from decimal import Decimal

from django.db.backends.signals import connection_created
from django.db.migrations.writer import MigrationWriter
from django.test.utils import modify_settings

from . import PostgreSQLTestCase

try:
    from psycopg2.extras import (
        DateRange, DateTimeRange, DateTimeTZRange, NumericRange,
    )

    from django.contrib.postgres.fields import (
        DateRangeField, DateTimeRangeField, DecimalRangeField,
        IntegerRangeField,
    )
except ImportError:
    pass


class PostgresConfigTests(PostgreSQLTestCase):
    def test_register_type_handlers_connection(self):
        from django.contrib.postgres.signals import register_type_handlers
        self.assertNotIn(register_type_handlers, connection_created._live_receivers(None))
        with modify_settings(INSTALLED_APPS={'append': 'django.contrib.postgres'}):
            self.assertIn(register_type_handlers, connection_created._live_receivers(None))
        self.assertNotIn(register_type_handlers, connection_created._live_receivers(None))

    def test_register_serializer_for_migrations(self):
        tests = (
            (DateRange(empty=True), DateRangeField),
            (DateTimeRange(empty=True), DateRangeField),
            (DateTimeTZRange(None, None, '[]'), DateTimeRangeField),
            (NumericRange(Decimal('1.0'), Decimal('5.0'), '()'), DecimalRangeField),
            (NumericRange(1, 10), IntegerRangeField),
        )

        def assertNotSerializable():
            for default, test_field in tests:
                with self.subTest(default=default):
                    field = test_field(default=default)
                    with self.assertRaisesMessage(ValueError, 'Cannot serialize: %s' % default.__class__.__name__):
                        MigrationWriter.serialize(field)

        assertNotSerializable()
        with self.modify_settings(INSTALLED_APPS={'append': 'django.contrib.postgres'}):
            for default, test_field in tests:
                with self.subTest(default=default):
                    field = test_field(default=default)
                    serialized_field, imports = MigrationWriter.serialize(field)
                    self.assertEqual(imports, {
                        'import django.contrib.postgres.fields.ranges',
                        'import psycopg2.extras',
                    })
                    self.assertIn(
                        '%s.%s(default=psycopg2.extras.%r)' % (
                            field.__module__,
                            field.__class__.__name__,
                            default,
                        ),
                        serialized_field
                    )
        assertNotSerializable()