<?php

declare(strict_types = 1);

/**
 * This file is part of the 'Yasumi' package.
 *
 * The easy PHP Library for calculating holidays.
 *
 * Copyright (c) 2015 - 2026 AzuyaLabs
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 *
 * @author Sacha Telgenhof <me at sachatelgenhof dot com>
 */

namespace Yasumi\Provider;

use Yasumi\Exception\UnknownLocaleException;
use Yasumi\Holiday;
use Yasumi\SubstituteHoliday;

/**
 * Provider for all holidays in Ukraine.
 *
 * Class Ukraine
 *
 * @author  Dmitry Machin <machin.dmitry@gmail.com>
 */
class Ukraine extends AbstractProvider
{
    use CommonHolidays;
    use ChristianHolidays;

    /**
     * Code to identify this Holiday Provider.
     * Typically, this is the ISO3166 code corresponding to the respective country or sub-region.
     */
    public const ID = 'UA';

    /**
     * Initialize holidays for Ukraine.
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    public function initialize(): void
    {
        $this->timezone = 'Europe/Kiev';

        // Add common holidays
        // New Years Day will not be substituted to an monday if it's on a weekend!
        $this->addHoliday($this->newYearsDay($this->year, $this->timezone, $this->locale), false);
        $this->addHoliday($this->internationalWorkersDay($this->year, $this->timezone, $this->locale));
        $this->addHoliday($this->internationalWomensDay($this->year, $this->timezone, $this->locale));

        // Add Christian holidays
        $this->addHoliday($this->easter($this->year, $this->timezone, $this->locale));
        $this->addHoliday($this->pentecost($this->year, $this->timezone, $this->locale));

        // Add other holidays
        $this->calculateOrthodoxChristmasDay();
        $this->calculateSecondInternationalWorkersDay();
        $this->calculateVictoryDay();
        $this->calculateConstitutionDay();
        $this->calculateIndependenceDay();
        $this->calculateDefenderOfUkraineDay();
        $this->calculateCatholicChristmasDay();
    }

    public function getSources(): array
    {
        return [
            'https://en.wikipedia.org/wiki/Public_holidays_in_Ukraine',
            'https://uk.wikipedia.org/wiki/%D0%9D%D0%B5%D1%80%D0%BE%D0%B1%D0%BE%D1%87%D1%96_%D0%B4%D0%BD%D1%96_%D0%B2_%D0%A3%D0%BA%D1%80%D0%B0%D1%97%D0%BD%D1%96',
            'https://zakon.rada.gov.ua/laws/show/322-08',
        ];
    }

    /**
     * Adds a holiday to the holidays providers (i.e. country/state) list of holidays.
     *
     * @param Holiday $holiday       holiday instance (representing a holiday) to be added to the internal list
     *                               of holidays of this country
     * @param bool    $substitutable holidays on a weekend will be substituted to the next monday
     *
     * @throws UnknownLocaleException
     * @throws \InvalidArgumentException
     * @throws \Exception
     */
    public function addHoliday(Holiday $holiday, bool $substitutable = true): void
    {
        parent::addHoliday($holiday);

        if (! $substitutable) {
            return;
        }

        // Substitute holiday is on the next available weekday
        // if a holiday falls on a Saturday or Sunday.
        if ($this->isWeekendDay($holiday)) {
            $date = clone $holiday;
            $date->modify('next monday');

            parent::addHoliday(new SubstituteHoliday(
                $holiday,
                [],
                $date,
                $this->locale
            ));
        }
    }

    /**
     * @return \DateTime|\DateTimeImmutable
     *
     * @throws \Exception
     */
    protected function calculateEaster(int $year, string $timezone): \DateTimeInterface
    {
        return $this->calculateOrthodoxEaster($year, $timezone);
    }

    /**
     * Christmas Day.
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateOrthodoxChristmasDay(): void
    {
        if ($this->year >= 2024) {
            return;
        }

        $this->addHoliday(new Holiday(
            'christmasDay',
            [],
            new \DateTime("{$this->year}-01-07", new \DateTimeZone($this->timezone)),
            $this->locale
        ));
    }

    /**
     * International Workers' Day.
     * National holiday until 2018.
     *
     * @see https://en.wikipedia.org/wiki/International_Workers%27_Day#Ukraine
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateSecondInternationalWorkersDay(): void
    {
        if ($this->year >= 2018) {
            return;
        }

        $this->addHoliday(new Holiday('secondInternationalWorkersDay', [
            'uk' => 'День міжнародної солідарності трудящих',
            'ru' => 'День международной солидарности трудящихся',
        ], new \DateTime("{$this->year}-05-02", new \DateTimeZone($this->timezone)), $this->locale));
    }

