/*
see protocol.md for the protocol specification
*/

#ifndef __PROTOCOL_HPP
#define __PROTOCOL_HPP

#include <functional>
#include <limits>
#include <cmath>
//#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <cstring>
#include <fibre/cpp_utils.hpp>
#include <fibre/bufptr.hpp>
#include <fibre/simple_serdes.hpp>


typedef struct {
    uint16_t json_crc;
    uint16_t endpoint_id;
} endpoint_ref_t;


namespace fibre {
// These symbols are defined in the autogenerated endpoints.hpp
extern const unsigned char embedded_json[];
extern const size_t embedded_json_length;
extern const uint16_t json_crc_;
extern const uint32_t json_version_id_;
bool endpoint_handler(int idx, cbufptr_t* input_buffer, bufptr_t* output_buffer);
bool endpoint0_handler(cbufptr_t* input_buffer, bufptr_t* output_buffer);
bool is_endpoint_ref_valid(endpoint_ref_t endpoint_ref);
bool set_endpoint_from_float(endpoint_ref_t endpoint_ref, float value);
}



namespace fibre {
template<typename T, typename = void>
struct Codec {
    static std::optional<T> decode(cbufptr_t* buffer) { return std::nullopt; }
};

template<> struct Codec<bool> {
    static std::optional<bool> decode(cbufptr_t* buffer) { return (buffer->begin() == buffer->end()) ? std::nullopt : std::make_optional((bool)*(buffer->begin()++)); }
    static bool encode(bool value, bufptr_t* buffer) { return SimpleSerializer<uint8_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<int8_t> {
    static std::optional<int8_t> decode(cbufptr_t* buffer) { return SimpleSerializer<int8_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(int8_t value, bufptr_t* buffer) { return SimpleSerializer<int8_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<uint8_t> {
    static std::optional<uint8_t> decode(cbufptr_t* buffer) { return SimpleSerializer<uint8_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(uint8_t value, bufptr_t* buffer) { return SimpleSerializer<uint8_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<int16_t> {
    static std::optional<int16_t> decode(cbufptr_t* buffer) { return SimpleSerializer<int16_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(int16_t value, bufptr_t* buffer) { return SimpleSerializer<int16_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<uint16_t> {
    static std::optional<uint16_t> decode(cbufptr_t* buffer) { return SimpleSerializer<uint16_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(uint16_t value, bufptr_t* buffer) { return SimpleSerializer<uint16_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<int32_t> {
    static std::optional<int32_t> decode(cbufptr_t* buffer) { return SimpleSerializer<int32_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(int32_t value, bufptr_t* buffer) { return SimpleSerializer<int32_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<uint32_t> {
    static std::optional<uint32_t> decode(cbufptr_t* buffer) { return SimpleSerializer<uint32_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(uint32_t value, bufptr_t* buffer) { return SimpleSerializer<uint32_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<int64_t> {
    static std::optional<int64_t> decode(cbufptr_t* buffer) { return SimpleSerializer<int64_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(int64_t value, bufptr_t* buffer) { return SimpleSerializer<int64_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<uint64_t> {
    static std::optional<uint64_t> decode(cbufptr_t* buffer) { return SimpleSerializer<uint64_t, false>::read(&(buffer->begin()), buffer->end()); }
    static bool encode(uint64_t value, bufptr_t* buffer) { return SimpleSerializer<uint64_t, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<float> {
    static std::optional<float> decode(cbufptr_t* buffer) {
        std::optional<uint32_t> int_val = Codec<uint32_t>::decode(buffer);
        return int_val.has_value() ? std::optional<float>(*reinterpret_cast<float*>(&*int_val)) : std::nullopt;
    }
    static bool encode(float value, bufptr_t* buffer) {
        void* ptr = &value;
        return Codec<uint32_t>::encode(*reinterpret_cast<uint32_t*>(ptr), buffer);
    }
};
template<typename T>
struct Codec<T, std::enable_if_t<std::is_enum<T>::value>> {
    using int_type = std::underlying_type_t<T>;
    static std::optional<T> decode(cbufptr_t* buffer) {
        std::optional<int_type> int_val = SimpleSerializer<int_type, false>::read(&(buffer->begin()), buffer->end());
        return int_val.has_value() ? std::make_optional(static_cast<T>(*int_val)) : std::nullopt;
    }
    static bool encode(T value, bufptr_t* buffer) { return SimpleSerializer<int_type, false>::write(value, &(buffer->begin()), buffer->end()); }
};
template<> struct Codec<endpoint_ref_t> {
    static std::optional<endpoint_ref_t> decode(cbufptr_t* buffer) {
        std::optional<uint16_t> val0 = SimpleSerializer<uint16_t, false>::read(&(buffer->begin()), buffer->end());
        std::optional<uint16_t> val1 = SimpleSerializer<uint16_t, false>::read(&(buffer->begin()), buffer->end());
        return (val0.has_value() && val1.has_value()) ? std::make_optional(endpoint_ref_t{*val1, *val0}) : std::nullopt;
    }
    static bool encode(endpoint_ref_t value, bufptr_t* buffer) {
        return SimpleSerializer<uint16_t, false>::write(value.endpoint_id, &(buffer->begin()), buffer->end())
            && SimpleSerializer<uint16_t, false>::write(value.json_crc, &(buffer->begin()), buffer->end());
    }
};
}


