gistfile1.php

<?php
function newBenefit($oldBenefit, $quality, $squares_eaten) {
  if($squares_eaten > 5) {
    return -1.1 * abs($oldBenefit);
  } else if($quality == 'cadbury') {
    return $oldBenefit * 0.8;
  } else {
    return $oldBenefit * 0.95;
  }
}

function eatChocolate($quality, $oldProductivity) {
  static $cumulativeBenefit = 1;
  static $squares_eaten = 0;
  static $qualityMap = array('cadbury' => 1.05, 'lindt' => 1.10, 'xocolatl' => 1.25);

  $cumulativeBenefit = newBenefit($cumulativeBenefit, $quality, $squares_eaten);
  $squares_eaten++;
  return $oldProductivity * (1 + ($qualityMap[$quality] * $cumulativeBenefit));
}
?>