from django.conf import settings

try:
    from django.contrib.contenttypes.fields import GenericForeignKey
except ImportError:
    from django.contrib.contenttypes.generic import GenericForeignKey

from django.contrib.contenttypes.models import ContentType
from django.contrib.sites.models import Site
from django.core import urlresolvers
from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.utils import timezone
from django.utils.encoding import python_2_unicode_compatible

from django_comments.managers import CommentManager
from django_comments import get_model_name


COMMENT_MAX_LENGTH = getattr(settings, 'COMMENT_MAX_LENGTH', 3000)
ABSTRACT = getattr(settings, 'DJANGO_COMMENTS_ABSTRACT', False)


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")
    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)

    class Meta:
        abstract = True

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


@python_2_unicode_compatible
class Comment(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")
    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)
    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 = ABSTRACT
        db_table = "django_comments"
        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(Comment, 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


@python_2_unicode_compatible
class CommentFlag(models.Model):
    """
    Records a flag on a comment. This is intentionally flexible; right now, a
    flag could be:

        * A "removal suggestion" -- where a user suggests a comment for (potential) removal.

        * A "moderator deletion" -- used when a moderator deletes a comment.

    You can (ab)use this model to add other flags, if needed. However, by
    design users are only allowed to flag a comment with a given flag once;
    if you want rating look elsewhere.
    """
    user = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name=_('user'), related_name="comment_flags")
    comment = models.ForeignKey(get_model_name(), verbose_name=_('comment'), related_name="flags")
    flag = models.CharField(_('flag'), max_length=30, db_index=True)
    flag_date = models.DateTimeField(_('date'), default=None)

    # Constants for flag types
    SUGGEST_REMOVAL = "removal suggestion"
    MODERATOR_DELETION = "moderator deletion"
    MODERATOR_APPROVAL = "moderator approval"

    class Meta:
        db_table = 'django_comment_flags'
        unique_together = [('user', 'comment', 'flag')]
        verbose_name = _('comment flag')
        verbose_name_plural = _('comment flags')

    def __str__(self):
        return "%s flag of comment ID %s by %s" % (
            self.flag, self.comment_id, self.user.get_username()
        )

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