from datetime import datetime
from operator import attrgetter

from django.core.exceptions import FieldError
from django.db.models import (
    Case,
    CharField,
    Count,
    DateTimeField,
    F,
    IntegerField,
    Max,
    OrderBy,
    OuterRef,
    Subquery,
    Value,
    When,
)
from django.db.models.functions import Length, Upper
from django.test import TestCase

from .models import (
    Article,
    Author,
    ChildArticle,
    OrderedByExpression,
    OrderedByExpressionChild,
    OrderedByExpressionGrandChild,
    OrderedByFArticle,
    Reference,
)


class OrderingTests(TestCase):
    @classmethod
    def setUpTestData(cls):
        cls.a1 = Article.objects.create(
            headline="Article 1", pub_date=datetime(2005, 7, 26)
        )
        cls.a2 = Article.objects.create(
            headline="Article 2", pub_date=datetime(2005, 7, 27)
        )
        cls.a3 = Article.objects.create(
            headline="Article 3", pub_date=datetime(2005, 7, 27)
        )
        cls.a4 = Article.objects.create(
            headline="Article 4", pub_date=datetime(2005, 7, 28)
        )
        cls.author_1 = Author.objects.create(name="Name 1")
        cls.author_2 = Author.objects.create(name="Name 2")
        for i in range(2):
            Author.objects.create()

    def test_default_ordering(self):
        """
        By default, Article.objects.all() orders by pub_date descending, then
        headline ascending.
        """
        self.assertQuerySetEqual(
            Article.objects.all(),
            [
                "Article 4",
                "Article 2",
                "Article 3",
                "Article 1",
            ],
            attrgetter("headline"),
        )

        # Getting a single item should work too:
        self.assertEqual(Article.objects.all()[0], self.a4)

    def test_default_ordering_override(self):
        """
        Override ordering with order_by, which is in the same format as the
        ordering attribute in models.
        """
        self.assertQuerySetEqual(
            Article.objects.order_by("headline"),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            Article.objects.order_by("pub_date", "-headline"),
            [
                "Article 1",
                "Article 3",
                "Article 2",
                "Article 4",
            ],
            attrgetter("headline"),
        )

    def test_default_ordering_override_unknown_field(self):
        """
        Attempts to override default ordering on related models with an unknown
        field should result in an error.
        """
        msg = (
            "Cannot resolve keyword 'unknown_field' into field. Choices are: "
            "article, author, editor, editor_id, id, name"
        )
        with self.assertRaisesMessage(FieldError, msg):
            list(Article.objects.order_by("author__unknown_field"))

    def test_order_by_override(self):
        """
        Only the last order_by has any effect (since they each override any
        previous ordering).
        """
        self.assertQuerySetEqual(
            Article.objects.order_by("id"),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            Article.objects.order_by("id").order_by("-headline"),
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
            attrgetter("headline"),
        )

    def test_order_by_nulls_first_and_last(self):
        msg = "nulls_first and nulls_last are mutually exclusive"
        with self.assertRaisesMessage(ValueError, msg):
            Article.objects.order_by(
                F("author").desc(nulls_last=True, nulls_first=True)
            )

    def assertQuerySetEqualReversible(self, queryset, sequence):
        self.assertSequenceEqual(queryset, sequence)
        self.assertSequenceEqual(queryset.reverse(), list(reversed(sequence)))

    def test_order_by_nulls_last(self):
        Article.objects.filter(headline="Article 3").update(author=self.author_1)
        Article.objects.filter(headline="Article 4").update(author=self.author_2)
        # asc and desc are chainable with nulls_last.
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(F("author").desc(nulls_last=True), "headline"),
            [self.a4, self.a3, self.a1, self.a2],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(F("author").asc(nulls_last=True), "headline"),
            [self.a3, self.a4, self.a1, self.a2],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(
                Upper("author__name").desc(nulls_last=True), "headline"
            ),
            [self.a4, self.a3, self.a1, self.a2],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(
                Upper("author__name").asc(nulls_last=True), "headline"
            ),
            [self.a3, self.a4, self.a1, self.a2],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.annotate(upper_name=Upper("author__name")).order_by(
                F("upper_name").asc(nulls_last=True), "headline"
            ),
            [self.a3, self.a4, self.a1, self.a2],
        )

