ADCLIB/include/adclib/adclib_device.h

#pragma once

/****************************************************************************************
 *                          ABSTRACT DEVICE COMPONENTS LIBRARY                           *
 ****************************************************************************************/

#include <concepts>
#include <string>
#include <system_error>
#include <type_traits>
#include <utility>


// #include <snipplib/concepts/snplib_concepts.h>
#include <snipplib/containers/snplib_hmap.h>
#include <snipplib/serialization/snplib_serialization.h>



#include "adclib_common.h"


namespace adc
{


enum class AdcDeviceErrorCode : int {
    ERROR_OK,
    ERROR_NO_CMD_ID,
    ERROR_NO_ATTR_ID,
    ERROR_RO_ATTR,
    ERROR_WO_ATTR,
    ERROR_ATTR_RANGE,
    ERROR_SERIALIZATION,
    ERROR_DESERIALIZATION,
    ERROR_UNKNOWN
};

}  // namespace adc

namespace std
{

template <>
class is_error_code_enum<adc::AdcDeviceErrorCode> : public true_type
{
};

}  // namespace std



namespace adc
{

// error category

struct AdcDeviceErrorCategory : std::error_category {
    const char* name() const noexcept
    {
        return "MCC-DESERIALIZER-ERR-CATEGORY";
    }

    std::string message(int ec) const
    {
        AdcDeviceErrorCode err = static_cast<AdcDeviceErrorCode>(ec);

        switch (err) {
            case AdcDeviceErrorCode::ERROR_OK:
                return "OK";
            case AdcDeviceErrorCode::ERROR_NO_CMD_ID:
                return "invalud command ID";
            case AdcDeviceErrorCode::ERROR_NO_ATTR_ID:
                return "invalud attribute ID";
            case AdcDeviceErrorCode::ERROR_RO_ATTR:
                return "read-only attribute";
            case AdcDeviceErrorCode::ERROR_WO_ATTR:
                return "write-only attribute";
            case AdcDeviceErrorCode::ERROR_ATTR_RANGE:
                return "value is out of attribute range ";
            case AdcDeviceErrorCode::ERROR_SERIALIZATION:
                return "serialization error";
            case AdcDeviceErrorCode::ERROR_DESERIALIZATION:
                return "deserialization error";
            default:
                return "UNKNOWN";
        }
    }

    static const AdcDeviceErrorCategory& get()
    {
        static const AdcDeviceErrorCategory constInst;
        return constInst;
    }
};


template <std::formattable<char> ATTR_ID_T = std::string_view, std::formattable<char> CMD_ID_T = std::string_view>
class AdcGenericDevice
{
protected:
    template <typename VT>
    struct attr_t {
        ATTR_ID_T id;

        std::function<adc_result_t<VT>()> getter;
        std::function<adc_error_t(VT const&)> setter;

        adc_error_t serialize(snplib::snplib_output_char_range_c auto& output,
                              snplib::snplib_serialization_params_c auto const& params)
        {
            if (!getter) {
                return AdcDeviceErrorCode::ERROR_WO_ATTR;
            }

            auto val = getter();
            if (val) {
                auto ret = snplib::snplib_serializer_t<VT>{}(output, val.value(), params);
                if (ret) {
                    return snplib::snplib_deduced_error(ret, AdcDeviceErrorCode::ERROR_SERIALIZATION);
                }

                return AdcDeviceErrorCode::ERROR_OK;
            }

            return val.error();
        }

        adc_error_t deserialize(snplib::snplib_input_char_range_c auto const& input,
                                snplib::snplib_serialization_params_c auto const& params)
        {
            if (!setter) {
                return AdcDeviceErrorCode::ERROR_RO_ATTR;
            }

            VT value;  // WARNING: must be default-constructible!!!
            auto ret = snplib::snplib_deserializer_t<VT>{}(input, value, params);
            if (ret) {
                return snplib::snplib_deduced_error(ret, AdcDeviceErrorCode::ERROR_DESERIALIZATION);
            }

            return setter(value);
        }
    };


    struct attr_proxy_t {
        attr_proxy_t(AdcGenericDevice& dev, ATTR_ID_T id) : _dev(dev), _id(std::move(id)) {}

        template <typename VT>
        operator adc_result_t<VT>()
        {
            auto v = _dev._attrs.template get<VT>(_id);
            if (v) {
                return v.value();
            }

            // error
            if (v.error() == snplib::HeterogenMap<ATTR_ID_T>::ERROR_NO_ELEM) {
                return std::unexpected(AdcDeviceErrorCode::ERROR_NO_ATTR_ID);
            }

            return std::unexpected(AdcDeviceErrorCode::ERROR_UNKNOWN);
        }

        template <typename VT>
        adc_error_t operator=(VT&& val)
        {
            auto err = _dev._attrs.set(_id, std::forward<VT>(val));
            if (err == snplib::HeterogenMap<ATTR_ID_T>::ERROR_OK) {
                return AdcDeviceErrorCode::ERROR_OK;
            } else if (err == snplib::HeterogenMap<ATTR_ID_T>::ERROR_NO_ELEM) {
                return AdcDeviceErrorCode::ERROR_NO_ATTR_ID;
            } else {
                return AdcDeviceErrorCode::ERROR_UNKNOWN;
            }
        }

    protected:
        AdcGenericDevice& _dev;
        ATTR_ID_T _id;
    };

    std::unordered_map<CMD_ID_T, std::function<void()>> _commands{};
    snplib::HeterogenMap<ATTR_ID_T> _attrs{};

public:
    typedef ATTR_ID_T attr_id_t;
    typedef CMD_ID_T cmd_id_t;

    AdcGenericDevice() {}

    template <snplib::snplib_callable_c ET>
    void addCommand(CMD_ID_T id, ET&& exec_func)
    {
        _commands.emplace(std::move(id), std::forward<ET>(exec_func));
    }

    template <typename GT, typename ST>
    void addAttr(ATTR_ID_T id, GT&& getter, ST&& setter)
    {
        // deduce attribute value type
        using ret_t = std::invoke_result_t<GT>;
        using v_t = typename ret_t::value_type;

        static_assert(adc_result_c<ret_t>, "Invalid return type of the getter!");

        static_assert(std::invocable<ST, v_t const&>, "Invalid setter type!");
        static_assert(std::convertible_to<std::invoke_result_t<ST, v_t const&>, adc_error_t>,
                      "Invalid return type of the setter!");

        _attrs.push(std::move(id), attr_t<v_t>{.getter = std::forward<GT>(getter), .setter = std::forward<ST>(setter)});
    }

    adc_error_t operator()(CMD_ID_T id)
    {
        if (auto it = _commands.find(id); it != _commands.end()) {
            return (*it)();
        }

        return AdcDeviceErrorCode::ERROR_NO_CMD_ID;
    }


    template <typename VT>
    adc_result_t<VT> attr(ATTR_ID_T id)
    {
    }

    template <typename VT>
    adc_error_t attr(ATTR_ID_T id, VT const& v)
    {
    }

    auto operator[](ATTR_ID_T id)
    {
        return attr_proxy_t{*this, std::move(id)};
    }
};

}  // namespace adc