<?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 the United Kingdom. Local holidays/observances (e.g. Wales, England, Guernsey, etc.)
 * are not part of this provider.
 */
class UnitedKingdom 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 = 'GB';

    public string $timezone = 'Europe/London';

    /**
     * Initialize holidays for the United Kingdom.
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    public function initialize(): void
    {
        // Add common holidays
        $this->calculateNewYearsDay();
        $this->calculateMayDayBankHoliday();
        $this->calculateSpringBankHoliday();
        $this->calculateSummerBankHoliday();

        // Add common Christian holidays (common in the United Kingdom)
        $this->addHoliday($this->goodFriday($this->year, $this->timezone, $this->locale));
        $this->calculateChristmasHolidays();

        // Add any other holidays
        $this->calculatePlatinumJubileeBankHoliday();
        $this->calculateMotheringSunday();
        $this->calculateQueenElizabethFuneralBankHoliday();
        $this->calculateKingCharlesCoronationBankHoliday();
    }

    public function getSources(): array
    {
        return [
            'https://en.wikipedia.org/wiki/Public_holidays_in_the_United_Kingdom',
        ];
    }

    /**
     * The first Monday of May is a bank holiday in the United Kingdom. It is called May Day in England, Wales and
     * Northern Ireland. It is known as the Early May Bank Holiday in Scotland. It probably originated as a Roman
     * festival honoring the beginning of the summer season (in the northern hemisphere). In more recent times, it has
     * been as a day to campaign for and celebrate workers' rights.
     *
     * The first Monday in May is a bank holiday and many people have a day off work. Many organizations, businesses
     * and schools are closed, while stores may be open or closed, according to local custom. Public transport systems
     * often run to a holiday timetable.
     *
     * @see https://www.timeanddate.com/holidays/uk/early-may-bank-holiday
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateMayDayBankHoliday(): void
    {
        // From 1978, by Royal Proclamation annually
        if ($this->year < 1978) {
            return;
        }

        // Moved to 8 May to commemorate the 50th (1995) and 75th (2020) anniversary of VE Day.
        if (1995 === $this->year || 2020 === $this->year) {
            $this->addHoliday(new Holiday(
                'mayDayBankHoliday',
                ['en' => 'May Day Bank Holiday'],
                new \DateTime("{$this->year}-5-8", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
                $this->locale,
                Holiday::TYPE_BANK
            ));

            return;
        }

        $this->addHoliday(new Holiday(
            'mayDayBankHoliday',
            ['en' => 'May Day Bank Holiday'],
            new \DateTime("first monday of may {$this->year}", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
            $this->locale,
            Holiday::TYPE_BANK
        ));
    }

    /**
     * The spring bank holiday, also known as the late May bank holiday, is a time for people in the United Kingdom to
     * have a day off work or school. It falls on the last Monday of May but it used to be on the Monday after
     * Pentecost.
     *
     * The last Monday in May is a bank holiday. Many organizations, businesses and schools are closed. Stores may be
     * open or closed, according to local custom. Public transport systems often run to a holiday timetable.
     *
     * @see https://www.timeanddate.com/holidays/uk/spring-bank-holiday
     * @see https://en.wikipedia.org/wiki/Public_holidays_in_the_United_Kingdom
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateSpringBankHoliday(): void
    {
        // Statutory bank holiday from 1971, following a trial period from 1965 to 1970.
        if ($this->year < 1965) {
            return;
        }

        // Moved to 4 June for the celebration of the Golden (2002) and Diamond (2012) Jubilee
        // of Elizabeth II.
        if (2002 === $this->year || 2012 === $this->year) {
            $this->addHoliday(new Holiday(
                'springBankHoliday',
                ['en' => 'Spring Bank Holiday'],
                new \DateTime("{$this->year}-6-4", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
                $this->locale,
                Holiday::TYPE_BANK
            ));

            return;
        }

        // Moved to 2 June in 2022 for the celebration of the Platinum Jubilee of Elizabeth II.
        if (2022 === $this->year) {
            $this->addHoliday(new Holiday(
                'springBankHoliday',
                ['en' => 'Spring Bank Holiday'],
                new \DateTime("{$this->year}-6-2", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
                $this->locale,
                Holiday::TYPE_BANK
            ));

            return;
        }

        $this->addHoliday(new Holiday(
            'springBankHoliday',
            ['en' => 'Spring Bank Holiday'],
            new \DateTime("last monday of may {$this->year}", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
            $this->locale,
            Holiday::TYPE_BANK
        ));
    }

