<?php

use PHPUnit\Framework\Attributes\DataProvider;

final class CalendarTest extends LegacyTestCase
{
    #[DataProvider('leapYears')]
    public function testGregorianLeapYears(int $year, bool $expected): void
    {
        self::assertSame($expected, leapYear($year));
    }

    public static function leapYears(): array
    {
        return ['ordinary' => [2026, false], 'leap' => [2024, true],
            'century exception' => [1900, false], '400 years' => [2000, true],
            'future century' => [2100, false]];
    }

    #[DataProvider('monthLengths')]
    public function testMonthLength(int $year, int $month, int $expected): void
    {
        self::assertSame($expected, daysPerMonth($year, $month));
    }

    public static function monthLengths(): array
    {
        return [[2026, 1, 31], [2026, 2, 28], [2024, 2, 29], [1900, 2, 28],
            [2000, 2, 29], [2026, 4, 30], [2026, 12, 31]];
    }

    #[DataProvider('dayOffsets')]
    public function testDayArithmeticProducesValidCalendarDates(array $date, int $offset, array $expected): void
    {
        $actual = addDaysComplete(...[...$date, $offset]);
        self::assertSame($expected, $actual);
        self::assertTrue(checkdate($actual[1], $actual[2], $actual[0]));
    }

    public static function dayOffsets(): array
    {
        return [
            'unchanged' => [[2026, 10, 26], 0, [2026, 10, 26]],
            'next day' => [[2026, 10, 26], 1, [2026, 10, 27]],
            'year rollover' => [[2026, 12, 31], 1, [2027, 1, 1]],
            'February non-leap' => [[2026, 2, 28], 1, [2026, 3, 1]],
            'February leap' => [[2024, 2, 28], 1, [2024, 2, 29]],
            'leap rollover' => [[2024, 2, 29], 1, [2024, 3, 1]],
            'multiple months' => [[2026, 1, 31], 60, [2026, 4, 1]],
            'previous day same month' => [[2026, 10, 26], -1, [2026, 10, 25]],
            'previous year' => [[2026, 1, 1], -1, [2025, 12, 31]],
            'backwards into February' => [[2026, 3, 1], -1, [2026, 2, 28]],
            'backwards into leap February' => [[2024, 3, 1], -1, [2024, 2, 29]],
            'backwards into 30-day month' => [[2026, 5, 1], -1, [2026, 4, 30]],
            'backwards from short month' => [[2026, 4, 1], -1, [2026, 3, 31]],
        ];
    }

    #[DataProvider('monthOffsets')]
    public function testMonthArithmetic(int $year, int $month, int $offset, array $expected): void
    {
        self::assertSame($expected, addMonths($year, $month, $offset));
    }

    public static function monthOffsets(): array
    {
        return [[2026, 1, 0, [2026, 1]], [2026, 12, 1, [2027, 1]],
            [2026, 1, -1, [2025, 12]], [2026, 1, 25, [2028, 2]],
            [2026, 1, -13, [2024, 12]]];
    }
}