Pull Request: to handle Excel calendar dates ('Y-m-d') and Excel pure time (values (H:i)

[schoolshark]

Thank, you! Very nice work! I had to change Date.php and Value.php
to ensure proper conversion of Dates and Times.
Please include it in further releases.

Thank U
Stefan

// value.php
/**
* Transform numeric values, distinguishing between Excel calendar dates and pure time values.
*
* - If the value is associated with a date format (Styles::FORMAT_DATE), it is passed as a float
* to the Date transformer to handle both calendar dates and time values correctly.
* - Otherwise, the value is checked if it contains a decimal point to determine if it should be
* cast as a float (e.g., fractional day representing time) or an integer (e.g., whole numbers).
*/
private function transformNumber(string $style, mixed $value): DateTimeImmutable|float|int
{
return match (true) {
$style && Styles::FORMAT_DATE === $this->styles->get(index: (int) $style) => $this->dateTransformer->transform(value: (float) $value),
default => preg_match(pattern: '/^\d+.\d+$/', subject: $value) ? (float) $value : (int) $value,
};
}

//Date.php
/**
* Transforms an Excel numeric value into a DateTimeImmutable object.
*
* - If the value is less than 1, it represents a pure time (e.g., 0.333333 for 08:00 a.m.).
* The value is converted into seconds since midnight and then transformed into an object
* containing only the time component.
* - If the value is 1 or greater, it represents a calendar date (optionally with time).
* The value is converted into a UNIX timestamp using the Excel epoch (1900-01-01) and
* transformed into a full DateTimeImmutable object.
*/
public function transform(float|int $value): DateTimeImmutable
{
// Handle pure time values (value < 1)
if ($value < 1) {
$totalSeconds = (int) round($value * 86400); // Convert fractional day to total seconds
$hours = floor($totalSeconds / 3600);
$minutes = floor(($totalSeconds % 3600) / 60);
// Create a DateTimeImmutable with only the time component
return new DateTimeImmutable(sprintf('%02d:%02d:00', $hours, $minutes));
}

    // Default/Standard: Handle full date or date-time values (value >= 1)
    $unix = (int) (($value - 25569) * 86400); // Convert Excel date to UNIX timestamp
    $date = gmdate(self::DATETIME_FORMAT, $unix);
    return date_create_immutable_from_format('!' . self::DATETIME_FORMAT, $date);
}