/* ToString / FromString functions -------------------------------------------*/
/*
* These functions are currently not used by Fibre and only here to
* support the ODrive ASCII protocol.
* TODO: find a general way for client code to augment endpoints with custom
* functions
*/

template<typename T>
struct format_traits_t;

// template<> struct format_traits_t<float> { using type = void;
//     static constexpr const char * fmt = "%f";
//     static constexpr const char * fmtp = "%f";
// };
template<> struct format_traits_t<long long> { using type = void;
    static constexpr const char * fmt = "%lld";
    static constexpr const char * fmtp = "%lld";
    using scn_type = long long;
};
template<> struct format_traits_t<unsigned long long> { using type = void;
    static constexpr const char * fmt = "%llu";
    static constexpr const char * fmtp = "%llu";
    using scn_type = unsigned long long;
};
template<> struct format_traits_t<long> { using type = void;
    static constexpr const char * fmt = "%ld";
    static constexpr const char * fmtp = "%ld";
    using scn_type = long;
};
template<> struct format_traits_t<unsigned long> { using type = void;
    static constexpr const char * fmt = "%lu";
    static constexpr const char * fmtp = "%lu";
    using scn_type = unsigned long;
};
template<> struct format_traits_t<int> { using type = void;
    static constexpr const char * fmt = "%d";
    static constexpr const char * fmtp = "%d";
    using scn_type = int;
};
template<> struct format_traits_t<unsigned int> { using type = void;
    static constexpr const char * fmt = "%u";
    static constexpr const char * fmtp = "%u";
    using scn_type = unsigned int;
};
template<> struct format_traits_t<short> { using type = void;
    static constexpr const char * fmt = "%d";
    static constexpr const char * fmtp = "%d";
    using scn_type = int;
};
template<> struct format_traits_t<unsigned short> { using type = void;
    static constexpr const char * fmt = "%u";
    static constexpr const char * fmtp = "%u";
    using scn_type = unsigned int;
};
template<> struct format_traits_t<char> { using type = void;
    static constexpr const char * fmt = "%d";
    static constexpr const char * fmtp = "%d";
    using scn_type = int;
};
template<> struct format_traits_t<unsigned char> { using type = void;
    static constexpr const char * fmt = "%u";
    static constexpr const char * fmtp = "%u";
    using scn_type = unsigned int;
};

