from django.db import connection

from django.db.models import F, Value

from django.db.models.functions import Collate

from django.test import TestCase

from ..models import Author

class CollateTests(TestCase):

    @classmethod

    def setUpTestData(cls):

        cls.author1 = Author.objects.create(alias="a", name="Jones 1")

        cls.author2 = Author.objects.create(alias="A", name="Jones 2")

    def test_collate_filter_ci(self):

        collation = connection.features.test_collations.get("ci")

        if not collation:

            self.skipTest("This backend does not support case-insensitive collations.")

        qs = Author.objects.filter(alias=Collate(Value("a"), collation))

        self.assertEqual(qs.count(), 2)

    def test_collate_order_by_cs(self):

        collation = connection.features.test_collations.get("cs")

        if not collation:

            self.skipTest("This backend does not support case-sensitive collations.")

        qs = Author.objects.order_by(Collate("alias", collation))

        self.assertSequenceEqual(qs, [self.author2, self.author1])

    def test_language_collation_order_by(self):

        collation = connection.features.test_collations.get("swedish_ci")

        if not collation:

            self.skipTest("This backend does not support language collations.")

        author3 = Author.objects.create(alias="O", name="Jones")

        author4 = Author.objects.create(alias="Ö", name="Jones")

        author5 = Author.objects.create(alias="P", name="Jones")

        qs = Author.objects.order_by(Collate(F("alias"), collation), "name")

        self.assertSequenceEqual(

            qs,

            [self.author1, self.author2, author3, author5, author4],

        )

    def test_invalid_collation(self):

        tests = [

            None,

            "",

            'et-x-icu" OR ',

            '"schema"."collation"',

        ]

        msg = "Invalid collation name: %r."

        for value in tests:

            with self.subTest(value), self.assertRaisesMessage(ValueError, msg % value):

                Collate(F("alias"), value)