    /**
     * Victory Day over Nazism in World War II.
     *
     * Victory Day over Nazism in World War II (Ukrainian: День перемоги над нацизмом у Другій світовій війні)
     * or Victory Day (Ukrainian: День перемоги) is a national holiday and a day off in Ukraine.
     * It was first celebrated on 9 May 2015 and follows the Day of Remembrance and Reconciliation on May 8.
     * The holiday replaced the Soviet "Victory Day", which was celebrated in the post-Soviet Union states, including
     * Ukraine, until 2014 inclusive. Since 2024, it has been celebrated on May 8.
     *
     * @see https://en.wikipedia.org/wiki/Victory_Day_over_Nazism_in_World_War_II
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateVictoryDay(): void
    {
        if ($this->year >= 2024) {
            $this->addHoliday(new Holiday(
                'victoryDay',
                ['uk' => 'День перемоги', 'ru' => 'День победы'],
                new \DateTime("{$this->year}-05-08", new \DateTimeZone($this->timezone)),
                $this->locale
            ));
        } elseif ($this->year >= 2015) {
            $this->addHoliday(new Holiday(
                'victoryDay',
                ['uk' => 'День перемоги', 'ru' => 'День победы'],
                new \DateTime("{$this->year}-05-09", new \DateTimeZone($this->timezone)),
                $this->locale
            ));
        }
    }

    /**
     * Constitution Day.
     *
     * Constitution Day (Ukrainian: День Конституції) is an Ukrainian public holiday celebrated on 28 June since 1996.
     *
     * @see https://en.wikipedia.org/wiki/Constitution_Day_(Ukraine)
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateConstitutionDay(): void
    {
        if ($this->year >= 2024) {
            $this->addHoliday(new Holiday(
                'constitutionDay',
                ['uk' => 'День Конституції', 'ru' => 'День Конституции'],
                new \DateTime("{$this->year}-06-15", new \DateTimeZone($this->timezone)),
                $this->locale
            ));
        } elseif ($this->year >= 1996) {
            $this->addHoliday(new Holiday(
                'constitutionDay',
                ['uk' => 'День Конституції', 'ru' => 'День Конституции'],
                new \DateTime("{$this->year}-06-28", new \DateTimeZone($this->timezone)),
                $this->locale
            ));
        }
    }

    /**
     * Independence Day.
     *
     * The Act of Declaration of Independence of Ukraine (Ukrainian: Акт проголошення незалежності України, translit.
     * Akt proholoshennya nezalezhnosti Ukrayiny) was adopted by the Ukrainian parliament on 24 August 1991.
     * The Act established Ukraine as an independent state.
     *
     * @see https://en.wikipedia.org/wiki/Declaration_of_Independence_of_Ukraine
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateIndependenceDay(): void
    {
        if ($this->year < 1991) {
            return;
        }

        $this->addHoliday(new Holiday(
            'independenceDay',
            ['uk' => 'День Незалежності', 'ru' => 'День Независимости'],
            new \DateTime("{$this->year}-08-24", new \DateTimeZone($this->timezone)),
            $this->locale
        ));
    }

    /**
     * Defender of Ukraine Day.
     *
     * Defender of Ukraine Day (Ukrainian: День захисника України, Denʹ zakhysnyka Ukrayiny)
     * is a state holiday in Ukraine celebrated annually on October 14.
     * Its first celebration was in 2015.
     * Starting from 2015, this day is considered a public holiday (this is thus a day off in Ukraine)
     *
     * @see https://en.wikipedia.org/wiki/Defender_of_Ukraine_Day
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateDefenderOfUkraineDay(): void
    {
        if ($this->year >= 2023) {
            $this->addHoliday(new Holiday(
                'defenderOfUkraineDay',
                ['uk' => 'День захисника України', 'ru' => 'День Защитника Украины'],
                new \DateTime("{$this->year}-10-01", new \DateTimeZone($this->timezone)),
                $this->locale
            ));
        } elseif ($this->year >= 2015) {
            $this->addHoliday(new Holiday(
                'defenderOfUkraineDay',
                ['uk' => 'День захисника України', 'ru' => 'День Защитника Украины'],
                new \DateTime("{$this->year}-10-14", new \DateTimeZone($this->timezone)),
                $this->locale
            ));
        }
    }

    /**
     * Catholic Christmas Day.
     * (since 2017 instead of International Workers' Day 2. May).
     *
     * @see https://en.wikipedia.org/wiki/Christmas_in_Ukraine
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateCatholicChristmasDay(): void
    {
        if ($this->year < 2017) {
            return;
        }

        $this->addHoliday(
            new Holiday(
                'catholicChristmasDay',
                [
                    'uk' => 'Католицький день Різдва',
                    'ru' => 'Католическое рождество',
                ],
                new \DateTime("{$this->year}-12-25", new \DateTimeZone($this->timezone)),
                $this->locale
            ),
            false  // Catholic Christmas Day will not be substituted to an monday if it's on a weekend!
        );
    }
}
