from __future__ import unicode_literals

from django.conf import settings
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.contrib.sites.models import Site
from django.apps import apps
from django.utils.html import mark_safe
from django.db import models
from django.utils import timezone
from six import python_2_unicode_compatible
from django.utils.translation import gettext_lazy as _
try:
    from django.urls import reverse
except ImportError:
    from django.core.urlresolvers import reverse  # Django < 1.10

from .managers import CommentManager

COMMENT_MAX_LENGTH = getattr(settings, 'COMMENT_MAX_LENGTH', 3000)


class BaseCommentAbstractModel(models.Model):
    """
    An abstract base class that any custom comment models probably should
    subclass.
    """

    # Content-object field
    content_type = models.ForeignKey(ContentType,
                                     verbose_name=_('content type'),
                                     related_name="content_type_set_for_%(class)s",
                                     on_delete=models.CASCADE)
    object_pk = models.TextField(_('object ID'))
    content_object = GenericForeignKey(ct_field="content_type", fk_field="object_pk")

    # Metadata about the comment
    site = models.ForeignKey(Site, on_delete=models.CASCADE)

    class Meta:
        abstract = True

    def get_content_object_url(self):
        """
        Get a URL suitable for redirecting to the content object.
        """
        return reverse(
            "comments-url-redirect",
            args=(self.content_type_id, self.object_pk)
        )

    def get_object_url(self):
        ctype = self.content_type
        object_pk = self.object_pk
        model = apps.get_model(ctype.app_label, ctype.model)
        target = model.objects.get(pk=object_pk)
        return mark_safe("<a href='%s'>%s</a>" % (target.get_absolute_url(), target.title))
    get_object_url.short_description = "comment item"

@python_2_unicode_compatible
class CommentAbstractModel(BaseCommentAbstractModel):
    """
    A user comment about some object.
    """

    # Who posted this comment? If ``user`` is set then it was an authenticated
    # user; otherwise at least user_name should have been set and the comment
    # was posted by a non-authenticated user.
    user = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name=_('user'),
                             blank=True, null=True, related_name="%(class)s_comments",
                             on_delete=models.SET_NULL)
    user_name = models.CharField(_("user's name"), max_length=50, blank=True)
    # Explicit `max_length` to apply both to Django 1.7 and 1.8+.
    user_email = models.EmailField(_("user's email address"), max_length=254,
                                   blank=True)
    user_url = models.URLField(_("user's URL"), blank=True)

    comment = models.TextField(_('comment'), max_length=COMMENT_MAX_LENGTH)

    # Metadata about the comment
    submit_date = models.DateTimeField(_('date/time submitted'), default=None, db_index=True)
    ip_address = models.GenericIPAddressField(_('IP address'), unpack_ipv4=True, blank=True, null=True)
    is_public = models.BooleanField(_('is public'), default=True,
                                    help_text=_('Uncheck this box to make the comment effectively '
                                                'disappear from the site.'))
    is_removed = models.BooleanField(_('is removed'), default=False,
                                     help_text=_('Check this box if the comment is inappropriate. '
                                                 'A "This comment has been removed" message will '
                                                 'be displayed instead.'))

    # Manager
    objects = CommentManager()

    class Meta:
        abstract = True
        ordering = ('submit_date',)
        permissions = [("can_moderate", "Can moderate comments")]
        verbose_name = _('comment')
        verbose_name_plural = _('comments')

    def __str__(self):
        return "%s: %s..." % (self.name, self.comment[:50])

    def save(self, *args, **kwargs):
        if self.submit_date is None:
            self.submit_date = timezone.now()
        super(CommentAbstractModel, self).save(*args, **kwargs)

    def _get_userinfo(self):
        """
        Get a dictionary that pulls together information about the poster
        safely for both authenticated and non-authenticated comments.

        This dict will have ``name``, ``email``, and ``url`` fields.
        """
        if not hasattr(self, "_userinfo"):
            userinfo = {
                "name": self.user_name,
                "email": self.user_email,
                "url": self.user_url
            }
            if self.user_id:
                u = self.user
                if u.email:
                    userinfo["email"] = u.email

                # If the user has a full name, use that for the user name.
                # However, a given user_name overrides the raw user.username,
                # so only use that if this comment has no associated name.
                if u.get_full_name():
                    userinfo["name"] = self.user.get_full_name()
                elif not self.user_name:
                    userinfo["name"] = u.get_username()
            self._userinfo = userinfo
        return self._userinfo

    userinfo = property(_get_userinfo, doc=_get_userinfo.__doc__)

    def _get_name(self):
        return self.userinfo["name"]

    def _set_name(self, val):
        if self.user_id:
            raise AttributeError(_("This comment was posted by an authenticated "
                                   "user and thus the name is read-only."))
        self.user_name = val

    name = property(_get_name, _set_name, doc="The name of the user who posted this comment")

    def _get_email(self):
        return self.userinfo["email"]

    def _set_email(self, val):
        if self.user_id:
            raise AttributeError(_("This comment was posted by an authenticated "
                                   "user and thus the email is read-only."))
        self.user_email = val

    email = property(_get_email, _set_email, doc="The email of the user who posted this comment")

    def _get_url(self):
        return self.userinfo["url"]

    def _set_url(self, val):
        self.user_url = val

    url = property(_get_url, _set_url, doc="The URL given by the user who posted this comment")

    def get_absolute_url(self, anchor_pattern="#c%(id)s"):
        return self.get_content_object_url() + (anchor_pattern % self.__dict__)

    def get_as_text(self):
        """
        Return this comment as plain text.  Useful for emails.
        """
        d = {
            'user': self.user or self.name,
            'date': self.submit_date,
            'comment': self.comment,
            'domain': self.site.domain,
            'url': self.get_absolute_url()
        }
        return _('Posted by %(user)s at %(date)s\n\n%(comment)s\n\nhttp://%(domain)s%(url)s') % d