A DateInterval extension class

DateIntervalEnhanced.class.php

<?php

/**
 * This class brings support for milliseconds, explicit recalculation of carry-over points
 * and human-friendly formatting
 */
class DateIntervalEnhanced extends DateInterval
{
    public $ms = 0;
    private $unitData = array(
        'y' => [
            'fullUnit' => 'year(s)'
        ],
        'm' => [
            'fullUnit' => 'month(s)'
        ],
        'd' => [
            'fullUnit' => 'day(s)'
        ],
        'h' => [
            'fullUnit' => 'hour(s)',
            'max' => 24,
            'parent' => 'd'
        ],
        'i' => [
            'shortUnit' => 'm',
            'fullUnit' => 'minute(s)',
            'max' => 60,
            'parent' => 'h'
        ],
        's' => [
            'fullUnit' => 'second(s)',
            'max' => 60,
            'parent' => 'i'
        ],
        'ms' => [
            'max' => 1000,
            'parent' => 's'
        ]
    );

    public function __construct($interval_spec) {
        if (preg_match('/\.(\d+)S$/', $interval_spec, $matches)) {
            $this->ms = (int) str_pad($matches[1], 3, '0');

            $interval_spec = str_replace($matches[0], 'S', $interval_spec);
        }

        parent::__construct($interval_spec);
    }

    /**
     * Recalculates carry-over points for time data (only)
     */
    public function recalculateTime() {
        $vars = array_slice($this->unitData, 3);

        foreach (array_reverse($vars) as $unit => $unitData) {
            if ($this->$unit >= $unitData['max']) {
                $this->{$unitData['parent']} += floor($this->$unit / $unitData['max']);
                $this->$unit %= $unitData['max'];
            }
        }
    }

    /**
     * Recalculates all carry-over points relative to a given date
     *
     * @param \DateTime|string $date
     */
    public function recalculateForDate($date) {
        if (is_string($date)) {
            $date = new DateTimeImmutable($date);
        }

        $dateAfter = $date->add($this);
        $date = $date->diff($dateAfter);

        $standardUnits = array_slice(array_keys($this->unitData), 0, -1);

        foreach ($standardUnits as $unit) {
            $this->$unit = $date->$unit;
        }
    }

    /**
     * This method formats the data in a human-friendly way
     *
     * @param int  $maxUnits   specifies the maximum units it should output, -1 for unlimited
     * @param bool $fullUnits  whether to display full unit names or abbreviations
     * @return string
     */
    public function humanFormat($maxUnits = 2, $fullUnits = true) {
        $units = array();

        foreach ($this->unitData as $unit => $unitData) {
            if ($this->$unit > 0) {
                $fullUnitName = isset($unitData['fullUnit']) ? $unitData['fullUnit'] : $unit;
                $shortUnitName = isset($unitData['shortUnit']) ? $unitData['shortUnit'] : $unit;

                if ($fullUnits) {
                    if ($this->$unit > 1) {
                        $unitName = preg_replace('/\((\w+)\)$/', '$1', $fullUnitName);
                    } else {
                        $unitName = preg_replace('/\(\w+\)$/', '', $fullUnitName);
                    }
                } else {
                    $unitName = $shortUnitName;
                }

                $units[] = array(
                    $this->$unit,
                    $unitName
                );
            }

            if ($maxUnits != -1 && count($units) >= $maxUnits) {
                break;
            }
        }

        $unitNameSeparator = ($fullUnits) ? ' ' : '';
        $str = '';

        foreach ($units as $i => $unit) {
            if ($fullUnits) {
                if ($i == count($units) - 1 && $i > 0) {
                    $str .= ' and ';
                } elseif ($i > 0) {
                    $str .= ', ';
                }
            } else {
                $str .= ' ';
            }

            $str .= implode($unitNameSeparator, $unit);
        }

        return trim($str);
    }
}