Выдернул с Kohana, возможно поможет, Вам остается только переписать на Ruby, функция возвращает разницу между двумя числами
/**
* Returns time difference between two timestamps, in human readable format.
* If the second timestamp is not given, the current time will be used.
* Also consider using [Date::fuzzy_span] when displaying a span.
*
* $span = Date::span(60, 182, 'minutes,seconds'); // array('minutes' => 2, 'seconds' => 2)
* $span = Date::span(60, 182, 'minutes'); // 2
*
* @param integer $remote timestamp to find the span of
* @param integer $local timestamp to use as the baseline
* @param string $output formatting string
* @return string when only a single output is requested
* @return array associative list of all outputs requested
*/
public static function span($remote, $local = NULL, $output = 'years,months,weeks,days,hours,minutes,seconds')
{
// Normalize output
$output = trim(strtolower( (string) $output));
if ( ! $output)
{
// Invalid output
return FALSE;
}
// Array with the output formats
$output = preg_split('/[^a-z]+/', $output);
// Convert the list of outputs to an associative array
$output = array_combine($output, array_fill(0, count($output), 0));
// Make the output values into keys
extract(array_flip($output), EXTR_SKIP);
if ($local === NULL)
{
// Calculate the span from the current time
$local = time();
}
// Calculate timespan (seconds)
$timespan = abs($remote - $local);
if (isset($output['years']))
{
$timespan -= Date::YEAR * ($output['years'] = (int) floor($timespan / Date::YEAR));
}
if (isset($output['months']))
{
$timespan -= Date::MONTH * ($output['months'] = (int) floor($timespan / Date::MONTH));
}
if (isset($output['weeks']))
{
$timespan -= Date::WEEK * ($output['weeks'] = (int) floor($timespan / Date::WEEK));
}
if (isset($output['days']))
{
$timespan -= Date::DAY * ($output['days'] = (int) floor($timespan / Date::DAY));
}
if (isset($output['hours']))
{
$timespan -= Date::HOUR * ($output['hours'] = (int) floor($timespan / Date::HOUR));
}
if (isset($output['minutes']))
{
$timespan -= Date::MINUTE * ($output['minutes'] = (int) floor($timespan / Date::MINUTE));
}
// Seconds ago, 1
if (isset($output['seconds']))
{
$output['seconds'] = $timespan;
}
if (count($output) === 1)
{
// Only a single output was requested, return it
return array_pop($output);
}
// Return array
return $output;
}
