import math

from decimal import Decimal

from django.db.models import DecimalField

from django.db.models.functions import ATan

from django.test import TestCase

from django.test.utils import register_lookup

from ..models import DecimalModel, FloatModel, IntegerModel

class ATanTests(TestCase):

    def test_null(self):

        IntegerModel.objects.create()

        obj = IntegerModel.objects.annotate(null_atan=ATan("normal")).first()

        self.assertIsNone(obj.null_atan)

    def test_decimal(self):

        DecimalModel.objects.create(n1=Decimal("-12.9"), n2=Decimal("0.6"))

        obj = DecimalModel.objects.annotate(

            n1_atan=ATan("n1"), n2_atan=ATan("n2")

        ).first()

        self.assertIsInstance(obj.n1_atan, Decimal)

        self.assertIsInstance(obj.n2_atan, Decimal)

        self.assertAlmostEqual(obj.n1_atan, Decimal(math.atan(obj.n1)))

        self.assertAlmostEqual(obj.n2_atan, Decimal(math.atan(obj.n2)))

    def test_float(self):

        FloatModel.objects.create(f1=-27.5, f2=0.33)

        obj = FloatModel.objects.annotate(

            f1_atan=ATan("f1"), f2_atan=ATan("f2")

        ).first()

        self.assertIsInstance(obj.f1_atan, float)

        self.assertIsInstance(obj.f2_atan, float)

        self.assertAlmostEqual(obj.f1_atan, math.atan(obj.f1))

        self.assertAlmostEqual(obj.f2_atan, math.atan(obj.f2))

    def test_integer(self):

        IntegerModel.objects.create(small=-20, normal=15, big=-1)

        obj = IntegerModel.objects.annotate(

            small_atan=ATan("small"),

            normal_atan=ATan("normal"),

            big_atan=ATan("big"),

        ).first()

        self.assertIsInstance(obj.small_atan, float)

        self.assertIsInstance(obj.normal_atan, float)

        self.assertIsInstance(obj.big_atan, float)

        self.assertAlmostEqual(obj.small_atan, math.atan(obj.small))

        self.assertAlmostEqual(obj.normal_atan, math.atan(obj.normal))

        self.assertAlmostEqual(obj.big_atan, math.atan(obj.big))

    def test_transform(self):

        with register_lookup(DecimalField, ATan):

            DecimalModel.objects.create(n1=Decimal("3.12"), n2=Decimal("0"))

            DecimalModel.objects.create(n1=Decimal("-5"), n2=Decimal("0"))

            obj = DecimalModel.objects.filter(n1__atan__gt=0).get()

            self.assertEqual(obj.n1, Decimal("3.12"))