from django.test import TestCase

from labs.billing.exam import redeem_exam_with_credits
from labs.billing.exceptions import InsufficientCreditsError
from labs.billing.user import INITIAL_FREE_CREDITS_AMOUNT
from labs.models import (
    User,
    Exam,
    UserExamRedemption,
    CreditTransaction,
)


class TestBillingExam(TestCase):
    def setUp(self):
        self.user = User.objects.create_user(email="test@test.com")

    def test_redeem_exam_with_credits_success(self):
        exam = Exam.objects.create(code="exam_001", credits=1)

        redemption = redeem_exam_with_credits(user=self.user, exam=exam)
        self.assertEqual(redemption.user_id, self.user.id)
        self.assertEqual(redemption.exam_id, exam.id)
        self.assertIsNone(redemption.exam_attempt_id)
        self.assertEqual(redemption.redeem_type, UserExamRedemption.RedeemType.CREDITS)
        self.assertEqual(redemption.redeem_detail, {"credits": 1})

        self.user.credit_summary.refresh_from_db()
        self.assertEqual(
            self.user.credit_summary.free_credits,
            INITIAL_FREE_CREDITS_AMOUNT - 1,
        )
        self.assertEqual(self.user.credit_summary.paid_credits, 0)

        txn = CreditTransaction.objects.get(
            user=self.user,
            transaction_type=CreditTransaction.TransactionType.REDEEM_EXAM,
        )
        self.assertEqual(txn.paid_credits, 0)
        self.assertEqual(txn.free_credits, -1)
        self.assertIsNone(txn.redemption_id)
        self.assertEqual(txn.exam_redemption_id, redemption.id)

    def test_redeem_exam_with_credits_insufficient_credits(self):
        exam = Exam.objects.create(code="exam_001", credits=INITIAL_FREE_CREDITS_AMOUNT + 1)

        with self.assertRaises(InsufficientCreditsError):
            redeem_exam_with_credits(user=self.user, exam=exam)

        self.user.credit_summary.refresh_from_db()
        self.assertEqual(self.user.credit_summary.free_credits, INITIAL_FREE_CREDITS_AMOUNT)
        self.assertEqual(self.user.credit_summary.paid_credits, 0)
        self.assertEqual(UserExamRedemption.objects.filter(user=self.user).count(), 0)
        self.assertEqual(
            CreditTransaction.objects.filter(
                user=self.user,
                transaction_type=CreditTransaction.TransactionType.REDEEM_EXAM,
            ).count(),
            0,
        )

    def test_redeem_exam_with_credits_idempotent(self):
        exam = Exam.objects.create(code="exam_001", credits=1)

        redemption_1 = redeem_exam_with_credits(user=self.user, exam=exam)
        redemption_2 = redeem_exam_with_credits(user=self.user, exam=exam)
        self.assertEqual(redemption_1.id, redemption_2.id)

        self.assertEqual(
            UserExamRedemption.objects.filter(
                user=self.user, exam=exam, exam_attempt__isnull=True
            ).count(),
            1,
        )
        self.assertEqual(
            CreditTransaction.objects.filter(
                user=self.user,
                transaction_type=CreditTransaction.TransactionType.REDEEM_EXAM,
            ).count(),
            1,
        )

        self.user.credit_summary.refresh_from_db()
        self.assertEqual(
            self.user.credit_summary.free_credits,
            INITIAL_FREE_CREDITS_AMOUNT - 1,
        )
        self.assertEqual(self.user.credit_summary.paid_credits, 0)