Glamping-Hub/django-painless-seo

# Copyright (C) 2014 Glamping Hub (https://glampinghub.com)
# License: BSD 3-Clause

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

from django.contrib.contenttypes.models import ContentType
from django.contrib.sites.models import Site
from django.core.exceptions import ImproperlyConfigured
from django.db import models
from django.utils.translation import activate, get_language
from django.utils.translation import ugettext_lazy as _

from . import settings


class SeoMetadata(models.Model):
    content_type = models.ForeignKey(
        ContentType, null=True, blank=True)

    object_id = models.PositiveIntegerField(
        null=True, blank=True)

    content_object = GenericForeignKey(
        'content_type', 'object_id')

    path = models.CharField(
        verbose_name=_('Path'), max_length=200, db_index=True,
        help_text=_('This should be an absolute path, excluding the domain '
                    'name. Example: \'/foo/bar/\'.'))

    lang_code = models.CharField(
        verbose_name=_('Language'), max_length=2,
        choices=settings.SEO_LANGUAGES, default=settings.DEFAULT_LANG_CODE)

    title = models.CharField(
        verbose_name=_('Title'), max_length=68, blank=True)

    description = models.CharField(
        verbose_name=_('Description'), max_length=155, blank=True)

    site = models.ForeignKey(
        Site, verbose_name=_('Site'), related_name='seo_metadata', null=True,
        blank=True, default=None)

    class Meta:
        verbose_name = _('SEO metadata')
        verbose_name_plural = _('SEO metadata')
        db_table = 'seo_metadata'
        unique_together = (('path', 'lang_code', 'site'), )
        ordering = ('path', 'lang_code', 'site')

    def __unicode__(self):
        return "Language: %s | URL: %s" % (self.lang_code, self.path)


def update_seo(sender, instance, **kwargs):
    active_lang = get_language()
    sites = Site.objects.all()
    for lang_code, lang_name in settings.SEO_LANGUAGES:
        activate(lang_code)
        for site in sites:
            try:
                sm = SeoMetadata.objects.get(
                    content_type=ContentType.objects.get_for_model(instance),
                    object_id=instance.id, lang_code=lang_code, site=site)
                if instance.get_absolute_url() != sm.path:
                    sm.path = instance.get_absolute_url()
            except SeoMetadata.DoesNotExist:
                sm = SeoMetadata(
                    lang_code=lang_code, content_object=instance,
                    path=instance.get_absolute_url(), site=site)
            sm.save()
    activate(active_lang)


def delete_seo(sender, instance, **kwargs):
    ctype = ContentType.objects.get_for_model(instance)
    SeoMetadata.objects.filter(
        content_type=ctype, object_id=instance.id).delete()


def register_seo_signals():
    for app, model in settings.SEO_MODELS:
        ctype = ContentType.objects.get(app_label=app, model=model)
        if not hasattr(ctype.model_class(), 'get_absolute_url'):
            raise ImproperlyConfigured(
                'Needed \'get_absolute_url\' method not defined on \'%s.%s\' '
                'model.' % (app, model))
        models.signals.post_save.connect(
            update_seo, sender=ctype.model_class(), weak=False)
        models.signals.pre_delete.connect(
            delete_seo, sender=ctype.model_class(), weak=False)