from __future__ import absolute_import

import logging

from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.utils.translation import ugettext
from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.models import User
from django.core.exceptions import PermissionDenied

from common.models import AnonymousUserSingleton

from .classes import EncapsulatedObject, AccessHolder, ClassAccessHolder

logger = logging.getLogger(__name__)


class AccessEntryManager(models.Manager):
    def source_object(self, obj):
        if isinstance(obj, EncapsulatedObject):
            return obj.source_object
        else:
            return obj
        
    def grant(self, permission, actor, obj):
        '''
        Grant a permission (what), (to) an actor, (on) a specific object
        '''
        obj = self.source_object(obj)
        actor = self.source_object(actor)
        
        access_entry, created = self.model.objects.get_or_create(
            permission=permission,
            holder_type=ContentType.objects.get_for_model(actor),
            holder_id=actor.pk,
            content_type=ContentType.objects.get_for_model(obj),
            object_id=obj.pk
        )
        return created

    def revoke(self, permission, actor, obj):
        '''
        Revoke a permission (what), (from) an actor, (on) a specific object
        '''        
        obj = self.source_object(obj)
        actor = self.source_object(actor)

        try:
            access_entry = self.model.objects.get(
                permission=permission,
                holder_type=ContentType.objects.get_for_model(actor),
                holder_id=actor.pk,
                content_type=ContentType.objects.get_for_model(obj),
                object_id=obj.pk
            )
            access_entry.delete()
            return True
        except self.model.DoesNotExist:
            return False		

    def has_access(self, permission, actor, obj):
        obj = self.source_object(obj)
        actor = self.source_object(actor)
        
        if isinstance(actor, User):
            if actor.is_superuser or actor.is_staff:
                return True

        actor = AnonymousUserSingleton.objects.passthru_check(actor)

        try:
            access_entry = self.model.objects.get(
                permission=permission.get_stored_permission(),
                holder_type=ContentType.objects.get_for_model(actor),
                holder_id=actor.pk,
                content_type=ContentType.objects.get_for_model(obj),
                object_id=obj.pk
            )
            return True
        except self.model.DoesNotExist:
            return False
                
    def check_access(self, permission, actor, obj):
        obj = self.source_object(obj)
        actor = self.source_object(actor)

        if self.has_access(permission, actor, obj):
            return True
        else:
            raise PermissionDenied(ugettext(u'Insufficient access.'))
            
    def check_accesses(self, permission_list, actor, obj):
        obj = self.source_object(obj)
        actor = self.source_object(actor)
        for permission in permission_list:
            if self.has_access(permission, actor, obj):
                return True

        raise PermissionDenied(ugettext(u'Insufficient access.'))

    def get_allowed_class_objects(self, permission, actor, cls, related=None):
        logger.debug('related: %s' % related)
        
        actor = AnonymousUserSingleton.objects.passthru_check(actor)
        actor_type = ContentType.objects.get_for_model(actor)
        content_type = ContentType.objects.get_for_model(cls)
        if related:
            master_list = [obj.content_object for obj in self.model.objects.select_related().filter(holder_type=actor_type, holder_id=actor.pk, permission=permission.get_stored_permission)]
            logger.debug('master_list: %s' % master_list)
            # TODO: update to use Q objects and check performance diff
            # kwargs = {'%s__in' % related: master_list}
            # Q(**kwargs)
            return (obj for obj in cls.objects.all() if getattr(obj, related) in master_list)
        else:
            return (obj.content_object for obj in self.model.objects.filter(holder_type=actor_type, holder_id=actor.pk, content_type=content_type, permission=permission.get_stored_permission))

    def get_acl_url(self, obj):
        content_type = ContentType.objects.get_for_model(obj)
        return reverse('acl_list', args=[content_type.app_label, content_type.model, obj.pk])

    def get_new_holder_url(self, obj):
        content_type = ContentType.objects.get_for_model(obj)
        return reverse('acl_new_holder_for', args=[content_type.app_label, content_type.model, obj.pk])
        
