#pragma once

#include <limits>
#include <type_traits>

#include <cstdint>

#include "uart_config.hpp"
#include "uart_vcp.hpp"

namespace uart {

namespace detail {

    template<typename...>
    struct always_false : std::false_type {
    };
    template<typename... Ts>
    inline constexpr auto always_false_v = always_false<Ts...>::value;

    template<typename T, T Limit, size_t Base>
    static constexpr size_t cntDigits()
    {
        T num = Limit;
        size_t cnt = 0;

        do {
            num /= Base;
            ++cnt;
        } while(num > 0);

        return cnt;
    }

    template<typename T, size_t Base>
    static constexpr size_t maxNumDigits()
    {
        constexpr T MinVal = std::numeric_limits<T>::min();
        constexpr T MaxVal = std::numeric_limits<T>::max();

        constexpr T MinDigits = cntDigits<T, MinVal, Base>();
        constexpr T MaxDigits = cntDigits<T, MaxVal, Base>();

        return (MinDigits < MaxDigits) ? MaxDigits : MinDigits;
    }

} // namespace detail

template<class Driver>
class Uart {
  public:
    // Constructing a uart object does not initialize the driver to allow different specializations with the same
    // back-end to exists at the same time
    // Note that init must be called every time when switching specializations with the same back-end
    Uart() = default;

    // Moving and copying uart objects is not supported
    Uart(const Uart&) = delete;
    Uart(Uart&&) = delete;
    Uart& operator=(const Uart&) = delete;
    Uart& operator=(Uart&&) = delete;

    // Before using the uart init must be called
    static void init() { Driver::init(); }

    static void txByte(const uint8_t& byte) { Driver::txByte(byte); }

    static bool rxByte(uint8_t& byte) { return Driver::rxByte(byte); }

    static bool peek(uint8_t& byte) { return Driver::peek(byte); }

    static bool peek() { return Driver::peek(); }

    static void flushTx() { Driver::flushTx(); }

    static void txString(const char* str)
    {
        static_assert(Driver::DATA_BITS == DataBits::EIGHT, "Strings are only supported with 8 data bits");

        while(char ch = *str++)
            txByte(ch);
    }

    template<typename T, size_t Base = 10, size_t Padding = 0, char PadChar = '0', bool LowerCase = true>
    static void txNumber(const T& val)
    {
        static_assert(std::is_integral_v<T>, "Only supported on integral types");
        static_assert(Base >= 2, "Numbers with base less than 2 make no sense");
        static_assert(Base <= 16, "Numbers with base higher than 16 are not supported");
        static_assert(Padding <= detail::maxNumDigits<T, Base>(), "Cannot pad more than maximum length of number");

        constexpr char AlphaChar = (LowerCase) ? 'a' : 'A';
        constexpr size_t NumDigits = detail::maxNumDigits<T, Base>();

        T digits = val;

        if(digits < 0) {
            digits = -digits;
            txByte('-');
        }

        uint8_t buffer[NumDigits];
        uint8_t* bufEnd = buffer + NumDigits - 1;

        do {
            const uint8_t lastDigit = digits % Base;
            *bufEnd-- = (lastDigit < 10) ? ('0' + lastDigit) : (AlphaChar + lastDigit - 10);
            digits /= Base;
        } while(digits > 0);

        if(Padding > 0) {
            size_t strLen = buffer + NumDigits - (bufEnd + 1);

            if(Padding > strLen) {
                for(size_t i = Padding; i > strLen && bufEnd >= buffer; --i) {
                    *bufEnd-- = PadChar;
                }
            }
        }

        for(uint8_t* buf = bufEnd + 1; buf < buffer + NumDigits; ++buf) {
            txByte(*buf);
        }
    }

    //////////////////////////////////////////////////////////////////////////
    // Output stream overloads

    Uart& operator<<(const char* str)
    {
        txString(str);
        return *this;
    }

    Uart& operator<<(const char& val)
    {
        txByte(val);
        return *this;
    }

    Uart& operator<<(const signed char& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const unsigned char& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const short& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const unsigned short& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const int& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const unsigned int& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const long& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const unsigned long& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const long long& val)
    {
        txNumber(val);
        return *this;
    }

    Uart& operator<<(const unsigned long long& val)
    {
        txNumber(val);
        return *this;
    }

    template<typename... Ts>
    Uart& operator<<(float) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not supported by hardware");
    }

    template<typename... Ts>
    Uart& operator<<(double) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not supported by hardware");
    }

    template<typename... Ts>
    Uart& operator<<(long double) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not supported by hardware");
    }

    Uart& operator<<(const bool& val)
    {
        txString(val ? "true" : "false");
        return *this;
    }

    Uart& operator<<(const void* val)
    {
        txString("0x");
        txNumber<uint32_t, 16, 4, '0', false>(reinterpret_cast<uint32_t>(val));
        return *this;
    }

    //////////////////////////////////////////////////////////////////////////
    // Input stream overloads

    template<typename... Ts>
    Uart& operator>>(char&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(unsigned char&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(short&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(unsigned short&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(int&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(unsigned int&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(long&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(unsigned long&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(long long&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(unsigned long long&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(float&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not supported by hardware");
    }

    template<typename... Ts>
    Uart& operator>>(double&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not supported by hardware");
    }

    template<typename... Ts>
    Uart& operator>>(long double&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not supported by hardware");
    }

    template<typename... Ts>
    Uart& operator>>(bool&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }

    template<typename... Ts>
    Uart& operator>>(const void*&) const
    {
        static_assert(detail::always_false_v<Ts...>, "Not implemented");
    }
};

template<typename cfg = Config<>>
using Vcp = Uart<detail::VirtualComPort<cfg>>;

} // namespace uart