#include <Functions/FunctionFactory.h>
#include <Functions/FunctionUnaryArithmetic.h>
#include <DataTypes/NumberTraits.h>


namespace DB
{
template <typename A>
struct SignImpl
{
    using ResultType = Int8;
    static const constexpr bool allow_fixed_string = false;
    static const constexpr bool allow_string_integer = false;

    static inline NO_SANITIZE_UNDEFINED ResultType apply(A a)
    {
        if constexpr (is_decimal<A> || std::is_floating_point_v<A>)
            return a < A(0) ? -1 : a == A(0) ? 0 : 1;
        else if constexpr (is_signed_v<A>)
            return a < 0 ? -1 : a == 0 ? 0 : 1;
        else if constexpr (is_unsigned_v<A>)
            return a == 0 ? 0 : 1;
    }

#if USE_EMBEDDED_COMPILER
    static constexpr bool compilable = false;
#endif
};

struct NameSign
{
    static constexpr auto name = "sign";
};
using FunctionSign = FunctionUnaryArithmetic<SignImpl, NameSign, false>;

template <>
struct FunctionUnaryArithmeticMonotonicity<NameSign>
{
    static bool has() { return true; }
    static IFunction::Monotonicity get(const Field &, const Field &)
    {
        return { .is_monotonic = true };
    }
};

void registerFunctionSign(FunctionFactory & factory)
{
    factory.registerFunction<FunctionSign>(FunctionFactory::CaseInsensitive);
}

}