"""Humanizing functions for numbers."""
from __future__ import annotations

import math
import re
import sys
from fractions import Fraction
from typing import TYPE_CHECKING

from .i18n import _gettext as _
from .i18n import _ngettext, decimal_separator, thousands_separator
from .i18n import _ngettext_noop as NS_
from .i18n import _pgettext as P_

if TYPE_CHECKING:
    if sys.version_info >= (3, 10):
        from typing import TypeAlias
    else:
        from typing_extensions import TypeAlias

# This type can be better defined by typing.SupportsInt, typing.SupportsFloat
# but that's a Python 3.8 only typing option.
NumberOrString: TypeAlias = "float | str"


def _format_not_finite(value: float) -> str:
    """Utility function to handle infinite and nan cases."""
    if math.isnan(value):
        return "NaN"
    if math.isinf(value) and value < 0:
        return "-Inf"
    if math.isinf(value) and value > 0:
        return "+Inf"
    return ""


def ordinal(value: NumberOrString, gender: str = "male") -> str:
    """Converts an integer to its ordinal as a string.

    For example, 1 is "1st", 2 is "2nd", 3 is "3rd", etc. Works for any integer or
    anything `int()` will turn into an integer. Anything else will return the output
    of str(value).

    Examples:
        ```pycon
        >>> ordinal(1)
        '1st'
        >>> ordinal(1002)
        '1002nd'
        >>> ordinal(103)
        '103rd'
        >>> ordinal(4)
        '4th'
        >>> ordinal(12)
        '12th'
        >>> ordinal(101)
        '101st'
        >>> ordinal(111)
        '111th'
        >>> ordinal("something else")
        'something else'
        >>> ordinal([1, 2, 3]) == "[1, 2, 3]"
        True

        ```

    Args:
        value (int, str, float): Integer to convert.
        gender (str): Gender for translations. Accepts either "male" or "female".

    Returns:
        str: Ordinal string.
    """
    try:
        if not math.isfinite(float(value)):
            return _format_not_finite(float(value))
        value = int(value)
    except (TypeError, ValueError):
        return str(value)
    if gender == "male":
        t = (
            P_("0 (male)", "th"),
            P_("1 (male)", "st"),
            P_("2 (male)", "nd"),
            P_("3 (male)", "rd"),
            P_("4 (male)", "th"),
            P_("5 (male)", "th"),
            P_("6 (male)", "th"),
            P_("7 (male)", "th"),
            P_("8 (male)", "th"),
            P_("9 (male)", "th"),
        )
    else:
        t = (
            P_("0 (female)", "th"),
            P_("1 (female)", "st"),
            P_("2 (female)", "nd"),
            P_("3 (female)", "rd"),
            P_("4 (female)", "th"),
            P_("5 (female)", "th"),
            P_("6 (female)", "th"),
            P_("7 (female)", "th"),
            P_("8 (female)", "th"),
            P_("9 (female)", "th"),
        )
    if value % 100 in (11, 12, 13):  # special case
        return f"{value}{t[0]}"
    return f"{value}{t[value % 10]}"


def intcomma(value: NumberOrString, ndigits: int | None = None) -> str:
    """Converts an integer to a string containing commas every three digits.

    For example, 3000 becomes "3,000" and 45000 becomes "45,000". To maintain some
    compatibility with Django's `intcomma`, this function also accepts floats.

    Examples:
        ```pycon
        >>> intcomma(100)
        '100'
        >>> intcomma("1000")
        '1,000'
        >>> intcomma(1_000_000)
        '1,000,000'
        >>> intcomma(1_234_567.25)
        '1,234,567.25'
        >>> intcomma(1234.5454545, 2)
        '1,234.55'
        >>> intcomma(14308.40, 1)
        '14,308.4'
        >>> intcomma("14308.40", 1)
        '14,308.4'
        >>> intcomma(None)
        'None'

        ```

    Args:
        value (int, float, str): Integer or float to convert.
        ndigits (int, None): Digits of precision for rounding after the decimal point.

