import unittest

from django.db import connection
from django.test import TransactionTestCase, skipUnlessDBFeature

from ..models import Person, Square


@unittest.skipUnless(connection.vendor == "oracle", "Oracle tests")
class DatabaseSequenceTests(TransactionTestCase):
    available_apps = []

    def test_get_sequences(self):
        with connection.cursor() as cursor:
            seqs = connection.introspection.get_sequences(
                cursor, Square._meta.db_table, Square._meta.local_fields
            )
            self.assertEqual(len(seqs), 1)
            self.assertIsNotNone(seqs[0]["name"])
            self.assertEqual(seqs[0]["table"], Square._meta.db_table)
            self.assertEqual(seqs[0]["column"], "id")

    def test_get_sequences_manually_created_index(self):
        with connection.cursor() as cursor:
            with connection.schema_editor() as editor:
                editor._drop_identity(Square._meta.db_table, "id")
                seqs = connection.introspection.get_sequences(
                    cursor, Square._meta.db_table, Square._meta.local_fields
                )
                self.assertEqual(
                    seqs, [{"table": Square._meta.db_table, "column": "id"}]
                )
                # Recreate model, because adding identity is impossible.
                editor.delete_model(Square)
                editor.create_model(Square)

    @skipUnlessDBFeature("supports_collation_on_charfield")
    def test_get_table_description_view_default_collation(self):
        person_table = connection.introspection.identifier_converter(
            Person._meta.db_table
        )
        first_name_column = connection.ops.quote_name(
            Person._meta.get_field("first_name").column
        )
        person_view = connection.introspection.identifier_converter("TEST_PERSON_VIEW")
        with connection.cursor() as cursor:
            cursor.execute(
                f"CREATE VIEW {person_view} "
                f"AS SELECT {first_name_column} FROM {person_table}"
            )
            try:
                columns = connection.introspection.get_table_description(
                    cursor, person_view
                )
                self.assertEqual(len(columns), 1)
                self.assertIsNone(columns[0].collation)
            finally:
                cursor.execute(f"DROP VIEW {person_view}")

    @skipUnlessDBFeature("supports_collation_on_charfield")
    def test_get_table_description_materialized_view_non_default_collation(self):
        person_table = connection.introspection.identifier_converter(
            Person._meta.db_table
        )
        first_name_column = connection.ops.quote_name(
            Person._meta.get_field("first_name").column
        )
        person_mview = connection.introspection.identifier_converter(
            "TEST_PERSON_MVIEW"
        )
        collation = connection.features.test_collations.get("ci")
        with connection.cursor() as cursor:
            cursor.execute(
                f"CREATE MATERIALIZED VIEW {person_mview} "
                f"DEFAULT COLLATION {collation} "
                f"AS SELECT {first_name_column} FROM {person_table}"
            )
            try:
                columns = connection.introspection.get_table_description(
                    cursor, person_mview
                )
                self.assertEqual(len(columns), 1)
                self.assertIsNotNone(columns[0].collation)
                self.assertNotEqual(columns[0].collation, collation)
            finally:
                cursor.execute(f"DROP MATERIALIZED VIEW {person_mview}")