from datetime import datetime

from django.core.exceptions import FieldError
from django.db.models import BooleanField, CharField, F, Q
from django.db.models.expressions import Col, Func
from django.db.models.fields.related_lookups import RelatedIsNull
from django.db.models.functions import Lower
from django.db.models.lookups import Exact, GreaterThan, IsNull, LessThan
from django.db.models.sql.query import Query
from django.db.models.sql.where import OR
from django.test import SimpleTestCase
from django.test.utils import register_lookup

from .models import Author, Item, ObjectC, Ranking


class TestQuery(SimpleTestCase):
    def test_simple_query(self):
        query = Query(Author)
        where = query.build_where(Q(num__gt=2))
        lookup = where.children[0]
        self.assertIsInstance(lookup, GreaterThan)
        self.assertEqual(lookup.rhs, 2)
        self.assertEqual(lookup.lhs.target, Author._meta.get_field("num"))

    def test_non_alias_cols_query(self):
        query = Query(Author, alias_cols=False)
        where = query.build_where(Q(num__gt=2, name__isnull=False) | Q(num__lt=F("id")))

        name_isnull_lookup, num_gt_lookup = where.children[0].children
        self.assertIsInstance(num_gt_lookup, GreaterThan)
        self.assertIsInstance(num_gt_lookup.lhs, Col)
        self.assertIsNone(num_gt_lookup.lhs.alias)
        self.assertIsInstance(name_isnull_lookup, IsNull)
        self.assertIsInstance(name_isnull_lookup.lhs, Col)
        self.assertIsNone(name_isnull_lookup.lhs.alias)

        num_lt_lookup = where.children[1]
        self.assertIsInstance(num_lt_lookup, LessThan)
        self.assertIsInstance(num_lt_lookup.rhs, Col)
        self.assertIsNone(num_lt_lookup.rhs.alias)
        self.assertIsInstance(num_lt_lookup.lhs, Col)
        self.assertIsNone(num_lt_lookup.lhs.alias)

    def test_complex_query(self):
        query = Query(Author)
        where = query.build_where(Q(num__gt=2) | Q(num__lt=0))
        self.assertEqual(where.connector, OR)

        lookup = where.children[0]
        self.assertIsInstance(lookup, GreaterThan)
        self.assertEqual(lookup.rhs, 2)
        self.assertEqual(lookup.lhs.target, Author._meta.get_field("num"))

        lookup = where.children[1]
        self.assertIsInstance(lookup, LessThan)
        self.assertEqual(lookup.rhs, 0)
        self.assertEqual(lookup.lhs.target, Author._meta.get_field("num"))

    def test_multiple_fields(self):
        query = Query(Item, alias_cols=False)
        where = query.build_where(Q(modified__gt=F("created")))
        lookup = where.children[0]
        self.assertIsInstance(lookup, GreaterThan)
        self.assertIsInstance(lookup.rhs, Col)
        self.assertIsNone(lookup.rhs.alias)
        self.assertIsInstance(lookup.lhs, Col)
        self.assertIsNone(lookup.lhs.alias)
        self.assertEqual(lookup.rhs.target, Item._meta.get_field("created"))
        self.assertEqual(lookup.lhs.target, Item._meta.get_field("modified"))

    def test_transform(self):
        query = Query(Author, alias_cols=False)
        with register_lookup(CharField, Lower):
            where = query.build_where(~Q(name__lower="foo"))
        lookup = where.children[0]
        self.assertIsInstance(lookup, Exact)
        self.assertIsInstance(lookup.lhs, Lower)
        self.assertIsInstance(lookup.lhs.lhs, Col)
        self.assertIsNone(lookup.lhs.lhs.alias)
        self.assertEqual(lookup.lhs.lhs.target, Author._meta.get_field("name"))

    def test_negated_nullable(self):
        query = Query(Item)
        where = query.build_where(~Q(modified__lt=datetime(2017, 1, 1)))
        self.assertTrue(where.negated)
        lookup = where.children[0]
        self.assertIsInstance(lookup, LessThan)
        self.assertEqual(lookup.lhs.target, Item._meta.get_field("modified"))
        lookup = where.children[1]
        self.assertIsInstance(lookup, IsNull)
        self.assertEqual(lookup.lhs.target, Item._meta.get_field("modified"))

    def test_foreign_key(self):
        query = Query(Item)
        msg = "Joined field references are not permitted in this query"
        with self.assertRaisesMessage(FieldError, msg):
            query.build_where(Q(creator__num__gt=2))

    def test_foreign_key_f(self):
        query = Query(Ranking)
        with self.assertRaises(FieldError):
            query.build_where(Q(rank__gt=F("author__num")))

    def test_foreign_key_exclusive(self):
        query = Query(ObjectC, alias_cols=False)
        where = query.build_where(Q(objecta=None) | Q(objectb=None))
        a_isnull = where.children[0]
        self.assertIsInstance(a_isnull, RelatedIsNull)
        self.assertIsInstance(a_isnull.lhs, Col)
        self.assertIsNone(a_isnull.lhs.alias)
        self.assertEqual(a_isnull.lhs.target, ObjectC._meta.get_field("objecta"))
        b_isnull = where.children[1]
        self.assertIsInstance(b_isnull, RelatedIsNull)
        self.assertIsInstance(b_isnull.lhs, Col)
        self.assertIsNone(b_isnull.lhs.alias)
        self.assertEqual(b_isnull.lhs.target, ObjectC._meta.get_field("objectb"))

    def test_clone_select_related(self):
        query = Query(Item)
        query.add_select_related(["creator"])
        clone = query.clone()
        clone.add_select_related(["note", "creator__extra"])
        self.assertEqual(query.select_related, {"creator": {}})

    def test_iterable_lookup_value(self):
        query = Query(Item)
        where = query.build_where(Q(name=["a", "b"]))
        name_exact = where.children[0]
        self.assertIsInstance(name_exact, Exact)
        self.assertEqual(name_exact.rhs, "['a', 'b']")

    def test_filter_conditional(self):
        query = Query(Item)
        where = query.build_where(Func(output_field=BooleanField()))
        exact = where.children[0]
        self.assertIsInstance(exact, Exact)
        self.assertIsInstance(exact.lhs, Func)
        self.assertIs(exact.rhs, True)

    def test_filter_conditional_join(self):
        query = Query(Item)
        filter_expr = Func("note__note", output_field=BooleanField())
        msg = "Joined field references are not permitted in this query"
        with self.assertRaisesMessage(FieldError, msg):
            query.build_where(filter_expr)

    def test_filter_non_conditional(self):
        query = Query(Item)
        msg = "Cannot filter against a non-conditional expression."
        with self.assertRaisesMessage(TypeError, msg):
            query.build_where(Func(output_field=CharField()))