    Returns:
        str: String containing commas every three digits.
    """
    thousands_sep = thousands_separator()
    decimal_sep = decimal_separator()
    try:
        if isinstance(value, str):
            value = value.replace(thousands_sep, "").replace(decimal_sep, ".")
            if not math.isfinite(float(value)):
                return _format_not_finite(float(value))
            if "." in value:
                value = float(value)
            else:
                value = int(value)
        else:
            if not math.isfinite(float(value)):
                return _format_not_finite(float(value))
            float(value)
    except (TypeError, ValueError):
        return str(value)

    if ndigits is not None:
        orig = "{0:.{1}f}".format(value, ndigits)
    else:
        orig = str(value)
    orig = orig.replace(".", decimal_sep)
    while True:
        new = re.sub(r"^(-?\d+)(\d{3})", rf"\g<1>{thousands_sep}\g<2>", orig)
        if orig == new:
            return new
        orig = new


powers = [10**x for x in (3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 100)]
human_powers = (
    NS_("thousand", "thousand"),
    NS_("million", "million"),
    NS_("billion", "billion"),
    NS_("trillion", "trillion"),
    NS_("quadrillion", "quadrillion"),
    NS_("quintillion", "quintillion"),
    NS_("sextillion", "sextillion"),
    NS_("septillion", "septillion"),
    NS_("octillion", "octillion"),
    NS_("nonillion", "nonillion"),
    NS_("decillion", "decillion"),
    NS_("googol", "googol"),
)


def intword(value: NumberOrString, format: str = "%.1f") -> str:
    """Converts a large integer to a friendly text representation.

    Works best for numbers over 1 million. For example, 1_000_000 becomes "1.0 million",
    1200000 becomes "1.2 million" and "1_200_000_000" becomes "1.2 billion". Supports up
    to decillion (33 digits) and googol (100 digits).

    Examples:
        ```pycon
        >>> intword("100")
        '100'
        >>> intword("12400")
        '12.4 thousand'
        >>> intword("1000000")
        '1.0 million'
        >>> intword(1_200_000_000)
        '1.2 billion'
        >>> intword(8100000000000000000000000000000000)
        '8.1 decillion'
        >>> intword(None)
        'None'
        >>> intword("1234000", "%0.3f")
        '1.234 million'

        ```

    Args:
        value (int, float, str): Integer to convert.
        format (str): To change the number of decimal or general format of the number
            portion.

    Returns:
        str: Friendly text representation as a string, unless the value passed could not
            be coaxed into an `int`.
    """
    try:
        if not math.isfinite(float(value)):
            return _format_not_finite(float(value))
        value = int(value)
    except (TypeError, ValueError):
        return str(value)

    if value < 0:
        value *= -1
        negative_prefix = "-"
    else:
        negative_prefix = ""

    if value < powers[0]:
        return negative_prefix + str(value)

    for ordinal_, power in enumerate(powers[1:], 1):
        if value < power:
            chopped = value / float(powers[ordinal_ - 1])
            powers_difference = powers[ordinal_] / powers[ordinal_ - 1]
            if float(format % chopped) == powers_difference:
                chopped = value / float(powers[ordinal_])
                singular, plural = human_powers[ordinal_]
                return (
                    negative_prefix
                    + " ".join(
                        [format, _ngettext(singular, plural, math.ceil(chopped))]
                    )
                ) % chopped

            singular, plural = human_powers[ordinal_ - 1]
            return (
                negative_prefix
                + " ".join([format, _ngettext(singular, plural, math.ceil(chopped))])
            ) % chopped

    return negative_prefix + str(value)


def apnumber(value: NumberOrString) -> str:
    """Converts an integer to Associated Press style.

