource)) {
                        payloadBytes = volumeField->GetPayloadSize();
                    }
                }
                LogVolumeTraceFileSystem(
                    "AsyncVolumeLoadCompleted path=" + volumeFieldPath +
                    " steady_ms=" + std::to_string(completedAtMs) +
                    " elapsed_ms=" + std::to_string(completedAtMs - state->requestedAtMs) +
                    " success=" + std::to_string(succeeded ? 1 : 0) +
                    " payload_bytes=" + std::to_string(payloadBytes));
                state->result = std::move(result);
                state->completed = true;
            }
        });
}

void VolumeRendererComponent::EnsureDeferredAsyncVolumeLoadStarted() {
    if (m_asyncVolumeLoadRequested || m_volumeField.Get() != nullptr || m_volumeFieldPath.empty()) {
        return;
    }

    BeginAsyncVolumeLoad(m_volumeFieldPath);
}

void VolumeRendererComponent::ResolvePendingVolumeField() {
    if (!m_pendingVolumeLoad || !m_pendingVolumeLoad->completed) {
        return;
    }

    std::shared_ptr<PendingVolumeLoadState> completedLoad = std::move(m_pendingVolumeLoad);
    m_pendingVolumeLoad.reset();

    if (!completedLoad->result || completedLoad->result.resource == nullptr) {
        return;
    }

    m_volumeField = Resources::ResourceHandle<Resources::VolumeField>(
        static_cast<Resources::VolumeField*>(completedLoad->result.resource));
    if (m_volumeField.Get() == nullptr) {
        return;
    }

    const uint64_t resolvedAtMs = GetVolumeTraceSteadyMs();
    LogVolumeTraceFileSystem(
        "ResolvePendingVolumeField path=" + VolumeFieldPathFromHandle(m_volumeField) +
        " steady_ms=" + std::to_string(resolvedAtMs) +
        " elapsed_ms=" + std::to_string(resolvedAtMs - completedLoad->requestedAtMs) +
        " payload_bytes=" + std::to_string(m_volumeField->GetPayloadSize()));

    m_volumeFieldPath = VolumeFieldPathFromHandle(m_volumeField);
    if (!Resources::ResourceManager::Get().TryGetAssetRef(
            m_volumeFieldPath.c_str(),
            Resources::ResourceType::VolumeField,
            m_volumeFieldRef)) {
        m_volumeFieldRef.Reset();
    }
}

void VolumeRendererComponent::BeginAsyncMaterialLoad(const std::string& materialPath) {
    if (materialPath.empty()) {
        m_pendingMaterialLoad.reset();
        m_asyncMaterialLoadRequested = false;
        m_material.Reset();
        return;
    }

    m_asyncMaterialLoadRequested = true;
    m_material.Reset();
    m_pendingMaterialLoad = std::make_shared<PendingMaterialLoadState>();
    std::weak_ptr<PendingMaterialLoadState> weakState = m_pendingMaterialLoad;
    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 VolumeRendererComponent::EnsureDeferredAsyncMaterialLoadStarted() {
    if (m_asyncMaterialLoadRequested || m_material.Get() != nullptr || m_materialPath.empty()) {
        return;
    }

    BeginAsyncMaterialLoad(m_materialPath);
}

void VolumeRendererComponent::ResolvePendingMaterial() {
    if (!m_pendingMaterialLoad || !m_pendingMaterialLoad->completed) {
        return;
    }

    std::shared_ptr<PendingMaterialLoadState> completedLoad = std::move(m_pendingMaterialLoad);
    m_pendingMaterialLoad.reset();

    if (!completedLoad->result || completedLoad->result.resource == nullptr) {
        return;
    }

    m_material = Resources::ResourceHandle<Resources::Material>(
        static_cast<Resources::Material*>(completedLoad->result.resource));
    if (m_material.Get() == nullptr) {
        return;
    }

    m_materialPath = MaterialPathFromHandle(m_material);
    if (!Resources::ResourceManager::Get().TryGetAssetRef(
            m_materialPath.c_str(),
            Resources::ResourceType::Material,
            m_materialRef)) {
        m_materialRef.Reset();
    }
}

} // namespace Components
} // namespace XCEngine