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

from datetime import date, timedelta

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 = date(2025, 6, 15)
        dob = today.replace(year=today.year - 18)
        assert calculate_age(dob, today=today) == 18

    def test_just_turned_18(self):
        """A person who turned 18 yesterday is 18."""
        today = date(2025, 6, 15)
        dob = today.replace(year=today.year - 18) - timedelta(days=1)
        assert calculate_age(dob, today=today) == 18

    def test_one_day_short_of_18(self):
        """A person born one day after their 18th birthday is 17."""
        today = date(2025, 6, 15)
        dob = today.replace(year=today.year - 18) + timedelta(days=1)
        assert calculate_age(dob, today=today) == 17

    def test_17_years_old(self):
        """A person who is 17 years old today is 17."""
        today = date(2025, 6, 15)
        dob = date(2008, 6, 15)
        assert calculate_age(dob, today=today) == 17

    def test_65_years_old(self):
        """A person who is 65 is correctly calculated."""
        today = date(2025, 6, 15)
        dob = today.replace(year=today.year - 65)
        assert calculate_age(dob, today=today) == 65

    def test_newborn(self):
        """A newborn is 0."""
        today = date(2025, 6, 15)
        dob = today
        assert calculate_age(dob, today=today) == 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)
        assert calculate_age(dob, today=date(2025, 1, 1)) == 24

    def test_birthday_today(self):
        """Person born Dec 31, 2000 — on Dec 31, 2024 they turn 24."""
        dob = date(2000, 12, 31)
        assert calculate_age(dob, today=date(2024, 12, 31)) == 24


class TestRegisterRequestDateValidation:
    """Tests for the RegisterRequest date_of_birth field validator."""

    @pytest.mark.parametrize(
        "dob",
        [
            "2000-01-01",
            "1990-12-31",
            "2004-02-29",  # leap day
        ],
    )
    def test_valid_dates(self, dob):
        """Valid YYYY-MM-DD dates pass validation."""
        from app.routers.auth import RegisterRequest

        req = RegisterRequest(username="u", email="u@example.com", password="p", date_of_birth=dob)
        assert req.date_of_birth == dob

    @pytest.mark.parametrize(
        "dob",
        [
            "01-01-2000",
            "2000/01/01",
            "2000-13-01",
            "2000-00-10",
            "not-a-date",
            "",
        ],
    )
    def test_invalid_dates_rejected(self, dob):
        """Invalid dates are rejected by the validator."""
        from app.routers.auth import RegisterRequest

        with pytest.raises(ValueError):
            RegisterRequest(username="u", email="u@example.com", password="p", date_of_birth=dob)