from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic


class PermissionManager(models.Manager):
    def get_for_holder(self, holder):
        ct = ContentType.objects.get_for_model(holder)
        return [Permission.objects.get(id=id) for id in PermissionHolder.objects.filter(holder_type=ct,holder_id=holder.id).values_list('permission_id', flat=True)]

class Permission(models.Model):
    namespace = models.CharField(max_length=64, verbose_name=_(u'namespace'))
    name = models.CharField(max_length=64, verbose_name=_(u'name'))
    label = models.CharField(max_length=64, verbose_name=_(u'label'))

    objects = PermissionManager()
    
    class Meta:
        ordering = ('namespace', 'label')
        unique_together = ('namespace', 'name')
        verbose_name = _(u'permission')
        verbose_name_plural = _(u'permissions')

    def __unicode__(self):
        return self.label


class PermissionHolder(models.Model):
    permission = models.ForeignKey(Permission, verbose_name=_(u'permission'))
    holder_type = models.ForeignKey(ContentType, 
        related_name='permission_holder', 
        limit_choices_to = {'model__in': ('user', 'group', 'role')})
    holder_id = models.PositiveIntegerField()
    holder_object = generic.GenericForeignKey(ct_field='holder_type', fk_field='holder_id')

    class Meta:
        verbose_name = _(u'permission holder')
        verbose_name_plural = _(u'permission holders')
        
    def __unicode__(self):
        return unicode(self.holder_object)


class Role(models.Model):
    name = models.CharField(max_length=64, unique=True)
    label = models.CharField(max_length=64, unique=True, verbose_name=_(u'label'))
    
    class Meta:
        ordering = ('label',)
        verbose_name = _(u'role')
        verbose_name_plural = _(u'roles')

    def add_member(self, member):
        role_member, created = RoleMember.objects.get_or_create(
            role=self,
            member_type = ContentType.objects.get_for_model(member),
            member_id=member.id)
                
    def __unicode__(self):
        return self.label
   
    @models.permalink
    def get_absolute_url(self):
        return ('role_list',)


class RoleMember(models.Model):
    role = models.ForeignKey(Role, verbose_name=_(u'role'))
    member_type = models.ForeignKey(ContentType,
        related_name='role_member', 
        limit_choices_to = {'model__in': ('user', 'group')})
    member_id = models.PositiveIntegerField()
    member_object = generic.GenericForeignKey(ct_field='member_type', fk_field='member_id')

    class Meta:
        #ordering = ('label',)
        verbose_name = _(u'role member')
        verbose_name_plural = _(u'role members')
        
    def __unicode__(self):
        return unicode(self.member_object)