    def test_order_by_nulls_first(self):
        Article.objects.filter(headline="Article 3").update(author=self.author_1)
        Article.objects.filter(headline="Article 4").update(author=self.author_2)
        # asc and desc are chainable with nulls_first.
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(F("author").asc(nulls_first=True), "headline"),
            [self.a1, self.a2, self.a3, self.a4],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(F("author").desc(nulls_first=True), "headline"),
            [self.a1, self.a2, self.a4, self.a3],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(
                Upper("author__name").asc(nulls_first=True), "headline"
            ),
            [self.a1, self.a2, self.a3, self.a4],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.order_by(
                Upper("author__name").desc(nulls_first=True), "headline"
            ),
            [self.a1, self.a2, self.a4, self.a3],
        )
        self.assertQuerySetEqualReversible(
            Article.objects.annotate(upper_name=Upper("author__name")).order_by(
                F("upper_name").desc(nulls_first=True), "headline"
            ),
            [self.a1, self.a2, self.a4, self.a3],
        )

    def test_orders_nulls_first_on_filtered_subquery(self):
        Article.objects.filter(headline="Article 1").update(author=self.author_1)
        Article.objects.filter(headline="Article 2").update(author=self.author_1)
        Article.objects.filter(headline="Article 4").update(author=self.author_2)
        Author.objects.filter(name__isnull=True).delete()
        author_3 = Author.objects.create(name="Name 3")
        article_subquery = (
            Article.objects.filter(
                author=OuterRef("pk"),
                headline__icontains="Article",
            )
            .order_by()
            .values("author")
            .annotate(
                last_date=Max("pub_date"),
            )
            .values("last_date")
        )
        self.assertQuerySetEqualReversible(
            Author.objects.annotate(
                last_date=Subquery(article_subquery, output_field=DateTimeField())
            )
            .order_by(F("last_date").asc(nulls_first=True))
            .distinct(),
            [author_3, self.author_1, self.author_2],
        )

    def test_stop_slicing(self):
        """
        Use the 'stop' part of slicing notation to limit the results.
        """
        self.assertQuerySetEqual(
            Article.objects.order_by("headline")[:2],
            [
                "Article 1",
                "Article 2",
            ],
            attrgetter("headline"),
        )

    def test_stop_start_slicing(self):
        """
        Use the 'stop' and 'start' parts of slicing notation to offset the
        result list.
        """
        self.assertQuerySetEqual(
            Article.objects.order_by("headline")[1:3],
            [
                "Article 2",
                "Article 3",
            ],
            attrgetter("headline"),
        )

    def test_random_ordering(self):
        """
        Use '?' to order randomly.
        """
        self.assertEqual(len(list(Article.objects.order_by("?"))), 4)

    def test_reversed_ordering(self):
        """
        Ordering can be reversed using the reverse() method on a queryset.
        This allows you to extract things like "the last two items" (reverse
        and then take the first two).
        """
        self.assertQuerySetEqual(
            Article.objects.reverse()[:2],
            [
                "Article 1",
                "Article 3",
            ],
            attrgetter("headline"),
        )

    def test_reverse_ordering_pure(self):
        qs1 = Article.objects.order_by(F("headline").asc())
        qs2 = qs1.reverse()
        self.assertQuerySetEqual(
            qs2,
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            qs1,
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )

    def test_reverse_meta_ordering_pure(self):
        Article.objects.create(
            headline="Article 5",
            pub_date=datetime(2005, 7, 30),
            author=self.author_1,
            second_author=self.author_2,
        )
        Article.objects.create(
            headline="Article 5",
            pub_date=datetime(2005, 7, 30),
            author=self.author_2,
            second_author=self.author_1,
        )
        self.assertQuerySetEqual(
            Article.objects.filter(headline="Article 5").reverse(),
            ["Name 2", "Name 1"],
            attrgetter("author.name"),
        )
        self.assertQuerySetEqual(
            Article.objects.filter(headline="Article 5"),
            ["Name 1", "Name 2"],
            attrgetter("author.name"),
        )

    def test_no_reordering_after_slicing(self):
        msg = "Cannot reverse a query once a slice has been taken."
        qs = Article.objects.all()[0:2]
        with self.assertRaisesMessage(TypeError, msg):
            qs.reverse()
        with self.assertRaisesMessage(TypeError, msg):
            qs.last()

    def test_extra_ordering(self):
        """
        Ordering can be based on fields included from an 'extra' clause
        """
        self.assertQuerySetEqual(
            Article.objects.extra(
                select={"foo": "pub_date"}, order_by=["foo", "headline"]
            ),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )

    def test_extra_ordering_quoting(self):
        """
        If the extra clause uses an SQL keyword for a name, it will be
        protected by quoting.
        """
        self.assertQuerySetEqual(
            Article.objects.extra(
                select={"order": "pub_date"}, order_by=["order", "headline"]
            ),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )

    def test_extra_ordering_with_table_name(self):
        self.assertQuerySetEqual(
            Article.objects.extra(order_by=["ordering_article.headline"]),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            Article.objects.extra(order_by=["-ordering_article.headline"]),
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
            attrgetter("headline"),
        )

    def test_order_by_pk(self):
        """
        'pk' works as an ordering option in Meta.
        """
        self.assertEqual(
            [a.pk for a in Author.objects.all()],
            [a.pk for a in Author.objects.order_by("-pk")],
        )

    def test_order_by_fk_attname(self):
        """
        ordering by a foreign key by its attribute name prevents the query
        from inheriting its related model ordering option (#19195).
        """
        authors = list(Author.objects.order_by("id"))
        for i in range(1, 5):
            author = authors[i - 1]
            article = getattr(self, "a%d" % (5 - i))
            article.author = author
            article.save(update_fields={"author"})

        self.assertQuerySetEqual(
            Article.objects.order_by("author_id"),
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
            attrgetter("headline"),
        )

    def test_order_by_self_referential_fk(self):
        self.a1.author = Author.objects.create(editor=self.author_1)
        self.a1.save()
        self.a2.author = Author.objects.create(editor=self.author_2)
        self.a2.save()
        self.assertQuerySetEqual(
            Article.objects.filter(author__isnull=False).order_by("author__editor"),
            ["Article 2", "Article 1"],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            Article.objects.filter(author__isnull=False).order_by("author__editor_id"),
            ["Article 1", "Article 2"],
            attrgetter("headline"),
        )

    def test_order_by_f_expression(self):
        self.assertQuerySetEqual(
            Article.objects.order_by(F("headline")),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            Article.objects.order_by(F("headline").asc()),
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )
        self.assertQuerySetEqual(
            Article.objects.order_by(F("headline").desc()),
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
            attrgetter("headline"),
        )

    def test_order_by_f_expression_duplicates(self):
        """
        A column may only be included once (the first occurrence) so we check
        to ensure there are no duplicates by inspecting the SQL.
        """
        qs = Article.objects.order_by(F("headline").asc(), F("headline").desc())
        sql = str(qs.query).upper()
        fragment = sql[sql.find("ORDER BY") :]
        self.assertEqual(fragment.count("HEADLINE"), 1)
        self.assertQuerySetEqual(
            qs,
            [
                "Article 1",
                "Article 2",
                "Article 3",
                "Article 4",
            ],
            attrgetter("headline"),
        )
        qs = Article.objects.order_by(F("headline").desc(), F("headline").asc())
        sql = str(qs.query).upper()
        fragment = sql[sql.find("ORDER BY") :]
        self.assertEqual(fragment.count("HEADLINE"), 1)
        self.assertQuerySetEqual(
            qs,
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
            attrgetter("headline"),
        )

    def test_order_by_constant_value(self):
        # Order by annotated constant from selected columns.
        qs = Article.objects.annotate(
            constant=Value("1", output_field=CharField()),
        ).order_by("constant", "-headline")
        self.assertSequenceEqual(qs, [self.a4, self.a3, self.a2, self.a1])
        # Order by annotated constant which is out of selected columns.
        self.assertSequenceEqual(
            qs.values_list("headline", flat=True),
            [
                "Article 4",
                "Article 3",
                "Article 2",
                "Article 1",
            ],
        )
        # Order by constant.
        qs = Article.objects.order_by(Value("1", output_field=CharField()), "-headline")
        self.assertSequenceEqual(qs, [self.a4, self.a3, self.a2, self.a1])

    def test_order_by_case_when_constant_value(self):
        qs = Article.objects.order_by(
            Case(
                When(pk__in=[], then=Value(1)),
                default=Value(0),
                output_field=IntegerField(),
            ).desc(),
            "pk",
        )
        self.assertSequenceEqual(qs, [self.a1, self.a2, self.a3, self.a4])

    def test_related_ordering_duplicate_table_reference(self):
        """
        An ordering referencing a model with an ordering referencing a model
        multiple time no circular reference should be detected (#24654).
        """
        first_author = Author.objects.create()
        second_author = Author.objects.create()
        self.a1.author = first_author
        self.a1.second_author = second_author
        self.a1.save()
        self.a2.author = second_author
        self.a2.second_author = first_author
        self.a2.save()
        r1 = Reference.objects.create(article_id=self.a1.pk)
        r2 = Reference.objects.create(article_id=self.a2.pk)
        self.assertSequenceEqual(Reference.objects.all(), [r2, r1])