    Examples:
      ```pycon
      >>> apnumber(0)
      'zero'
      >>> apnumber(5)
      'five'
      >>> apnumber(10)
      '10'
      >>> apnumber("7")
      'seven'
      >>> apnumber("foo")
      'foo'
      >>> apnumber(None)
      'None'

      ```

    Args:
        value (int, float, str): Integer to convert.

    Returns:
        str: For numbers 0-9, the number spelled out. Otherwise, the number. This always
            returns a string unless the value was not `int`-able, then `str(value)`
            is returned.
    """
    try:
        if not math.isfinite(float(value)):
            return _format_not_finite(float(value))
        value = int(value)
    except (TypeError, ValueError):
        return str(value)
    if not 0 <= value < 10:
        return str(value)
    return (
        _("zero"),
        _("one"),
        _("two"),
        _("three"),
        _("four"),
        _("five"),
        _("six"),
        _("seven"),
        _("eight"),
        _("nine"),
    )[value]


def fractional(value: NumberOrString) -> str:
    """Convert to fractional number.

    There will be some cases where one might not want to show ugly decimal places for
    floats and decimals.

    This function returns a human-readable fractional number in form of fractions and
    mixed fractions.

    Pass in a string, or a number or a float, and this function returns:

    * a string representation of a fraction
    * or a whole number
    * or a mixed fraction
    * or the str output of the value, if it could not be converted

    Examples:
        ```pycon
        >>> fractional(0.3)
        '3/10'
        >>> fractional(1.3)
        '1 3/10'
        >>> fractional(float(1/3))
        '1/3'
        >>> fractional(1)
        '1'
        >>> fractional("ten")
        'ten'
        >>> fractional(None)
        'None'

        ```

    Args:
        value (int, float, str): Integer to convert.

    Returns:
        str: Fractional number as a string.
    """
    try:
        number = float(value)
        if not math.isfinite(number):
            return _format_not_finite(number)
    except (TypeError, ValueError):
        return str(value)
    whole_number = int(number)
    frac = Fraction(number - whole_number).limit_denominator(1000)
    numerator = frac.numerator
    denominator = frac.denominator
    if whole_number and not numerator and denominator == 1:
        # this means that an integer was passed in
        # (or variants of that integer like 1.0000)
        return f"{whole_number:.0f}"

    if not whole_number:
        return f"{numerator:.0f}/{denominator:.0f}"

    return f"{whole_number:.0f} {numerator:.0f}/{denominator:.0f}"


def scientific(value: NumberOrString, precision: int = 2) -> str:
    """Return number in string scientific notation z.wq x 10ⁿ.

    Examples:
        ```pycon
        >>> scientific(float(0.3))
        '3.00 x 10⁻¹'
        >>> scientific(int(500))
        '5.00 x 10²'
        >>> scientific(-1000)
        '-1.00 x 10³'
        >>> scientific(1000, 1)
        '1.0 x 10³'
        >>> scientific(1000, 3)
        '1.000 x 10³'
        >>> scientific("99")
        '9.90 x 10¹'
        >>> scientific("foo")
        'foo'
        >>> scientific(None)
        'None'

        ```

    Args:
        value (int, float, str): Input number.
        precision (int): Number of decimal for first part of the number.

    Returns:
        str: Number in scientific notation z.wq x 10ⁿ.
    """
    exponents = {
        "0": "⁰",
        "1": "¹",
        "2": "²",
        "3": "³",
        "4": "⁴",
        "5": "⁵",
        "6": "⁶",
        "7": "⁷",
        "8": "⁸",
        "9": "⁹",
        "-": "⁻",
    }
    try:
        value = float(value)
        if not math.isfinite(value):
            return _format_not_finite(value)
    except (ValueError, TypeError):
        return str(value)
    fmt = "{:.%se}" % str(int(precision))
    n = fmt.format(value)
    part1, part2 = n.split("e")
    # Remove redundant leading '+' or '0's (preserving the last '0' for 10⁰).
    part2 = re.sub(r"^\+?(\-?)0*(.+)$", r"\1\2", part2)

    new_part2 = []
    for char in part2:
        new_part2.append(exponents[char])

    final_str = part1 + " x 10" + "".join(new_part2)

    return final_str


def clamp(
    value: float,
    format: str = "{:}",
    floor: float | None = None,
    ceil: float | None = None,
    floor_token: str = "<",
    ceil_token: str = ">",
) -> str:
    """Returns number with the specified format, clamped between floor and ceil.

