Creating ISO 8601 durations

duration.php

<?php

$parts = secondsToDuration(61);
assert($parts['hours'] === 0);
assert($parts['minutes'] === 1);
assert($parts['seconds'] === 1);
assert('PT0H1M1S' === formatDuration($parts));

$parts = secondsToDuration(7202);
assert($parts['hours'] === 2);
assert($parts['minutes'] === 0);
assert($parts['seconds'] === 2);
assert('PT2H0M2S' === formatDuration($parts));

$parts = secondsToDuration(0);
assert($parts['hours'] === 0);
assert($parts['minutes'] === 0);
assert($parts['seconds'] === 0);
assert('PT0H0M0S' === formatDuration($parts));


echo "all passed\n";

// ----

/**
 * Convert a number of seconds to whole numbers of hours, minutes, seconds
 * @param {int}
 * @return {hash}
 */
function secondsToDuration ($seconds) {
  $remaining = $seconds;
  $parts = array();
  $multipliers = array(
    'hours' => 3600,
    'minutes' => 60,
    'seconds' => 1
  );

  foreach ($multipliers as $type => $m) {
    $parts[$type] = (int)($remaining / $m);
    $remaining -= ($parts[$type] * $m);
  }

  return $parts;
}

/**
 * Format a duration as ISO 8601
 * @param {hash}
 * @return {string}
 */
function formatDuration ($parts) {
  $default = array(
    'hours' => 0, 
    'minutes' => 0,
    'seconds' => 0
  );

  extract(array_merge($default, $parts));
                   
  return "PT{$hours}H{$minutes}M{$seconds}S";
}