<?php

/**
 * Хелпер для работы с датой и временем
 */
abstract class Date
{
    const MYSQL_FORMAT = 'Y-m-d H:i:s';
    const MYSQL_FORMAT_DATE = 'Y-m-d';
    const DEADLINE_DONE = 'Сдан';

    private static $endingPeriodFomat = '%d квартал %d';

    public static function getQuarterByMonth($month)
    {
        assert('$month>0');
        assert('$month<13');

        return ceil(($month)/3);
    }

    /**
     * 2030-06-20 => 2 квартал 2030
     * @param string $ep ending period
     * @param Clock|null $clock
     * @return string
     */
    public static function getFormatedEndingPeriod($ep, Clock $clock = null)
    {
	if ($clock === null) {
	    $clock = new RealtimeClock();
	}
        $curQuarter = self::getQuarterByMonth($clock->now()->format('m'));
        $curYear = (int)$clock->now()->format('Y');

        $parts = explode('-', $ep);

        if (count($parts) != 3) {
            return '';
        }

        $quarter = self::getQuarterByMonth((int)$parts[1]);
        $year = (int)$parts[0];

        if (
            $year < $curYear || $year == $curYear
            && $quarter < $curQuarter
        ) {
            return self::DEADLINE_DONE;
        }

        return sprintf(self::$endingPeriodFomat, $quarter, $year);
    }

    public static function parseDateTime($str)
    {
        return (int)strtotime($str);
    }

    public static function dateToMysql($time)
    {
        return date(self::MYSQL_FORMAT_DATE, $time);
    }

    public static function dateTimeToMysql($time)
    {
        return date(self::MYSQL_FORMAT, $time);
    }

    public static function getLastPeriodDate($ts)
    {
        $parts = explode('-', date('Y-m-d', $ts));
        $i = floor($parts[1]/4)+1;
        $lastDay = ($i == 1 && $i ==2) ? 30 : 31;
        $month = 3*$i;

        return $parts[0] . "-" .  $month . "-". $lastDay;
    }

    public static function getDateForApi($date)
    {
        $ts = self::parseDateTime($date);
        return date('d.m.Y', $ts);
    }

    public static function getListDeadlines($count = 10)
    {
        $lastDay = [
            3 => 31, // март
            6 => 30, // июнь
            9 => 30, // сентябрь
            12 => 31, // декабрь
        ];
        // предыдущий квартал: сдан
        $quarter = self::getQuarterByMonth((int)date('m')) -1;
        $year = (int)date('Y');
        if (!$quarter) {
            $quarter = 4;
            --$year;
        }

        $list = [];
        while ($count--) {
            $month = $quarter*3;
            $ts = mktime(0, 0, 0, $month, $lastDay[$month], $year);
            $formated = self::dateToMysql($ts);
            $list[$ts] = self::getFormatedEndingPeriod($formated);
            if (++$quarter > 4) {
                $quarter = 1;
                ++$year;
            }
        }
        return $list;
    }
}