    /**
     * The Platinum Jubilee bank holiday is an extra bank holiday added on 3 June 2022
     * for the celebration of the Platinum Jubilee of Elizabeth II.
     *
     * @see https://www.timeanddate.com/holidays/uk/queen-platinum-jubilee
     * @see https://en.wikipedia.org/wiki/Public_holidays_in_the_United_Kingdom#Special_holidays
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculatePlatinumJubileeBankHoliday(): void
    {
        if (2022 !== $this->year) {
            return;
        }

        $this->addHoliday(new Holiday(
            'platinumJubileeBankHoliday',
            ['en' => 'Platinum Jubilee Bank Holiday'],
            new \DateTime("{$this->year}-6-3", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
            $this->locale,
            Holiday::TYPE_BANK
        ));
    }

    /**
     * Queen Elizabeth II’s funeral is an extra bank holiday added on 10 September 2022
     * to mark the last day of the period of national mourning.
     *
     * @see https://www.timeanddate.com/holidays/uk/queen-elizabeth-funeral
     * @see https://www.gov.uk/government/news/bank-holiday-announced-for-her-majesty-queen-elizabeth-iis-state-funeral-on-monday-19-september
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateQueenElizabethFuneralBankHoliday(): void
    {
        if (2022 !== $this->year) {
            return;
        }

        $this->addHoliday(new Holiday(
            'queenElizabethFuneralBankHoliday',
            ['en' => 'Queen Elizabeth II’s State Funeral Bank Holiday'],
            new \DateTime("{$this->year}-9-19", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
            $this->locale,
            Holiday::TYPE_BANK
        ));
    }

    /**
     * The coronation of King Charles III is an extra bank holiday added on 6 November 2022
     * to mark the Coronation of His Majesty King Charles III.
     *
     * @see https://www.timeanddate.com/holidays/uk/king-coronation-day-holiday
     * @see https://www.gov.uk/government/news/bank-holiday-proclaimed-in-honour-of-the-coronation-of-his-majesty-king-charles-iii
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateKingCharlesCoronationBankHoliday(): void
    {
        if (2023 !== $this->year) {
            return;
        }

        $this->addHoliday(new Holiday(
            'kingCharlesCoronationBankHoliday',
            ['en' => 'King Charles III’s Coronation Bank Holiday'],
            new \DateTime("{$this->year}-5-8", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
            $this->locale,
            Holiday::TYPE_BANK
        ));
    }

    /**
     * Christmas Day is celebrated in the United Kingdom on December 25. It traditionally celebrates Jesus Christ's
     * birth but many aspects of this holiday have pagan origins. Christmas is a time for many people to give and
     * receive gifts and prepare special festive meals.
     *
     * Boxing Day in the United Kingdom is the day after Christmas Day and falls on December 26. Traditionally, it was
     * a
     * day when employers distributed money, food, cloth (material) or other valuable goods to their employees.
     * In modern times, it is an important day for sporting events and the start of the post-Christmas sales.
     *
     * Boxing Day is a bank holiday. If Boxing Day falls on a Saturday, the following Monday is a bank holiday.
     * If Christmas Day falls on a Saturday, the following Monday and Tuesday are bank holidays. All schools and many
     * organizations are closed in this period. Some may close for the whole week between Christmas and New Year.
     *
     * @see https://www.timeanddate.com/holidays/uk/christmas-day
     * @see https://www.timeanddate.com/holidays/uk/boxing-day
     *
     * @param string|null $type the Holiday Type (e.g. Official, Seasonal, etc.)
     *
     * @throws \Exception
     */
    protected function calculateChristmasHolidays(?string $type = null): void
    {
        $christmasDay = $this->christmasDay($this->year, $this->timezone, $this->locale, $type ?? Holiday::TYPE_OFFICIAL);
        $secondChristmasDay = $this->secondChristmasDay($this->year, $this->timezone, $this->locale, Holiday::TYPE_BANK);

        $this->addHoliday($christmasDay);
        $this->addHoliday($secondChristmasDay);

        if (\in_array((int) $christmasDay->format('w'), [0, 6], true)) {
            $date = clone $christmasDay;
            $date->add(new \DateInterval('P2D'));
            $this->addHoliday(new SubstituteHoliday(
                $christmasDay,
                [],
                $date,
                $this->locale,
                Holiday::TYPE_BANK
            ));
        }

        if (\in_array((int) $secondChristmasDay->format('w'), [0, 6], true)) {
            $date = clone $secondChristmasDay;
            $date->add(new \DateInterval('P2D'));
            $this->addHoliday(new SubstituteHoliday(
                $secondChristmasDay,
                [],
                $date,
                $this->locale,
                Holiday::TYPE_BANK
            ));
        }
    }

