#pragma once

#include <string>
#include <vector>
#include <cstdint>


namespace DB
{

/// Data types for representing elementary values from a database in RAM.

struct Null {};

using UInt8 = uint8_t;
using UInt16 = uint16_t;
using UInt32 = uint32_t;
using UInt64 = uint64_t;

using Int8 = int8_t;
using Int16 = int16_t;
using Int32 = int32_t;
using Int64 = int64_t;

using Float32 = float;
using Float64 = double;

using String = std::string;


/** Note that for types not used in DB, IsNumber is false.
  */
template <typename T> constexpr bool IsNumber = false;

template <> constexpr bool IsNumber<UInt8> = true;
template <> constexpr bool IsNumber<UInt16> = true;
template <> constexpr bool IsNumber<UInt32> = true;
template <> constexpr bool IsNumber<UInt64> = true;
template <> constexpr bool IsNumber<Int8> = true;
template <> constexpr bool IsNumber<Int16> = true;
template <> constexpr bool IsNumber<Int32> = true;
template <> constexpr bool IsNumber<Int64> = true;
template <> constexpr bool IsNumber<Float32> = true;
template <> constexpr bool IsNumber<Float64> = true;

template <typename T> struct TypeName;

template <> struct TypeName<UInt8>   { static const char * get() { return "UInt8";   } };
template <> struct TypeName<UInt16>  { static const char * get() { return "UInt16";  } };
template <> struct TypeName<UInt32>  { static const char * get() { return "UInt32";  } };
template <> struct TypeName<UInt64>  { static const char * get() { return "UInt64";  } };
template <> struct TypeName<Int8>    { static const char * get() { return "Int8";    } };
template <> struct TypeName<Int16>   { static const char * get() { return "Int16";   } };
template <> struct TypeName<Int32>   { static const char * get() { return "Int32";   } };
template <> struct TypeName<Int64>   { static const char * get() { return "Int64";   } };
template <> struct TypeName<Float32> { static const char * get() { return "Float32"; } };
template <> struct TypeName<Float64> { static const char * get() { return "Float64"; } };
template <> struct TypeName<String>  { static const char * get() { return "String";  } };

template <typename T> struct TypeNumber;

/// 0 reserved for types without number
template <> struct TypeNumber<UInt8>    { static constexpr const size_t value = 1;  };
template <> struct TypeNumber<UInt16>   { static constexpr const size_t value = 2;  };
template <> struct TypeNumber<UInt32>   { static constexpr const size_t value = 3;  };
template <> struct TypeNumber<UInt64>   { static constexpr const size_t value = 4;  };
/// 5 reserved for TypeNumber<UInt128>
template <> struct TypeNumber<Float32>  { static constexpr const size_t value = 7;  };
template <> struct TypeNumber<Float64>  { static constexpr const size_t value = 8;  };
template <> struct TypeNumber<Int8>     { static constexpr const size_t value = 9;  };
template <> struct TypeNumber<Int16>    { static constexpr const size_t value = 10; };
template <> struct TypeNumber<Int32>    { static constexpr const size_t value = 11; };
template <> struct TypeNumber<Int64>    { static constexpr const size_t value = 12; };
/// 13 reserved for TypeNumber<Int128>

/// Not a data type in database, defined just for convenience.
using Strings = std::vector<String>;

}

#if 1 /// __int128
namespace DB
{

using Int128 = __int128;
template <> constexpr bool IsNumber<Int128> = true;
template <> struct TypeName<Int128>  { static const char * get() { return "Int128";  } };
template <> struct TypeNumber<Int128>   { static constexpr const size_t value = 13; };

}

namespace std
{

template <> struct is_signed<__int128>
{
    static constexpr bool value = true;
};

template <> struct is_unsigned<__int128>
{
    static constexpr bool value = false;
};

template <> struct is_integral<__int128>
{
    static constexpr bool value = true;
};

template <> struct is_arithmetic<__int128>
{
    static constexpr bool value = true;
};

}
#endif


namespace DB
{
    /// Own FieldType for Decimal
    template <typename T>
    class Dec
    {
    public:
        using NativeType = T;

        Dec() = default;
        Dec(Dec<T> &&) = default;
        Dec(const Dec<T> &) = default;

        Dec(const T & value_)
        :   value(value_)
        {}

        template <typename U>
        Dec(const Dec<U> & x)
        :   value(x)
        {}

        constexpr Dec<T> & operator = (Dec<T> &&) = default;
        constexpr Dec<T> & operator = (const Dec<T> &) = default;

        operator T () const { return value; }

        const Dec<T> & operator += (const T & x) { value += x; return *this; }
        const Dec<T> & operator -= (const T & x) { value -= x; return *this; }
        const Dec<T> & operator *= (const T & x) { value *= x; return *this; }
        const Dec<T> & operator /= (const T & x) { value /= x; return *this; }
        const Dec<T> & operator %= (const T & x) { value %= x; return *this; }

    private:
        T value;
    };

    using Dec32 = Dec<Int32>;
    using Dec64 = Dec<Int64>;
    using Dec128 = Dec<Int128>;

    template <> struct TypeName<Dec32>   { static const char * get() { return "Dec32";   } };
    template <> struct TypeName<Dec64>   { static const char * get() { return "Dec64";   } };
    template <> struct TypeName<Dec128>  { static const char * get() { return "Dec128";  } };

    template <> struct TypeNumber<Dec32>    { static constexpr const size_t value = 16; };
    template <> struct TypeNumber<Dec64>    { static constexpr const size_t value = 17; };
    template <> struct TypeNumber<Dec128>   { static constexpr const size_t value = 18; };
}