"""Default variable filters."""
from __future__ import unicode_literals

import random as random_module
import re
import warnings
from decimal import ROUND_HALF_UP, Context, Decimal, InvalidOperation
from functools import wraps
from pprint import pformat

from django.conf import settings
from django.utils import formats, six
from django.utils.dateformat import format, time_format
from django.utils.deprecation import RemovedInDjango110Warning
from django.utils.encoding import force_text, iri_to_uri
from django.utils.html import (
    avoid_wrapping, conditional_escape, escape, escapejs, linebreaks,
    remove_tags, strip_tags, urlize as _urlize,
)
from django.utils.http import urlquote
from django.utils.safestring import SafeData, mark_for_escaping, mark_safe
from django.utils.text import (
    Truncator, normalize_newlines, phone2numeric, slugify as _slugify, wrap,
)
from django.utils.timesince import timesince, timeuntil
from django.utils.translation import ugettext, ungettext

from .base import Variable, VariableDoesNotExist
from .library import Library

register = Library()


#######################
# STRING DECORATOR    #
#######################

def stringfilter(func):
    """
    Decorator for filters which should only receive unicode objects. The object
    passed as the first positional argument will be converted to a unicode
    object.
    """
    def _dec(*args, **kwargs):
        if args:
            args = list(args)
            args[0] = force_text(args[0])
            if (isinstance(args[0], SafeData) and
                    getattr(_dec._decorated_function, 'is_safe', False)):
                return mark_safe(func(*args, **kwargs))
        return func(*args, **kwargs)

    # Include a reference to the real function (used to check original
    # arguments by the template parser, and to bear the 'is_safe' attribute
    # when multiple decorators are applied).
    _dec._decorated_function = getattr(func, '_decorated_function', func)

    return wraps(func)(_dec)


###################
# STRINGS         #
###################

@register.filter(is_safe=True)
@stringfilter
def addslashes(value):
    """
    Adds slashes before quotes. Useful for escaping strings in CSV, for
    example. Less useful for escaping JavaScript; use the ``escapejs``
    filter instead.
    """
    return value.replace('\\', '\\\\').replace('"', '\\"').replace("'", "\\'")


@register.filter(is_safe=True)
@stringfilter
def capfirst(value):
    """Capitalizes the first character of the value."""
    return value and value[0].upper() + value[1:]


@register.filter("escapejs")
@stringfilter
def escapejs_filter(value):
    """Hex encodes characters for use in JavaScript strings."""
    return escapejs(value)


# Values for testing floatformat input against infinity and NaN representations,
# which differ across platforms and Python versions.  Some (i.e. old Windows
# ones) are not recognized by Decimal but we want to return them unchanged vs.
# returning an empty string as we do for completely invalid input.  Note these
# need to be built up from values that are not inf/nan, since inf/nan values do
# not reload properly from .pyc files on Windows prior to some level of Python 2.5
# (see Python Issue757815 and Issue1080440).
pos_inf = 1e200 * 1e200
neg_inf = -1e200 * 1e200
nan = (1e200 * 1e200) // (1e200 * 1e200)
special_floats = [str(pos_inf), str(neg_inf), str(nan)]


@register.filter(is_safe=True)
def floatformat(text, arg=-1):
    """
    Displays a float to a specified number of decimal places.

    If called without an argument, it displays the floating point number with
    one decimal place -- but only if there's a decimal place to be displayed:

    * num1 = 34.23234
    * num2 = 34.00000
    * num3 = 34.26000
    * {{ num1|floatformat }} displays "34.2"
    * {{ num2|floatformat }} displays "34"
    * {{ num3|floatformat }} displays "34.3"

    If arg is positive, it will always display exactly arg number of decimal
    places:

    * {{ num1|floatformat:3 }} displays "34.232"
    * {{ num2|floatformat:3 }} displays "34.000"
    * {{ num3|floatformat:3 }} displays "34.260"

    If arg is negative, it will display arg number of decimal places -- but
    only if there are places to be displayed:

    * {{ num1|floatformat:"-3" }} displays "34.232"
    * {{ num2|floatformat:"-3" }} displays "34"
    * {{ num3|floatformat:"-3" }} displays "34.260"

    If the input float is infinity or NaN, the (platform-dependent) string
    representation of that value will be displayed.
    """

    try:
        input_val = force_text(text)
        d = Decimal(input_val)
    except UnicodeEncodeError:
        return ''
    except InvalidOperation:
        if input_val in special_floats:
            return input_val
        try:
            d = Decimal(force_text(float(text)))
        except (ValueError, InvalidOperation, TypeError, UnicodeEncodeError):
            return ''
    try:
        p = int(arg)
    except ValueError:
        return input_val

    try:
        m = int(d) - d
    except (ValueError, OverflowError, InvalidOperation):
        return input_val

    if not m and p < 0:
        return mark_safe(formats.number_format('%d' % (int(d)), 0))

    if p == 0:
        exp = Decimal(1)
    else:
        exp = Decimal('1.0') / (Decimal(10) ** abs(p))
    try:
        # Set the precision high enough to avoid an exception, see #15789.
        tupl = d.as_tuple()
        units = len(tupl[1]) - tupl[2]
        prec = abs(p) + units + 1

