from __future__ import unicode_literals

from operator import attrgetter

from django.apps import apps
from django.contrib.contenttypes.models import ContentType
from django.contrib.sessions.backends.db import SessionStore
from django.db.models import Count
from django.db.models.query_utils import deferred_class_factory, DeferredAttribute
from django.test import TestCase, override_settings

from .models import (
    ResolveThis, Item, RelatedItem, Child, Leaf, Proxy, SimpleItem, Feature,
    ItemAndSimpleItem, OneToOneItem, SpecialFeature, Location, Request,
    ProxyRelated, Derived, Base,
)


class DeferRegressionTest(TestCase):
    def test_basic(self):
        # Deferred fields should really be deferred and not accidentally use
        # the field's default value just because they aren't passed to __init__

        Item.objects.create(name="first", value=42)
        obj = Item.objects.only("name", "other_value").get(name="first")
        # Accessing "name" doesn't trigger a new database query. Accessing
        # "value" or "text" should.
        with self.assertNumQueries(0):
            self.assertEqual(obj.name, "first")
            self.assertEqual(obj.other_value, 0)

        with self.assertNumQueries(1):
            self.assertEqual(obj.value, 42)

        with self.assertNumQueries(1):
            self.assertEqual(obj.text, "xyzzy")

        with self.assertNumQueries(0):
            self.assertEqual(obj.text, "xyzzy")

        # Regression test for #10695. Make sure different instances don't
        # inadvertently share data in the deferred descriptor objects.
        i = Item.objects.create(name="no I'm first", value=37)
        items = Item.objects.only("value").order_by("-value")
        self.assertEqual(items[0].name, "first")
        self.assertEqual(items[1].name, "no I'm first")

        RelatedItem.objects.create(item=i)
        r = RelatedItem.objects.defer("item").get()
        self.assertEqual(r.item_id, i.id)
        self.assertEqual(r.item, i)

        # Some further checks for select_related() and inherited model
        # behavior (regression for #10710).
        c1 = Child.objects.create(name="c1", value=42)
        c2 = Child.objects.create(name="c2", value=37)
        Leaf.objects.create(name="l1", child=c1, second_child=c2)

        obj = Leaf.objects.only("name", "child").select_related()[0]
        self.assertEqual(obj.child.name, "c1")

        self.assertQuerysetEqual(
            Leaf.objects.select_related().only("child__name", "second_child__name"), [
                "l1",
            ],
            attrgetter("name")
        )

        # Models instances with deferred fields should still return the same
        # content types as their non-deferred versions (bug #10738).
        ctype = ContentType.objects.get_for_model
        c1 = ctype(Item.objects.all()[0])
        c2 = ctype(Item.objects.defer("name")[0])
        c3 = ctype(Item.objects.only("name")[0])
        self.assertTrue(c1 is c2 is c3)

        # Regression for #10733 - only() can be used on a model with two
        # foreign keys.
        results = Leaf.objects.only("name", "child", "second_child").select_related()
        self.assertEqual(results[0].child.name, "c1")
        self.assertEqual(results[0].second_child.name, "c2")

        results = Leaf.objects.only(
            "name", "child", "second_child", "child__name", "second_child__name"
        ).select_related()
        self.assertEqual(results[0].child.name, "c1")
        self.assertEqual(results[0].second_child.name, "c2")

        # Regression for #16409 - make sure defer() and only() work with annotate()
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count('feature')).defer('name')),
            list)
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count('feature')).only('name')),
            list)

    def test_ticket_11936(self):
        app_config = apps.get_app_config("defer_regress")
        # Regression for #11936 - get_models should not return deferred models
        # by default. Run a couple of defer queries so that app registry must
        # contain some deferred classes. It might contain a lot more classes
        # depending on the order the tests are ran.
        list(Item.objects.defer("name"))
        list(Child.objects.defer("value"))
        klasses = {model.__name__ for model in app_config.get_models()}
        self.assertIn("Child", klasses)
        self.assertIn("Item", klasses)
        self.assertNotIn("Child_Deferred_value", klasses)
        self.assertNotIn("Item_Deferred_name", klasses)
        self.assertFalse(any(k._deferred for k in app_config.get_models()))

        klasses_with_deferred = {model.__name__ for model in app_config.get_models(include_deferred=True)}
        self.assertIn("Child", klasses_with_deferred)
        self.assertIn("Item", klasses_with_deferred)
        self.assertIn("Child_Deferred_value", klasses_with_deferred)
        self.assertIn("Item_Deferred_name", klasses_with_deferred)
        self.assertTrue(any(k._deferred for k in app_config.get_models(include_deferred=True)))

