import codecs
import html
import re
import translitcodec  # provides 'translit/long', used by codecs.encode() # noqa

from django.conf import settings
from django.utils.encoding import force_str
from django.utils.functional import keep_lazy_text
from django.utils.html import mark_safe, strip_tags
from django.utils.text import slugify as django_slugify, normalize_newlines
from django.utils.translation import gettext_lazy


@keep_lazy_text
def downgrade(value):
    """
    Downgrade unicode to ascii, transliterating accented characters.
    """
    value = force_str(value or "")
    return codecs.encode(value, 'transliterate')


@keep_lazy_text
def slugify_long(value):
    return django_slugify(downgrade(value))


# Spreading umlauts is included in the translit/long codec.
slugify_german = slugify_long


@keep_lazy_text
def downgrading_slugify(value):
    # Slugfiy only allowing hyphens, numbers and ASCII characters
    # FIXME django_slugify might return an empty string; take care that we always return something
    return re.sub("[ _]+", "-", django_slugify(downgrade(value)))


SLUGIFY_FUNCTION = getattr(settings, 'SLUGIFY_FUNCTION', downgrading_slugify)
slugify = SLUGIFY_FUNCTION


@keep_lazy_text
def html_entities_to_unicode(html_str):
    return html.unescape(html_str)


# Translators: Separator between list elements
DEFAULT_SEPARATOR = gettext_lazy(", ")

# Translators: Last separator of list elements
LAST_WORD_SEPARATOR = gettext_lazy(" and ")


@keep_lazy_text
def text_joined(list_, separator=DEFAULT_SEPARATOR, last_word=LAST_WORD_SEPARATOR):
    list_ = list(list_)
    if len(list_) == 0:
        return ''
    if len(list_) == 1:
        return force_str(list_[0])
    return '%s%s%s' % (
        separator.join(force_str(i) for i in list_[:-1]),
        force_str(last_word), force_str(list_[-1]))


# TODO Don't match escaped stars (like \*)

b_pattern = re.compile(r"(\*\*)(.*?)\1")
i_pattern = re.compile(r"(\*)(.*?)\1")
u_pattern = re.compile(r"(__)(.*?)\1")
link_pattern = re.compile(r"\[([^\[]+)\]\(([^\)]+)\)")


@keep_lazy_text
def slimdown(text):
    """
    Converts simplified markdown (`**`, `*`, `__`) to <b>, <i> und <u> tags.
    """
    if text:
        text, n = re.subn(b_pattern, "<b>\\2</b>", text)
        text, n = re.subn(i_pattern, "<i>\\2</i>", text)
        text, n = re.subn(u_pattern, "<u>\\2</u>", text)
        text, n = re.subn(link_pattern, "<a href=\'\\2\'>\\1</a>", text)
        return mark_safe(text)
    else:
        return ""


@keep_lazy_text
def strip_links(text):
    return re.sub(r'<a[^>]+>', '', text, flags=re.DOTALL).replace('</a>', '')


COLLAPSE_WHITESPACE_RE = re.compile(r"\s+")


@keep_lazy_text
def collapse_whitespace(text):
    return COLLAPSE_WHITESPACE_RE.sub(" ", text).strip()


@keep_lazy_text
def html_to_text(text):
    print(text)
    rv = collapse_whitespace(strip_tags(html_entities_to_unicode(str(text))))
    print(rv)
    return rv


try:
    from html_sanitizer.django import get_sanitizer

    def sanitized_html(html, config_name='default'):
        return get_sanitizer(config_name).sanitize(html)
except ImportError:
    pass