Class DateIntervals - helper class to compute and format human readable date intervals , e.g. 1 hour 5 minutes 24 seconds

DateIntervals.php

<?php

/**
 * Helper class to compute human readable date intervals , e.g. 1 hour 5 minutes 24 seconds
 */
class DateIntervals
{
    private $forms = [
        'eng' => [
            'years' => ['year', 'years'],
            'months' => ['month', 'months'],
            'days' => ['day', 'days'],
            'hours' => ['hour', 'hours'],
            'minutes' => ['minute', 'minutes'],
            'seconds' => ['second', 'seconds'],
        ],
        'rus' => [
            'years' => ['год', 'года', 'лет'],
            'months' => ['месяц', 'месяца', 'месяцев'],
            'days' => ['день', 'дня', 'дней'],
            'hours' => ['час', 'часа', 'часов'],
            'minutes' => ['минута', 'минуты', 'минут'],
            'seconds' => ['секунда', 'секунды', 'секунд'],
        ],
    ];

    private $supported = ['eng' => true, 'rus' => true];

    /**
     * Get string interval
     *
     * @param string|\DateTime $date
     * @param string           $lang
     * @param int              $max       Max number of units (e.g., 2 units is 6 month 1 week) starting from largest
     * @param string           $separator 
     *
     * @return string
     *
     * @throws \Exception
     */
    public function getInterval($date, $lang = 'eng', $max = 3, $separator = ' ')
    {
        if (!$date instanceof \DateTime) {
            if (!is_string($date)) {
                throw new \Exception('Expected formatted string of \DateTime object.');
            }
            $timestamp = $this->getTimestamp($date);
            $date = new \DateTime();
            $date->setTimestamp($timestamp);
        }

        return $this->getIntervalString($date, $lang, $max, $separator);
    }

    /**
     * Plural forms of date strings
     *
     * @param $lang
     * @param int $number Number of days, weeks or etc
     * @param $wordForms
     *
     * @return string
     *
     * @throws \Exception
     */
    private function pluralRules($lang, $number, $wordForms)
    {
        switch ($lang) {
            case 'eng':
                return $number.' '.(($number === 1) ? $wordForms[0] : $wordForms[1]);
            case 'rus':
                $cases = array(2, 0, 1, 1, 1, 2);

                return $number.' '.$wordForms[($number % 100 > 4 && $number % 100 < 20) ? 2 : $cases[min($number % 10, 5)]];
            default:
                $supported = implode(', ', array_keys($this->supported));
                throw new \Exception("Wrong language argument passed. Supported languages are ({$supported})");
        }
    }

    /**
     * Get string representation of Datetime object
     *
     * @param \DateTime $date
     * @param string    $lang
     * @param int       $max       
     * @param string    $separator 
     *
     * @return string
     *
     * @throws \Exception
     */
    private function getIntervalString(\DateTime $date, $lang, $max, $separator)
    {
        $timeComponents = (array) $date->diff(new \DateTime());
        $notNullTimeComponents = array_values(array_filter(array_slice($timeComponents, 0, 6)));

        if (($max > 6) && ($max < 1) && !is_numeric($max)) {
            throw new \Exception('Max number of units should be a number between 1 and 6.');
        }
        $interval = [];
        for ($i = 0; $i < $max; ++$i) {
            // Если diff вернёт 0 лет мы должны исключить ненужные элементы из списка форм
            if (isset($notNullTimeComponents[$i])) {
                $formForNotNullComponent = array_values(array_slice($this->forms[$lang], -count($notNullTimeComponents)));
                $interval[] = $this->getFormattedTime($lang, $notNullTimeComponents[$i], $formForNotNullComponent[$i]);
            }
        }

        return implode($separator, $interval);
    }

    /**
     * Format date string
     *
     * @param string $lang
     * @param $number
     * @param $wordForms
     *
     * @return string
     */
    private function getFormattedTime($lang, $number, $wordForms)
    {
        return $this->pluralRules($lang, $number, $wordForms);
    }

    /**
     * @param $timestamp
     *
     * @return bool
     */
    private function isValidTimeStamp($timestamp)
    {
        if (ctype_digit($timestamp) && strtotime(date('Y-m-d H:i:s', $timestamp)) === (int) $timestamp) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * @param $dateString
     *
     * @return int
     *
     * @throws \Exception
     */
    private function getTimestamp($dateString)
    {
        if (!$this->isValidTimeStamp(strtotime($dateString))) {
            throw new \Exception('Not valid date string.');
        }

        return strtotime($dateString);
    }
}