# publik-django-templatetags
# Copyright (C) 2022  Entr'ouvert
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import math
from decimal import Decimal
from decimal import DivisionByZero as DecimalDivisionByZero
from decimal import InvalidOperation as DecimalInvalidOperation

from django import template
from django.template import defaultfilters
from django.utils.encoding import force_text

register = template.Library()


@register.filter(name='get')
def get(obj, key):
    try:
        return obj.get(key)
    except AttributeError:
        try:
            return obj[key]
        except (IndexError, KeyError, TypeError):
            return None


@register.filter
def getlist(mapping, key):
    if mapping is None:
        return []
    mapping = list(mapping)
    for value in mapping:
        try:
            yield value.get(key)
        except AttributeError:
            yield None


@register.filter(name='list')
def as_list(obj):
    return list(obj)


@register.filter
def split(string, separator=' '):
    return (force_text(string) or '').split(separator)


@register.filter
def first(value):
    try:
        return defaultfilters.first(value)
    except TypeError:
        return ''


@register.filter
def last(value):
    try:
        return defaultfilters.last(value)
    except TypeError:
        return ''


def parse_decimal(value, default=Decimal(0)):
    if isinstance(value, str):
        # replace , by . for French users comfort
        value = value.replace(',', '.')
    try:
        return Decimal(value).quantize(Decimal('1.0000')).normalize()
    except (ArithmeticError, TypeError):
        return default


@register.filter(is_safe=False)
def decimal(value, arg=None):
    if not isinstance(value, Decimal):
        value = parse_decimal(value)
    if arg is None:
        return value
    return defaultfilters.floatformat(value, arg=arg)


@register.filter
def add(term1, term2):
    '''replace the "add" native django filter'''

    if term1 is None:
        term1 = ''
    if term2 is None:
        term2 = ''
    term1_decimal = parse_decimal(term1, default=None)
    term2_decimal = parse_decimal(term2, default=None)

    if term1_decimal is not None and term2_decimal is not None:
        return term1_decimal + term2_decimal
    if term1 == '' and term2_decimal is not None:
        return term2_decimal
    if term2 == '' and term1_decimal is not None:
        return term1_decimal
    return defaultfilters.add(term1, term2)


@register.filter
def subtract(term1, term2):
    return parse_decimal(term1) - parse_decimal(term2)


@register.filter
def multiply(term1, term2):
    return parse_decimal(term1) * parse_decimal(term2)


@register.filter
def divide(term1, term2):
    try:
        return parse_decimal(term1) / parse_decimal(term2)
    except DecimalInvalidOperation:
        return ''
    except DecimalDivisionByZero:
        return ''


@register.filter
def ceil(value):
    '''the smallest integer value greater than or equal to value'''
    return decimal(math.ceil(parse_decimal(value)))


@register.filter
def floor(value):
    return decimal(math.floor(parse_decimal(value)))


@register.filter(name='abs')
def abs_(value):
    return decimal(abs(parse_decimal(value)))


@register.filter(name='sum')
def sum_(list_):
    if isinstance(list_, str):
        # do not consider string as iterable, to avoid misusage
        return ''
    try:
        return sum(parse_decimal(term) for term in list_)
    except TypeError:  # list_ is not iterable
        return ''