    def get_holders_for(self, obj):
        content_type = ContentType.objects.get_for_model(obj)
        holder_list = []
        for access_entry in self.model.objects.filter(content_type=content_type, object_id=obj.pk):
            entry = AccessHolder.encapsulate(access_entry.holder_object)
            
            if entry not in holder_list:
                holder_list.append(entry)
        
        return holder_list

    def get_holder_permissions_for(self, obj, actor):
        logger.debug('obj: %s' % obj)
        logger.debug('actor: %s' % actor)
        
        if isinstance(actor, User):
            if actor.is_superuser or actor.is_staff:
                return Permission.objects.all()

        actor_type = ContentType.objects.get_for_model(actor)
        content_type = ContentType.objects.get_for_model(obj)
        return (access.permission for access in self.model.objects.filter(content_type=content_type, object_id=obj.pk, holder_type=actor_type, holder_id=actor.pk))

    def filter_objects_by_access(self, permission, actor, object_list, exception_on_empty=False, related=None):
        logger.debug('exception_on_empty: %s' % exception_on_empty)
        logger.debug('object_list: %s' % object_list)
        
        if isinstance(actor, User):
            if actor.is_superuser or actor.is_staff:
                return object_list
        
        try:
            if object_list.count() == 0:
                return object_list
        except TypeError:
            # object_list is not a queryset
            if len(object_list) == 0:
                return object_list
        
        try:
            # Try to process as a QuerySet
            qs = object_list.filter(pk__in=[obj.pk for obj in self.get_allowed_class_objects(permission, actor, object_list[0].__class__, related)])
            logger.debug('qs: %s' % qs)
            
            if qs.count() == 0 and exception_on_empty == True:
                raise PermissionDenied
            
            return qs
        except AttributeError:
            # Fallback to a filtered list
            object_list = list(set(object_list) & set(self.get_allowed_class_objects(permission, actor, object_list[0].__class__, related)))
            logger.debug('object_list: %s' % object_list)
            if len(object_list) == 0 and exception_on_empty == True:
                raise PermissionDenied

            return object_list


class DefaultAccessEntryManager(models.Manager):
    def get_holders_for(self, cls):
        if isinstance(cls, EncapsulatedObject):
            cls = cls.source_object

        content_type = ContentType.objects.get_for_model(cls)
        holder_list = []
        for access_entry in self.model.objects.filter(content_type=content_type):
            entry = ClassAccessHolder.encapsulate(access_entry.holder_object)
            
            if entry not in holder_list:
                holder_list.append(entry)
        
        return holder_list

    def has_access(self, permission, actor, cls):
        if isinstance(actor, User):
            if actor.is_superuser or actor.is_staff:
                return True
                        
        try:
            access_entry = self.model.objects.get(
                permission=permission.get_stored_permission(),
                holder_type=ContentType.objects.get_for_model(actor),
                holder_id=actor.pk,
                content_type=ContentType.objects.get_for_model(cls),
            )
            return True
        except self.model.DoesNotExist:
            return False

    def grant(self, permission, actor, cls):
        '''
        Grant a permission (what), (to) an actor, (on) a specific class
        '''
        access_entry, created = self.model.objects.get_or_create(
            permission=permission,
            holder_type=ContentType.objects.get_for_model(actor),
            holder_id=actor.pk,
            content_type=ContentType.objects.get_for_model(cls),
        )
        return created

    def revoke(self, permission, actor, cls):
        '''
        Revoke a permission (what), (from) an actor, (on) a specific class
        '''        
        try:
            access_entry = self.model.objects.get(
                permission=permission,
                holder_type=ContentType.objects.get_for_model(actor),
                holder_id=actor.pk,
                content_type=ContentType.objects.get_for_model(cls),
            )
            access_entry.delete()
            return True
        except self.model.DoesNotExist:
            return False		

    def get_holder_permissions_for(self, cls, actor):
        if isinstance(actor, User):
            if actor.is_superuser or actor.is_staff:
                return Permission.objects.all()
                        
        actor_type = ContentType.objects.get_for_model(actor)
        content_type = ContentType.objects.get_for_model(cls)
        return [access.permission for access in self.model.objects.filter(content_type=content_type, holder_type=actor_type, holder_id=actor.pk)]