from functools import reduce, partial
from django.conf import settings
from django.db import models
from django.utils.html import strip_tags
from django.utils.text import normalize_newlines
from django.utils.translation import ugettext_lazy as _

from shared.utils.fields import AutoSlugField
from shared.utils.functional import firstof
from shared.utils.text import slimdown

from . import USE_TRANSLATABLE_FIELDS


if USE_TRANSLATABLE_FIELDS:
    from shared.multilingual.utils.fields import TranslatableCharField, TranslatableTextField


class PageTitlesMixin(models.Model):
    """
    A model mixin containg title and slug field for models serving as website
    pages with an URL.
    """
    # FIXME signals are not sent from abstract models, therefore AutoSlugField doesn't work
    if USE_TRANSLATABLE_FIELDS:
        short_title = TranslatableCharField(_("Name"), max_length=50)
        title = TranslatableTextField(_("Titel (Langform)"), null=True, blank=True, max_length=300)
        window_title = TranslatableCharField(_("Fenster-/Suchmaschinentitel"), null=True, blank=True, max_length=300)
        # FIXME populate_from should use settings.LANGUAGE
        slug = AutoSlugField(_("URL-Name"), max_length=200, populate_from='short_title_de', unique_slug=True, blank=True)

    else:
        short_title = models.CharField(_("Name"), max_length=50)
        title = models.TextField(_("Titel (Langform)"), null=True, blank=True, max_length=300)
        window_title = models.CharField(_("Fenster-/Suchmaschinentitel"), null=True, blank=True, max_length=300)
        slug = AutoSlugField(_("URL-Name"), max_length=200, populate_from='short_title', unique_slug=True, blank=True)

    class Meta:
        abstract = True

    def __str__(self):
        return strip_tags(slimdown(self.short_title))

    def get_title(self):
        return slimdown(firstof(
            self.title,
            self.short_title
        ))

    def get_window_title(self):
        return strip_tags(slimdown(
            firstof(
                self.window_title,
                self.short_title,
                self.get_first_title_line(),
            )
        ))

    def get_first_title_line(self):
        """
        First line of title field.
        """
        return slimdown(
            normalize_newlines(self.get_title()).partition("\n")[0]
        )

    def get_subtitle_lines(self):
        """
        All but first line of the long title field.
        """
        return slimdown(
            normalize_newlines(self.title).partition("\n")[2]
        )


# TODO Move to shared.multilingual or shared.utils.translation
def language_variations_for_field(language_codes, fields):
    # TODO Check if field is translatable
    return ["{}_{}".format(fields, s) for s in language_codes]


# TODO Move to shared.multilingual or shared.utils.translation
def language_variations_for_fields(fields, language_codes=None):
    if not language_codes:
        language_codes = [t[0] for t in settings.LANGUAGES]
    f = partial(language_variations_for_field, language_codes)
    return reduce(lambda x, y: x + y, map(f, fields))


class PageTitleAdminMixin(object):
    search_fields = ['short_title', 'title', 'window_title']
    if USE_TRANSLATABLE_FIELDS:
        search_fields = language_variations_for_fields(search_fields)
    list_display = ['short_title', 'slug']
    prepopulated_fields = {
        'slug': ('short_title_en',),
    }