#include "iwa/serialization.hpp"

namespace iwa
{
namespace
{
void propertyToYAML(const void* data, const iwa::Type& type, YAML::Emitter& emitter);
void propertyFromYAML(void* data, const iwa::Type& type, const YAML::Node& node);

struct PropertyEmitVisitor
{
    const void* data;
    YAML::Emitter& emitter;

    void operator()(const VoidType&)
    {
        emitter << YAML::Null;
    }

    void operator()(const BoolType&)
    {
        emitter << *static_cast<const bool*>(data);
    }

    void operator()(const IntType& type)
    {
        visitIntValue([&](auto&& value)
        {
            emitter << value;
        }, data, type);
    }

    void operator()(const FloatType& type)
    {
        visitFloatValue([&](auto&& value)
        {
            emitter << value;
        }, data, type);
    }

    void operator()(const CharType& type)
    {
        visitCharValue([&](auto&& value)
        {
            emitter << value;
        }, data, type);
    }

    void operator()(const ArrayType& type)
    {
        emitter << YAML::BeginSeq;
        for (std::size_t idx = 0; idx < type.arraySize; ++idx)
        {
            const std::byte* ele = static_cast<const std::byte*>(data) + (idx * type.arrayStride);
            propertyToYAML(ele, *type.baseType, emitter);
        }
        emitter << YAML::EndSeq;
    }

    void operator()(const ClassType&)
    {
        MIJIN_ERROR("Not implemented.");
        emitter << YAML::Null;
    }

    void operator()(const StructType& type)
    {
        structToYAML(data, *type.struct_, emitter);
    }

    void operator()(const PointerType&)
    {
        MIJIN_ERROR("Not implemented.");
        emitter << YAML::Null;
    }

    void operator()(const ReferenceType&)
    {
        MIJIN_ERROR("Not implemented.");
        emitter << YAML::Null;
    }

    void operator()(const ConstType& type)
    {
        propertyToYAML(data, *type.baseType, emitter);
    }

    void operator()(const VolatileType& type)
    {
        propertyToYAML(data, *type.baseType, emitter);
    }

    void operator()(const STDType& type)
    {
        switch (type)
        {
            case STDType::STRING:
                emitter << *static_cast<const std::string*>(data);
                break;
        }
    }

    void operator()(const BitFlagsType&)
    {
        MIJIN_ERROR("Not implemented.");
        emitter << YAML::Null;
    }
};

struct PropertyParseVisitor
{
    void* data;
    const YAML::Node& node;

    void operator()(const VoidType&) { /* ??? */ }

    void operator()(const BoolType&)
    {
        *static_cast<bool*>(data) = node.as<bool>();
    }

    void operator()(const IntType& type)
    {
        visitIntValue([&](auto& value)
        {
            using type_t = std::decay_t<decltype(value)>;
            value = node.as<type_t>();
        }, data, type);
    }

    void operator()(const FloatType& type)
    {
        visitFloatValue([&](auto& value)
        {
            using type_t = std::decay_t<decltype(value)>;
            value = node.as<type_t>();
        }, data, type);
    }

    void operator()(const CharType& type)
    {
        MIJIN_ERROR("Not implemented.");
        (void) type;
        // visitCharValue([&](auto& value)
        // {
        //     using type_t = std::decay_t<decltype(value)>;
        //     value = node.as<type_t>();
        // }, data, type);
    }

    void operator()(const ArrayType& type)
    {
        if (!node.IsSequence() || node.size() != type.arraySize)
        {
            throw std::runtime_error("Node not an array or size doesn't fit.");
        }
        for (std::size_t idx = 0; idx < type.arraySize; ++idx)
        {
            std::byte* ele = static_cast<std::byte*>(data) + (idx * type.arrayStride);
            propertyFromYAML(ele, *type.baseType, node[idx]);
        }
    }

    void operator()(const ClassType&)
    {
        MIJIN_ERROR("Not implemented.");
    }

    void operator()(const StructType& type)
    {
        structFromYAML(data, *type.struct_, node);
    }

    void operator()(const PointerType&)
    {
        MIJIN_ERROR("Not implemented.");
    }

    void operator()(const ReferenceType&)
    {
        MIJIN_ERROR("Not implemented.");
    }

    void operator()(const ConstType&)
    {
        MIJIN_ERROR("Can't read const values.");
    }

    void operator()(const VolatileType& type)
    {
        propertyFromYAML(data, *type.baseType, node);
    }

    void operator()(const STDType& type)
    {
        switch (type)
        {
            case STDType::STRING:
                *static_cast<std::string*>(data) = node.as<std::string>();
                break;
        }
    }

    void operator()(const BitFlagsType&)
    {
        MIJIN_ERROR("Not implemented.");
    }
};

void propertyToYAML(const void* data, const iwa::Type& type, YAML::Emitter& emitter)
{
    std::visit(PropertyEmitVisitor{data, emitter}, type);
}

void propertyFromYAML(void* data, const iwa::Type& type, const YAML::Node& node)
{
    std::visit(PropertyParseVisitor{data, node}, type);
}
}

void structToYAML(const void* data, const Struct& type, YAML::Emitter& emitter)
{
    emitter << YAML::BeginMap;
    for (const Property& property : type.getProperties())
    {
        emitter << YAML::Key << property.name;
        propertyToYAML(static_cast<const std::byte*>(data) + property.offset, property.type, emitter);
    }
    emitter << YAML::EndMap;
}

void structFromYAML(void* data, const Struct& type, const YAML::Node& node)
{
    if (!node.IsMap())
    {
        throw std::runtime_error("Expected map.");
    }
    for (const Property& property : type.getProperties())
    {
        const YAML::Node& propNode = node[property.name];
        if (propNode.IsNull()) {
            continue;
        }
        propertyFromYAML(static_cast<std::byte*>(data) + property.offset, property.type, propNode);
    }
}
}