Implemented buchholz

src/Tiebreaks.php

@@ -160,4 +160,32 @@ abstract class Tiebreaks extends Tournament
         }
         return $tiebreak;
     }
+
+
+    /**
+     * @param Player $player
+     * @param int $cutlowest
+     * @param int $cuthighest
+     * @return int
+     */
+    protected function calculateBuchholz(Player $player, int $cutlowest = 0, int $cuthighest = 0)
+    {
+        $tiebreak = 0;
+        $intpairings = $player->getPairings();
+
+        usort($intpairings, function ($a, $b) {
+            if ($b->getOpponent()->getElo('home') == $a->getOpponent()->getElo('home')) {
+                return 0;
+            }
+            return ($b->getOpponent()->getElo('home') > $a->getOpponent()->getElo('home')) ? 1 : -1;
+        });
+
+        array_splice($intpairings, $cutlowest);
+        array_splice($intpairings, 0 - $cuthighest);
+
+        foreach ($intpairings as $intkey=>$intpairing) {
+            $tiebreak += $intpairing->getOpponent()->getPoints();
+        }
+        return $tiebreak;
+    }
 }

src/Tournament.php

@@ -299,6 +299,15 @@ class Tournament extends Tiebreaks
             case Tiebreak::Koya:
                 return $this->calculateKoya($player);
                 break;
+            case Tiebreak::Buchholz:
+                return $this->calculateBuchholz($player);
+                break;
+            case Tiebreak::BuchholzCut:
+                return $this->calculateBuchholz($player, 1);
+                break;
+            case Tiebreak::BuchholzMed:
+                return $this->calculateBuchholz($player, 1, 1);
+                break;
             default:
                 return null;
         }