PHP 计算复活节

Posted 2021-05-14

<?php
    /*
    PHP Easter Calculation Library

    Copyright (c) 2008, reusablecode.blogspot.com; some rights reserved.

    This work is licensed under the Creative Commons Attribution License. To view
    a copy of this license, visit http://creativecommons.org/licenses/by/3.0/ or
    send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California
    94305, USA.

    This function library allows calculation of the following ecclesiastical holidays:
    Ash Wednesday, Palm Sunday, Good Friday, Easter, Ascension Day, and Pentecost.

    Refer to Wikipedia for information on the purpose of these holidays..
    */

    // Determine the date of Easter for a given year.
    function dateEaster($someYear)
    {
        $goldenNumber = fmod($someYear, 19) + 1;

        if ($someYear <= 1752)
        {
            // Julian calendar
            $dominicalNumber = fmod($someYear + ($someYear / 4) + 5, 7);
            $paschalFullMoon = fmod(3 - (11 * $goldenNumber) - 7, 30);
        }
        else
        {
            // Gregorian calendar
            $dominicalNumber = fmod($someYear + ($someYear / 4) - ($someYear / 100) + ($someYear / 400), 7);
            $solarCorrection = ($someYear - 1600) / 100 - ($someYear - 1600) / 400;
            $lunarCorrection = ((($someYear - 1400) / 100) * 8) / 25;
            $paschalFullMoon = fmod(3 - 11 * $goldenNumber + $solarCorrection - $lunarCorrection, 30);
        }

        while ($dominicalNumber < 0)
        {
            $dominicalNumber += 7;
        }

        while ($paschalFullMoon < 0)
        {
            $paschalFullMoon += 30;
        }

        if ($paschalFullMoon == 29 || ($paschalFullMoon == 28 && $goldenNumber > 11))
        {
            $paschalFullMoon--;
        }

        $difference = fmod(4 - $paschalFullMoon - $dominicalNumber, 7);

        if ($difference < 0)
        {
            $difference += 7;
        }

        $dayEaster = $paschalFullMoon + $difference + 1;
        
        if ($dayEaster < 11)
        {
            // Easter occurs in March.            
            $dateEaster = mktime(0, 0, 0, 3, $dayEaster + 21, $someYear);
        }
        else
        {
            // Easter occurs in April.
            $dateEaster = mktime(0, 0, 0, 4, $dayEaster - 10, $someYear);
        }
        
        return $dateEaster;
    }

    // Determine the date of Good Friday for a given year.
    // Requires dateEaster()
    function dateGoodFriday($someYear)
    {
        $easter = getDate(dateEaster($someYear));
        return mktime(0, 0, 0, $easter[mon], $easter[mday] - 2, $easter[year]);
    }

    // Determine the date of Palm Sunday for a given year.
    // Requires dateEaster()
    function datePalmSunday($someYear)
    {
        $easter = getDate(dateEaster($someYear));
        return mktime(0, 0, 0, $easter[mon], $easter[mday] - 7, $easter[year]);
    }

    // Determines the date of Ash Wednesday for a given year.
    // Requires dateEaster()
    function dateAshWednesday($someYear)
    {
        $easter = getDate(dateEaster($someYear));
        return mktime(0, 0, 0, $easter[mon], $easter[mday] - 46, $easter[year]);
    }
    
    // Deteremines the date of Ascension Day for a given year.
    // Requires dateEaster()
    function dateAscensionDay($someYear)
    {
        $easter = getDate(dateEaster($someYear));
        return mktime(0, 0, 0, $easter[mon], $easter[mday] + 39, $easter[year]);
    }

    // Determines the date of Pentecost for a given year.
    // Requires dateEaster()
    function datePentecost($someYear)
    {
        $easter = getDate(dateEaster($someYear));
        return mktime(0, 0, 0, $easter[mon], $easter[mday] + 49, $easter[year]);
    }
    
    // Unit tests
    // $testYear = 2008;
    // echo "Ash Wednesday: " . date("j F Y", dateAshWednesday($testYear)) . "<br>";
    // echo "Palm Sunday: " . date("j F Y", datePalmSunday($testYear)) . "<br>";
    // echo "Good Friday: " . date("j F Y", dateGoodFriday($testYear)) . "<br>";
    // echo "Easter: " . date("j F Y", dateEaster($testYear)) . "<br>";
    // echo "Ascension Day: " . date("j F Y", dateAscensionDay($testYear)) . "<br>";
    // echo "Pentecost: " . date("j F Y", datePentecost($testYear)) . "<br>";
?>