        # Avoid conversion to scientific notation by accessing `sign`, `digits`
        # and `exponent` from `Decimal.as_tuple()` directly.
        sign, digits, exponent = d.quantize(exp, ROUND_HALF_UP,
            Context(prec=prec)).as_tuple()
        digits = [six.text_type(digit) for digit in reversed(digits)]
        while len(digits) <= abs(exponent):
            digits.append('0')
        digits.insert(-exponent, '.')
        if sign:
            digits.append('-')
        number = ''.join(reversed(digits))
        return mark_safe(formats.number_format(number, abs(p)))
    except InvalidOperation:
        return input_val


@register.filter(is_safe=True)
@stringfilter
def iriencode(value):
    """Escapes an IRI value for use in a URL."""
    return force_text(iri_to_uri(value))


@register.filter(is_safe=True, needs_autoescape=True)
@stringfilter
def linenumbers(value, autoescape=True):
    """Displays text with line numbers."""
    lines = value.split('\n')
    # Find the maximum width of the line count, for use with zero padding
    # string format command
    width = six.text_type(len(six.text_type(len(lines))))
    if not autoescape or isinstance(value, SafeData):
        for i, line in enumerate(lines):
            lines[i] = ("%0" + width + "d. %s") % (i + 1, line)
    else:
        for i, line in enumerate(lines):
            lines[i] = ("%0" + width + "d. %s") % (i + 1, escape(line))
    return mark_safe('\n'.join(lines))


@register.filter(is_safe=True)
@stringfilter
def lower(value):
    """Converts a string into all lowercase."""
    return value.lower()


@register.filter(is_safe=False)
@stringfilter
def make_list(value):
    """
    Returns the value turned into a list.

    For an integer, it's a list of digits.
    For a string, it's a list of characters.
    """
    return list(value)


@register.filter(is_safe=True)
@stringfilter
def slugify(value):
    """
    Converts to ASCII. Converts spaces to hyphens. Removes characters that
    aren't alphanumerics, underscores, or hyphens. Converts to lowercase.
    Also strips leading and trailing whitespace.
    """
    return _slugify(value)


@register.filter(is_safe=True)
def stringformat(value, arg):
    """
    Formats the variable according to the arg, a string formatting specifier.

    This specifier uses Python string formating syntax, with the exception that
    the leading "%" is dropped.

    See https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting
    for documentation of Python string formatting.
    """
    try:
        return ("%" + six.text_type(arg)) % value
    except (ValueError, TypeError):
        return ""


@register.filter(is_safe=True)
@stringfilter
def title(value):
    """Converts a string into titlecase."""
    t = re.sub("([a-z])'([A-Z])", lambda m: m.group(0).lower(), value.title())
    return re.sub("\d([A-Z])", lambda m: m.group(0).lower(), t)


@register.filter(is_safe=True)
@stringfilter
def truncatechars(value, arg):
    """
    Truncates a string after a certain number of characters.

    Argument: Number of characters to truncate after.
    """
    try:
        length = int(arg)
    except ValueError:  # Invalid literal for int().
        return value  # Fail silently.
    return Truncator(value).chars(length)


@register.filter(is_safe=True)
@stringfilter
def truncatechars_html(value, arg):
    """
    Truncates HTML after a certain number of chars.

    Argument: Number of chars to truncate after.

    Newlines in the HTML are preserved.
    """
    try:
        length = int(arg)
    except ValueError:  # invalid literal for int()
        return value  # Fail silently.
    return Truncator(value).chars(length, html=True)


@register.filter(is_safe=True)
@stringfilter
def truncatewords(value, arg):
    """
    Truncates a string after a certain number of words.

    Argument: Number of words to truncate after.

    Newlines within the string are removed.
    """
    try:
        length = int(arg)
    except ValueError:  # Invalid literal for int().
        return value  # Fail silently.
    return Truncator(value).words(length, truncate=' ...')


@register.filter(is_safe=True)
@stringfilter
def truncatewords_html(value, arg):
    """
    Truncates HTML after a certain number of words.

    Argument: Number of words to truncate after.

    Newlines in the HTML are preserved.
    """
    try:
        length = int(arg)
    except ValueError:  # invalid literal for int()
        return value  # Fail silently.
    return Truncator(value).words(length, html=True, truncate=' ...')


@register.filter(is_safe=False)
@stringfilter
def upper(value):
    """Converts a string into all uppercase."""
    return value.upper()


@register.filter(is_safe=False)
@stringfilter
def urlencode(value, safe=None):
    """
    Escapes a value for use in a URL.

    Takes an optional ``safe`` parameter used to determine the characters which