#!/usr/bin/env python
# coding: utf-8

# Copyright (c) 2002-2020 "Neo4j,"
# Neo4j Sweden AB [http://neo4j.com]
#
# This file is part of Neo4j.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


from math import isnan


def nano_add(x, y):
    """

        >>> 0.7 + 0.2
        0.8999999999999999
        >>> -0.7 + 0.2
        -0.49999999999999994
        >>> nano_add(0.7, 0.2)
        0.9
        >>> nano_add(-0.7, 0.2)
        -0.5

    :param x:
    :param y:
    :return:
    """
    return (int(1000000000 * x) + int(1000000000 * y)) / 1000000000


def nano_sub(x, y):
    """

        >>> 0.7 - 0.2
        0.49999999999999994
        >>> -0.7 - 0.2
        -0.8999999999999999
        >>> nano_sub(0.7, 0.2)
        0.5
        >>> nano_sub(-0.7, 0.2)
        -0.9

    :param x:
    :param y:
    :return:
    """
    return (int(1000000000 * x) - int(1000000000 * y)) / 1000000000


def nano_mul(x, y):
    """

        >>> 0.7 * 0.2
        0.13999999999999999
        >>> -0.7 * 0.2
        -0.13999999999999999
        >>> nano_mul(0.7, 0.2)
        0.14
        >>> nano_mul(-0.7, 0.2)
        -0.14

    :param x:
    :param y:
    :return:
    """
    return int(1000000000 * x) * int(1000000000 * y) / 1000000000000000000


def nano_div(x, y):
    """

        >>> 0.7 / 0.2
        3.4999999999999996
        >>> -0.7 / 0.2
        -3.4999999999999996
        >>> nano_div(0.7, 0.2)
        3.5
        >>> nano_div(-0.7, 0.2)
        -3.5

    :param x:
    :param y:
    :return:
    """
    return float(1000000000 * x) / int(1000000000 * y)


def nano_mod(x, y):
    """

        >>> 0.7 % 0.2
        0.09999999999999992
        >>> -0.7 % 0.2
        0.10000000000000009
        >>> nano_mod(0.7, 0.2)
        0.1
        >>> nano_mod(-0.7, 0.2)
        0.1

    :param x:
    :param y:
    :return:
    """
    number = type(x)
    nx = int(1000000000 * x)
    ny = int(1000000000 * y)
    q, r = divmod(nx, ny)
    return number(r / 1000000000)


def nano_divmod(x, y):
    """

        >>> divmod(0.7, 0.2)
        (3.0, 0.09999999999999992)
        >>> nano_divmod(0.7, 0.2)
        (3, 0.1)

    :param x:
    :param y:
    :return:
    """
    number = type(x)
    nx = int(1000000000 * x)
    ny = int(1000000000 * y)
    q, r = divmod(nx, ny)
    return int(q), number(r / 1000000000)


def signum(n):
    try:
        if isnan(n):
            return float("nan")
        if n > 0 or n == float("inf"):
            return 1
        if n < 0 or n == float("-inf"):
            return -1
        return 0
    except TypeError:
        raise TypeError(n)


def symmetric_divmod(dividend, divisor):
    number = type(dividend)
    if dividend >= 0:
        quotient, remainder = divmod(dividend, divisor)
        return int(quotient), number(remainder)
    else:
        quotient, remainder = divmod(-dividend, divisor)
        return -int(quotient), -number(remainder)


def round_half_to_even(n):
    """

        >>> round_half_to_even(3)
        3
        >>> round_half_to_even(3.2)
        3
        >>> round_half_to_even(3.5)
        4
        >>> round_half_to_even(3.7)
        4
        >>> round_half_to_even(4)
        4
        >>> round_half_to_even(4.2)
        4
        >>> round_half_to_even(4.5)
        4
        >>> round_half_to_even(4.7)
        5

    :param n:
    :return:
    """
    ten_n = 10 * n
    if ten_n == int(ten_n) and ten_n % 10 == 5:
        up = int(n + 0.5)
        down = int(n - 0.5)
        return up if up % 2 == 0 else down
    else:
        return int(round(n))
