"""Tests for the 18+ age gate on user registration."""

from datetime import date, timedelta, datetime
from unittest.mock import patch

import pytest

from app.routers.auth import calculate_age


class TestCalculateAge:
    """Unit tests for the calculate_age helper."""

    def test_exactly_18(self):
        """A person born exactly 18 years ago today is 18."""
        today = datetime.now().date()
        dob = today.replace(year=today.year - 18)
        assert calculate_age(dob) == 18

    def test_just_turned_18(self):
        """A person who turned 18 yesterday is 18."""
        today = datetime.now().date()
        dob = today.replace(year=today.year - 18) - timedelta(days=1)
        assert calculate_age(dob) == 18

    def test_one_day_short_of_18(self):
        """A person born one day after their 18th birthday is 17."""
        today = datetime.now().date()
        dob = today.replace(year=today.year - 18) + timedelta(days=1)
        assert calculate_age(dob) == 17

    def test_17_years_old(self):
        """A person who is 17 years and 364 days old is 17."""
        today = datetime.now().date()
        dob = today.replace(year=today.year - 17) + timedelta(days=1)
        assert calculate_age(dob) == 17

    def test_65_years_old(self):
        """A person who is 65 is correctly calculated."""
        today = datetime.now().date()
        dob = today.replace(year=today.year - 65)
        assert calculate_age(dob) == 65

    def test_newborn(self):
        """A newborn is 0."""
        today = datetime.now().date()
        dob = today
        assert calculate_age(dob) == 0

    def test_birthday_not_yet_this_year(self):
        """Person born Dec 31, 2000 — on Jan 1, 2025 they are still 24."""
        dob = date(2000, 12, 31)
        with patch("app.routers.auth.datetime") as mock_dt:
            mock_dt.now.return_value = datetime(2025, 1, 1)
            mock_dt.now.return_value.date.return_value = date(2025, 1, 1)
            assert calculate_age(dob) == 24

    def test_birthday_today(self):
        """Person born Dec 31, 2000 — on Dec 31, 2024 they turn 24."""
        dob = date(2000, 12, 31)
        with patch("app.routers.auth.datetime") as mock_dt:
            mock_dt.now.return_value = datetime(2024, 12, 31)
            mock_dt.now.return_value.date.return_value = date(2024, 12, 31)
            assert calculate_age(dob) == 24