    def test_default_ordering_by_f_expression(self):
        """F expressions can be used in Meta.ordering."""
        articles = OrderedByFArticle.objects.all()
        articles.filter(headline="Article 2").update(author=self.author_2)
        articles.filter(headline="Article 3").update(author=self.author_1)
        self.assertQuerySetEqual(
            articles,
            ["Article 1", "Article 4", "Article 3", "Article 2"],
            attrgetter("headline"),
        )

    def test_order_by_ptr_field_with_default_ordering_by_expression(self):
        ca1 = ChildArticle.objects.create(
            headline="h2",
            pub_date=datetime(2005, 7, 27),
            author=self.author_2,
        )
        ca2 = ChildArticle.objects.create(
            headline="h2",
            pub_date=datetime(2005, 7, 27),
            author=self.author_1,
        )
        ca3 = ChildArticle.objects.create(
            headline="h3",
            pub_date=datetime(2005, 7, 27),
            author=self.author_1,
        )
        ca4 = ChildArticle.objects.create(headline="h1", pub_date=datetime(2005, 7, 28))
        articles = ChildArticle.objects.order_by("article_ptr")
        self.assertSequenceEqual(articles, [ca4, ca2, ca1, ca3])

    def test_default_ordering_does_not_affect_group_by(self):
        Article.objects.exclude(headline="Article 4").update(author=self.author_1)
        Article.objects.filter(headline="Article 4").update(author=self.author_2)
        articles = Article.objects.values("author").annotate(count=Count("author"))
        self.assertCountEqual(
            articles,
            [
                {"author": self.author_1.pk, "count": 3},
                {"author": self.author_2.pk, "count": 1},
            ],
        )

    def test_order_by_parent_fk_with_expression_in_default_ordering(self):
        p3 = OrderedByExpression.objects.create(name="oBJ 3")
        p2 = OrderedByExpression.objects.create(name="OBJ 2")
        p1 = OrderedByExpression.objects.create(name="obj 1")
        c3 = OrderedByExpressionChild.objects.create(parent=p3)
        c2 = OrderedByExpressionChild.objects.create(parent=p2)
        c1 = OrderedByExpressionChild.objects.create(parent=p1)
        self.assertSequenceEqual(
            OrderedByExpressionChild.objects.order_by("parent"),
            [c1, c2, c3],
        )

    def test_order_by_grandparent_fk_with_expression_in_default_ordering(self):
        p3 = OrderedByExpression.objects.create(name="oBJ 3")
        p2 = OrderedByExpression.objects.create(name="OBJ 2")
        p1 = OrderedByExpression.objects.create(name="obj 1")
        c3 = OrderedByExpressionChild.objects.create(parent=p3)
        c2 = OrderedByExpressionChild.objects.create(parent=p2)
        c1 = OrderedByExpressionChild.objects.create(parent=p1)
        g3 = OrderedByExpressionGrandChild.objects.create(parent=c3)
        g2 = OrderedByExpressionGrandChild.objects.create(parent=c2)
        g1 = OrderedByExpressionGrandChild.objects.create(parent=c1)
        self.assertSequenceEqual(
            OrderedByExpressionGrandChild.objects.order_by("parent"),
            [g1, g2, g3],
        )

    def test_order_by_expression_ref(self):
        self.assertQuerySetEqual(
            Author.objects.annotate(upper_name=Upper("name")).order_by(
                Length("upper_name")
            ),
            Author.objects.order_by(Length(Upper("name"))),
        )

    def test_ordering_select_related_collision(self):
        self.assertEqual(
            Article.objects.select_related("author")
            .annotate(name=Upper("author__name"))
            .filter(pk=self.a1.pk)
            .order_by(OrderBy(F("name")))
            .first(),
            self.a1,
        )
        self.assertEqual(
            Article.objects.select_related("author")
            .annotate(name=Upper("author__name"))
            .filter(pk=self.a1.pk)
            .order_by("name")
            .first(),
            self.a1,
        )

    def test_order_by_expr_query_reuse(self):
        qs = Author.objects.annotate(num=Count("article")).order_by(
            F("num").desc(), "pk"
        )
        self.assertCountEqual(qs, qs.iterator())