    /**
     * New Year's Day is a public holiday in the United Kingdom on January 1 each year. It marks
     * the start of the New Year in the Gregorian calendar. For many people have a quiet day on
     * January 1, which marks the end of the Christmas break before they return to work.
     *
     * If New Years Day falls on a Saturday or Sunday, it is observed the next Monday (January 2nd or 3rd)
     * Before 1871 it was not an observed or statutory holiday, after 1871 only an observed holiday.
     * Since 1974 (by Royal Proclamation) it was established as a bank holiday.
     *
     * @see https://en.wikipedia.org/wiki/Public_holidays_in_the_United_Kingdom
     * @see https://www.timeanddate.com/holidays/uk/new-year-day
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateNewYearsDay(): void
    {
        // Before 1871 it was not an observed or statutory holiday
        if ($this->year < 1871) {
            return;
        }

        $type = Holiday::TYPE_BANK;
        if ($this->year <= 1974) {
            $type = Holiday::TYPE_OBSERVANCE;
        }

        $newYearsDay = new \DateTime("{$this->year}-01-01", DateTimeZoneFactory::getDateTimeZone($this->timezone));

        // If New Years Day falls on a Saturday or Sunday, it is observed the next Monday (January 2nd or 3rd)
        if (\in_array((int) $newYearsDay->format('w'), [0, 6], true)) {
            $newYearsDay->modify('next monday');
        }

        $this->addHoliday(new Holiday('newYearsDay', [], $newYearsDay, $this->locale, $type));
    }

    /**
     * The Summer Bank holiday, also known as the Late Summer bank holiday, is a time for people in the United Kingdom
     * to have a day off work or school. It falls on the last Monday of August replacing the first Monday in August
     * (formerly commonly known as "August Bank Holiday").
     *
     * Many organizations, businesses and schools are closed. Stores may be open or closed, according to local custom.
     * Public transport systems often run to a holiday timetable.
     *
     * @see https://www.timeanddate.com/holidays/uk/summer-bank-holiday
     * @see https://en.wikipedia.org/wiki/Public_holidays_in_the_United_Kingdom
     *
     * @throws \InvalidArgumentException
     * @throws UnknownLocaleException
     * @throws \Exception
     */
    protected function calculateSummerBankHoliday(): void
    {
        if ($this->year < 1871) {
            return;
        }

        if ($this->year < 1965) {
            $this->addHoliday(new Holiday(
                'summerBankHoliday',
                ['en' => 'August Bank Holiday'],
                new \DateTime("first monday of august {$this->year}", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
                $this->locale,
                Holiday::TYPE_BANK
            ));

            return;
        }

        // Statutory bank holiday from 1971, following a trial period from 1965 to 1970.
        // During the trial period, the definition was different than today, causing exceptions
        // in 1968 and 1969.
        if (1968 === $this->year || 1969 === $this->year) {
            $this->addHoliday(new Holiday(
                'summerBankHoliday',
                ['en' => 'Summer Bank Holiday'],
                new \DateTime("first monday of september {$this->year}", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
                $this->locale,
                Holiday::TYPE_BANK
            ));

            return;
        }

        $this->addHoliday(new Holiday(
            'summerBankHoliday',
            ['en' => 'Summer Bank Holiday'],
            new \DateTime("last monday of august {$this->year}", DateTimeZoneFactory::getDateTimeZone($this->timezone)),
            $this->locale,
            Holiday::TYPE_BANK
        ));
    }

    /**
     * Mothering Sunday is a day honouring mothers and mother churches, celebrated in the United Kingdom, Ireland on the
     * fourth Sunday in Lent since the Middle Ages. On Mothering Sunday, Christians have historically visited their
     * mother church—the church in which they received the sacrament of baptism.
     *
     * @see https://en.wikipedia.org/wiki/Mothering_Sunday
     *
     * @throws \Exception
     */
    protected function calculateMotheringSunday(): void
    {
        $date = $this->calculateEaster($this->year, $this->timezone);
        $date->sub(new \DateInterval('P3W'));

        $this->addHoliday(new Holiday(
            'motheringSunday',
            ['en' => 'Mothering Sunday'],
            $date,
            $this->locale,
            Holiday::TYPE_OTHER
        ));
    }
}