    If the number is larger than ceil or smaller than floor, then the respective limit
    will be returned, formatted and prepended with a token specifying as such.

    Examples:
        ```pycon
        >>> clamp(123.456)
        '123.456'
        >>> clamp(0.0001, floor=0.01)
        '<0.01'
        >>> clamp(0.99, format="{:.0%}", ceil=0.99)
        '99%'
        >>> clamp(0.999, format="{:.0%}", ceil=0.99)
        '>99%'
        >>> clamp(1, format=intword, floor=1e6, floor_token="under ")
        'under 1.0 million'
        >>> clamp(None) is None
        True

        ```

    Args:
        value (int, float): Input number.
        format (str OR callable): Can either be a formatting string, or a callable
            function that receives value and returns a string.
        floor (int, float): Smallest value before clamping.
        ceil (int, float): Largest value before clamping.
        floor_token (str): If value is smaller than floor, token will be prepended
            to output.
        ceil_token (str): If value is larger than ceil, token will be prepended
            to output.

    Returns:
        str: Formatted number. The output is clamped between the indicated floor and
            ceil. If the number is larger than ceil or smaller than floor, the output
            will be prepended with a token indicating as such.

    """
    if value is None:
        return None

    if not math.isfinite(value):
        return _format_not_finite(value)

    if floor is not None and value < floor:
        value = floor
        token = floor_token
    elif ceil is not None and value > ceil:
        value = ceil
        token = ceil_token
    else:
        token = ""

    if isinstance(format, str):
        return token + format.format(value)

    if callable(format):
        return token + format(value)

    msg = (
        "Invalid format. Must be either a valid formatting string, or a function "
        "that accepts value and returns a string."
    )
    raise ValueError(msg)


def metric(value: float, unit: str = "", precision: int = 3) -> str:
    """Return a value with a metric SI unit-prefix appended.

    Examples:
        ```pycon
        >>> metric(1500, "V")
        '1.50 kV'
        >>> metric(2e8, "W")
        '200 MW'
        >>> metric(220e-6, "F")
        '220 μF'
        >>> metric(1e-14, precision=4)
        '10.00 f'

        ```

    The unit prefix is always chosen so that non-significant zero digits are required.
    i.e. `123,000` will become `123k` instead of `0.123M` and `1,230,000` will become
    `1.23M` instead of `1230K`. For numbers that are either too huge or too tiny to
    represent without resorting to either leading or trailing zeroes, it falls back to
    `scientific()`.
    ```pycon
    >>> metric(1e40)
    '1.00 x 10⁴⁰'

    ```

    Args:
        value (int, float): Input number.
        unit (str): Optional base unit.
        precision (int): The number of digits the output should contain.

    Returns:
        str:
    """
    if not math.isfinite(value):
        return _format_not_finite(value)
    exponent = int(math.floor(math.log10(abs(value)))) if value != 0 else 0

    if exponent >= 33 or exponent < -30:
        return scientific(value, precision - 1) + unit

    value /= 10 ** (exponent // 3 * 3)
    if exponent >= 3:
        ordinal_ = "kMGTPEZYRQ"[exponent // 3 - 1]
    elif exponent < 0:
        ordinal_ = "mμnpfazyrq"[(-exponent - 1) // 3]
    else:
        ordinal_ = ""
    value_ = format(value, ".%if" % (precision - (exponent % 3) - 1))
    if not (unit or ordinal_) or unit in ("°", "′", "″"):
        space = ""
    else:
        space = " "

    return f"{value_}{space}{ordinal_}{unit}"