ADCLIB/include/adclib/adclib_device.h

#pragma once

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

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


#include <snipplib/concepts/snplib_traits.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 "ADCLIB-DEVICE-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 "invalid command ID";
            case AdcDeviceErrorCode::ERROR_NO_ATTR_ID:
                return "invalid 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;
    }
};

inline std::error_code make_error_code(AdcDeviceErrorCode ec)
{
    return std::error_code(static_cast<int>(ec), AdcDeviceErrorCategory::get());
}


template <typename T>
concept adclib_command_exec_t = snplib::snplib_callable_c<T> && (snplib::snplib_func_traits_t<T>::arity == 0) &&
                                std::same_as<adc_error_t, typename snplib::snplib_func_traits_t<T>::ret_t>;

template <typename T>
concept adclib_attr_getter_c = std::same_as<T, std::nullptr_t> || requires(T t) {
    { t() } -> adc_result_c;
};

template <typename T>
concept adclib_attr_setter_c =
    std::same_as<T, std::nullptr_t> || (snplib::snplib_callable_c<T> && (snplib::snplib_func_traits_t<T>::arity >= 1) &&
                                        std::same_as<adc_error_t, typename snplib::snplib_func_traits_t<T>::ret_t>);


// deduce value type from getter and setter
template <adclib_attr_getter_c GT, adclib_attr_setter_c ST>
using snplib_attr_value_deduced_t =
    std::conditional_t<std::is_null_pointer_v<GT>,
                       std::conditional_t<std::is_null_pointer_v<ST>, void, snplib::snplib_func_arg1_t<ST>>,
                       typename std::invoke_result_t<GT>::value_type>;


template <std::formattable<char> DEV_ID_T = std::string,
          std::formattable<char> ATTR_ID_T = std::string,
          std::formattable<char> CMD_ID_T = std::string>
class AdcGenericDevice
{
protected:
    template <typename VT>
    struct attr_t {
        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>() const
        {
            auto attr = _dev._attrs.template get<attr_t<VT>>(_id);
            if (attr) {
                if (attr.value().getter) {
                    return attr.value().getter();
                }

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

            // error
            if (attr.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 attr = _dev._attrs.template get<attr_t<std::decay_t<VT>>>(_id);
            if (attr) {
                if (attr.value().setter) {
                    return attr.value().setter(std::forward<VT>(val));
                }

                return AdcDeviceErrorCode::ERROR_RO_ATTR;
            }

            if (attr.error() == 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;
    };

    DEV_ID_T _devId;

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

public:
    typedef DEV_ID_T device_id_t;
    typedef ATTR_ID_T attr_id_t;
    typedef CMD_ID_T cmd_id_t;

    enum AttrAccessType { ATTR_ACCESS_RW, ATTR_ACCESS_RO, ATTR_ACCESS_WO };

    AdcGenericDevice(device_id_t id) : _devId(id) {}

    virtual ~AdcGenericDevice() = default;

    device_id_t id() const
    {
        return _devId;
    }

    // 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 <adclib_command_exec_t 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, typename... VTs>
    template <adclib_attr_getter_c GT, adclib_attr_setter_c ST>
    void addAttr(ATTR_ID_T id, GT&& getter, ST&& setter)
    {
        using v_t = snplib_attr_value_deduced_t<GT, ST>;
        static_assert(!std::is_void_v<v_t>, "Getter and setter cannot be nullptr_t at the same time!");

        if constexpr (!std::is_null_pointer_v<GT> && !std::is_null_pointer_v<ST>) {
            static_assert(std::invocable<ST, v_t const&>, "Invalid setter argument type!");
        }

        _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 it->second();
        }

        return AdcDeviceErrorCode::ERROR_NO_CMD_ID;
    }

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


    // function-like access to attributes
    template <typename VT>
    adc_result_t<VT> attr(ATTR_ID_T id)
    {
        return attr_proxy_t{*this, std::move(id)};
    }

    template <typename VT>
    adc_error_t attr(ATTR_ID_T id, VT const& v)
    {
        return attr_proxy_t{*this, std::move(id)} = v;
    }
};

}  // namespace adc