    @override_settings(SESSION_SERIALIZER='django.contrib.sessions.serializers.PickleSerializer')
    def test_ticket_12163(self):
        # Test for #12163 - Pickling error saving session with unsaved model
        # instances.
        SESSION_KEY = '2b1189a188b44ad18c35e1baac6ceead'

        item = Item()
        item._deferred = False
        s = SessionStore(SESSION_KEY)
        s.clear()
        s["item"] = item
        s.save()

        s = SessionStore(SESSION_KEY)
        s.modified = True
        s.save()

        i2 = s["item"]
        self.assertFalse(i2._deferred)

    def test_ticket_16409(self):
        # Regression for #16409 - make sure defer() and only() work with annotate()
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count('feature')).defer('name')),
            list)
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count('feature')).only('name')),
            list)

    def test_ticket_23270(self):
        Derived.objects.create(text="foo", other_text="bar")
        with self.assertNumQueries(1):
            obj = Base.objects.select_related("derived").defer("text")[0]
            self.assertIsInstance(obj.derived, Derived)
            self.assertEqual("bar", obj.derived.other_text)
            self.assertNotIn("text", obj.__dict__)
            self.assertEqual(1, obj.derived.base_ptr_id)

    def test_only_and_defer_usage_on_proxy_models(self):
        # Regression for #15790 - only() broken for proxy models
        proxy = Proxy.objects.create(name="proxy", value=42)

        msg = 'QuerySet.only() return bogus results with proxy models'
        dp = Proxy.objects.only('other_value').get(pk=proxy.pk)
        self.assertEqual(dp.name, proxy.name, msg=msg)
        self.assertEqual(dp.value, proxy.value, msg=msg)

        # also test things with .defer()
        msg = 'QuerySet.defer() return bogus results with proxy models'
        dp = Proxy.objects.defer('name', 'text', 'value').get(pk=proxy.pk)
        self.assertEqual(dp.name, proxy.name, msg=msg)
        self.assertEqual(dp.value, proxy.value, msg=msg)

    def test_resolve_columns(self):
        ResolveThis.objects.create(num=5.0, name='Foobar')
        qs = ResolveThis.objects.defer('num')
        self.assertEqual(1, qs.count())
        self.assertEqual('Foobar', qs[0].name)

    def test_reverse_one_to_one_relations(self):
        # Refs #14694. Test reverse relations which are known unique (reverse
        # side has o2ofield or unique FK) - the o2o case
        item = Item.objects.create(name="first", value=42)
        o2o = OneToOneItem.objects.create(item=item, name="second")
        self.assertEqual(len(Item.objects.defer('one_to_one_item__name')), 1)
        self.assertEqual(len(Item.objects.select_related('one_to_one_item')), 1)
        self.assertEqual(len(Item.objects.select_related(
            'one_to_one_item').defer('one_to_one_item__name')), 1)
        self.assertEqual(len(Item.objects.select_related('one_to_one_item').defer('value')), 1)
        # Make sure that `only()` doesn't break when we pass in a unique relation,
        # rather than a field on the relation.
        self.assertEqual(len(Item.objects.only('one_to_one_item')), 1)
        with self.assertNumQueries(1):
            i = Item.objects.select_related('one_to_one_item')[0]
            self.assertEqual(i.one_to_one_item.pk, o2o.pk)
            self.assertEqual(i.one_to_one_item.name, "second")
        with self.assertNumQueries(1):
            i = Item.objects.select_related('one_to_one_item').defer(
                'value', 'one_to_one_item__name')[0]
            self.assertEqual(i.one_to_one_item.pk, o2o.pk)
            self.assertEqual(i.name, "first")
        with self.assertNumQueries(1):
            self.assertEqual(i.one_to_one_item.name, "second")
        with self.assertNumQueries(1):
            self.assertEqual(i.value, 42)

    def test_defer_with_select_related(self):
        item1 = Item.objects.create(name="first", value=47)
        item2 = Item.objects.create(name="second", value=42)
        simple = SimpleItem.objects.create(name="simple", value="23")
        ItemAndSimpleItem.objects.create(item=item1, simple=simple)

        obj = ItemAndSimpleItem.objects.defer('item').select_related('simple').get()
        self.assertEqual(obj.item, item1)
        self.assertEqual(obj.item_id, item1.id)

        obj.item = item2
        obj.save()

        obj = ItemAndSimpleItem.objects.defer('item').select_related('simple').get()
        self.assertEqual(obj.item, item2)
        self.assertEqual(obj.item_id, item2.id)

    def test_proxy_model_defer_with_selected_related(self):
        # Regression for #22050
        item = Item.objects.create(name="first", value=47)
        RelatedItem.objects.create(item=item)
        # Defer fields with only()
        obj = ProxyRelated.objects.all().select_related().only('item__name')[0]
        with self.assertNumQueries(0):
            self.assertEqual(obj.item.name, "first")
        with self.assertNumQueries(1):
            self.assertEqual(obj.item.value, 47)

    def test_only_with_select_related(self):
        # Test for #17485.
        item = SimpleItem.objects.create(name='first', value=47)
        feature = Feature.objects.create(item=item)
        SpecialFeature.objects.create(feature=feature)

        qs = Feature.objects.only('item__name').select_related('item')
        self.assertEqual(len(qs), 1)

        qs = SpecialFeature.objects.only('feature__item__name').select_related('feature__item')
        self.assertEqual(len(qs), 1)

    def test_deferred_class_factory(self):
        new_class = deferred_class_factory(
            Item,
            ('this_is_some_very_long_attribute_name_so_modelname_truncation_is_triggered',))
        self.assertEqual(
            new_class.__name__,
            'Item_Deferred_this_is_some_very_long_attribute_nac34b1f495507dad6b02e2cb235c875e')