EE new dr formula

Changeset #15

/**
 * @param $cnum country number
 * @param $news combined att and def news of a country
 * @src http://earthempires.com/forum/announcements/20140201-changeset-15-restart-aid-abbr-diminishing-returns-29694?t=1393414830
 */
function getDR( $cnum, $newsObj ) {
  // For each hit within the past 72 hours, add 1/2^(T/H).
  // where:
  //  T = hours have passed since the hit
  //  H = halflife; 20 average oversend; 18 if DH

  $timeAgo = strtotime( "72 hours ago" );
  $now = time();
  $dr = 0;
  $_bounced = 18;

  // 10  Nuclear Missile
  // 11  Chemical Missile
  // 12  Cruise Missile
  $no_dr_attack_type = array('10', '11', '12');

  // 5  Guerilla Strike
  // 6  Bombing Run
  // 7  Artillery Barrage
  $special_attack_type = array('5', '6', '7');

  // iterate over the news;
  // stop when over $timeAgo;
  foreach ($newsObj as $key => $value) {
    
    // we need to put this one here
    // so each iteration, the half-life 
    // gets re-intialized to the default value
    $_hl = 20;

    if ($value['timestamp'] >= $timeAgo) {
      $_t = number_format(($now-$value['timestamp'])/3600, 2);

      if ($value['win']==='0') { // bounced
        $_hl = $_bounced;
      }

      $_exp = $_t/$_hl;

      $_mod = 1/pow(2, $_exp);

      if ($cnum === $value['defender_num'] && !in_array($value['type'], $no_dr_attack_type)) {
        // defends

        // ignore failed special attacks
        if ($value['win']==='0' && in_array($value['type'], $special_attack_type)) {
          continue;
        } else {
          $dr = $dr + $_mod;
        }
      } else {
        // attacks
        if ($dr>0) {
          $tmp = $dr - $_mod;
          if ($tmp>0) {
            $dr = $tmp;
          } else {
            $dr = 0;
          }
        }
      }
    } else {
      break;
    }
  }

  return number_format($dr,2);
}

Ignored failed special incoming attacks: gs, br, ab