Zhaqq\Xlsx\Support::convertDateTime()

Complexity

Conditions	17
Paths	252

Size

Total Lines	61
Code Lines	37

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

<?php
    public static function convertDateTime($dateInput)
    {
        $seconds = 0;    // Time expressed as fraction of 24h hours in seconds
        $year = $month = $day = 0;

        $date_time = $dateInput;
        if (preg_match("/(\d{4})\-(\d{2})\-(\d{2})/", $date_time, $matches)) {
            list($junk, $year, $month, $day) = $matches;
        }
        if (preg_match("/(\d+):(\d{2}):(\d{2})/", $date_time, $matches)) {
            list($junk, $hour, $min, $sec) = $matches;
            $seconds = ($hour * 60 * 60 + $min * 60 + $sec) / (24 * 60 * 60);
        }
        unset($junk);

        //using 1900 as epoch, not 1904, ignoring 1904 special case
        // Special cases for Excel.
        if ('1899-12-31' == "$year-$month-$day") {
            return $seconds;
        }    // Excel 1900 epoch
        if ('1900-01-00' == "$year-$month-$day") {
            return $seconds;
        }    // Excel 1900 epoch
        if ('1900-02-29' == "$year-$month-$day") {
            return 60 + $seconds;
        }    // Excel false leapday
        // We calculate the date by calculating the number of days since the epoch
        // and adjust for the number of leap days. We calculate the number of leap
        // days by normalising the year in relation to the epoch. Thus the year 2000
        // becomes 100 for 4 and 100 year leapdays and 400 for 400 year leapdays.
        $epoch = 1900;
        $offset = 0;
        $norm = 300;
        $range = $year - $epoch;
        // Set month days and check for leap year.
        $leap = ((0 == $year % 400) || ((0 == $year % 4) && ($year % 100))) ? 1 : 0;
        $mdays = [31, ($leap ? 29 : 28), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
        // Some boundary checks
        if ($year < $epoch || $year > 9999) {
            return 0;
        }
        if ($month < 1 || $month > 12) {
            return 0;
        }
        if ($day < 1 || $day > $mdays[$month - 1]) {
            return 0;
        }
        // Accumulate the number of days since the epoch.
        $days = $day;    // Add days for current month
        $days += array_sum(array_slice($mdays, 0, $month - 1));    // Add days for past months
        $days += $range * 365;                      // Add days for past years
        $days += intval(($range) / 4);             // Add leapdays
        $days -= intval(($range + $offset) / 100); // Subtract 100 year leapdays
        $days += intval(($range + $offset + $norm) / 400);  // Add 400 year leapdays
        $days -= $leap;                                      // Already counted above
        // Adjust for Excel erroneously treating 1900 as a leap year.
        if ($days > 59) {
            ++$days;
        }

        return $days + $seconds;
    }