template<typename T, typename = typename format_traits_t<T>::type>
static bool to_string(const T& value, char * buffer, size_t length, int) {
    snprintf(buffer, length, format_traits_t<T>::fmtp, value);
    return true;
}
// Special case for float because printf promotes float to double, and we get warnings
template<typename T = float>
static bool to_string(const float& value, char * buffer, size_t length, int) {
    snprintf(buffer, length, "%f", (double)value);
    return true;
}
template<typename T = bool>
static bool to_string(const bool& value, char * buffer, size_t length, int) {
    buffer[0] = value ? '1' : '0';
    buffer[1] = 0;
    return true;
}
template<typename T>
static bool to_string(const T& value, char * buffer, size_t length, ...) {
    return false;
}

template<typename T, typename = typename format_traits_t<T>::type>
static bool from_string(const char * buffer, size_t length, T* property, int) {
    // sscanf doesn't work well with integers that are smaller than int, so we
    // first scan into an appropriate int type and then convert it.
    // (e.g. %hhu has been observed to not work on some compilers)
    typename format_traits_t<T>::scn_type val;
    if (sscanf(buffer, format_traits_t<T>::fmt, &val) == 1) {
        *property = (T)val;
        return true;
    } else {
        return false;
    }
}
// Special case for float because printf promotes float to double, and we get warnings
template<typename T = float>
static bool from_string(const char * buffer, size_t length, float* property, int) {
    return sscanf(buffer, "%f", property) == 1;
}
template<typename T = bool>
static bool from_string(const char * buffer, size_t length, bool* property, int) {
    int val;
    if (sscanf(buffer, "%d", &val) != 1)
        return false;
    *property = val;
    return true;
}
template<typename T>
static bool from_string(const char * buffer, size_t length, T* property, ...) {
    return false;
}


//template<typename T, typename = typename std>
//bool set_from_float_ex(float value, T* property) {
//    return false;
//}

namespace conversion {
//template<typename T>
template<typename T>
bool set_from_float_ex(float value, float* property, int) {
    return *property = value, true;
}
template<typename T>
bool set_from_float_ex(float value, bool* property, int) {
    return *property = (value >= 0.0f), true;
}
template<typename T, typename = std::enable_if_t<std::is_integral<T>::value && !std::is_const<T>::value>>
bool set_from_float_ex(float value, T* property, int) {
    return *property = static_cast<T>(std::round(value)), true;
}
template<typename T>
bool set_from_float_ex(float value, T* property, ...) {
    return false;
}
template<typename T>
bool set_from_float(float value, T* property) {
    return set_from_float_ex<T>(value, property, 0);
}
}


template<typename T>
struct Property {
    Property(void* ctx, T(*getter)(void*), void(*setter)(void*, T))
        : ctx_(ctx), getter_(getter), setter_(setter) {}
    Property(T* ctx)
        : ctx_(ctx), getter_([](void* ctx){ return *(T*)ctx; }), setter_([](void* ctx, T val){ *(T*)ctx = val; }) {}
    Property& operator*() { return *this; }
    Property* operator->() { return this; }

    T read() const {
        return (*getter_)(ctx_);
    }

    T exchange(std::optional<T> value) const {
        T old_value = (*getter_)(ctx_);
        if (value.has_value()) {
            (*setter_)(ctx_, *value);
        }
        return old_value;
    }
    
    void* ctx_;
    T(*getter_)(void*);
    void(*setter_)(void*, T);
};

template<typename T>
struct Property<const T> {
    Property(void* ctx, T(*getter)(void*))
        : ctx_(ctx), getter_(getter) {}
    Property(const T* ctx)
        : ctx_(const_cast<T*>(ctx)), getter_([](void* ctx){ return *(const T*)ctx; }) {}
    Property& operator*() { return *this; }
    Property* operator->() { return this; }

    T read() const {
        return (*getter_)(ctx_);
    }

    void* ctx_;
    T(*getter_)(void*);
};


#endif